tests: move bfd tests to src/vnet/bfd/test

- Refactor make test code to be co-located with
  the vpp feature source code.

Type: test

Signed-off-by: Dave Wallace <dwallacelf@gmail.com>
Change-Id: I3ef69bc915d2217357a9e2b1afa1cfd6c363faa0

2 files changed, 3201 insertions, 0 deletions

diff --git a/src/vnet/bfd/test/bfd.py b/src/vnet/bfd/test/bfd.py
new file mode 100644
index 00000000000..9d44425ec9f
--- /dev/null
+++ b/src/vnet/bfd/test/bfd.py
@@ -0,0 +1,423 @@
+""" BFD protocol implementation """
+
+from random import randint
+from socket import AF_INET, AF_INET6, inet_pton
+from scapy.all import bind_layers
+from scapy.layers.inet import UDP
+from scapy.packet import Packet
+from scapy.fields import BitField, BitEnumField, XByteField, FlagsField,\
+    ConditionalField, StrField
+from vpp_object import VppObject
+from util import NumericConstant
+from vpp_papi import VppEnum
+
+
+class BFDDiagCode(NumericConstant):
+    """ BFD Diagnostic Code """
+    no_diagnostic = 0
+    control_detection_time_expired = 1
+    echo_function_failed = 2
+    neighbor_signaled_session_down = 3
+    forwarding_plane_reset = 4
+    path_down = 5
+    concatenated_path_down = 6
+    administratively_down = 7
+    reverse_concatenated_path_down = 8
+
+    desc_dict = {
+        no_diagnostic: "No diagnostic",
+        control_detection_time_expired: "Control Detection Time Expired",
+        echo_function_failed: "Echo Function Failed",
+        neighbor_signaled_session_down: "Neighbor Signaled Session Down",
+        forwarding_plane_reset: "Forwarding Plane Reset",
+        path_down: "Path Down",
+        concatenated_path_down: "Concatenated Path Down",
+        administratively_down: "Administratively Down",
+        reverse_concatenated_path_down: "Reverse Concatenated Path Down",
+    }
+
+
+class BFDState(NumericConstant):
+    """ BFD State """
+    admin_down = 0
+    down = 1
+    init = 2
+    up = 3
+
+    desc_dict = {
+        admin_down: "AdminDown",
+        down: "Down",
+        init: "Init",
+        up: "Up",
+    }
+
+
+class BFDAuthType(NumericConstant):
+    """ BFD Authentication Type """
+    no_auth = 0
+    simple_pwd = 1
+    keyed_md5 = 2
+    meticulous_keyed_md5 = 3
+    keyed_sha1 = 4
+    meticulous_keyed_sha1 = 5
+
+    desc_dict = {
+        no_auth: "No authentication",
+        simple_pwd: "Simple Password",
+        keyed_md5: "Keyed MD5",
+        meticulous_keyed_md5: "Meticulous Keyed MD5",
+        keyed_sha1: "Keyed SHA1",
+        meticulous_keyed_sha1: "Meticulous Keyed SHA1",
+    }
+
+
+def bfd_is_auth_used(pkt):
+    """ is packet authenticated? """
+    return "A" in pkt.sprintf("%BFD.flags%")
+
+
+def bfd_is_simple_pwd_used(pkt):
+    """ is simple password authentication used? """
+    return bfd_is_auth_used(pkt) and pkt.auth_type == BFDAuthType.simple_pwd
+
+
+def bfd_is_sha1_used(pkt):
+    """ is sha1 authentication used? """
+    return bfd_is_auth_used(pkt) and pkt.auth_type in \
+        (BFDAuthType.keyed_sha1, BFDAuthType.meticulous_keyed_sha1)
+
+
+def bfd_is_md5_used(pkt):
+    """ is md5 authentication used? """
+    return bfd_is_auth_used(pkt) and pkt.auth_type in \
+        (BFDAuthType.keyed_md5, BFDAuthType.meticulous_keyed_md5)
+
+
+def bfd_is_md5_or_sha1_used(pkt):
+    """ is md5 or sha1 used? """
+    return bfd_is_md5_used(pkt) or bfd_is_sha1_used(pkt)
+
+
+class BFD(Packet):
+    """ BFD protocol layer for scapy """
+
+    udp_dport = 3784  #: BFD destination port per RFC 5881
+    udp_dport_echo = 3785  # : BFD destination port for ECHO per RFC 5881
+    udp_sport_min = 49152  #: BFD source port min value per RFC 5881
+    udp_sport_max = 65535  #: BFD source port max value per RFC 5881
+    bfd_pkt_len = 24  # : length of BFD pkt without authentication section
+    sha1_auth_len = 28  # : length of authentication section if SHA1 used
+
+    name = "BFD"
+
+    fields_desc = [
+        BitField("version", 1, 3),
+        BitEnumField("diag", 0, 5, BFDDiagCode.desc_dict),
+        BitEnumField("state", 0, 2, BFDState.desc_dict),
+        FlagsField("flags", 0, 6, ['M', 'D', 'A', 'C', 'F', 'P']),
+        XByteField("detect_mult", 0),
+        BitField("length", bfd_pkt_len, 8),
+        BitField("my_discriminator", 0, 32),
+        BitField("your_discriminator", 0, 32),
+        BitField("desired_min_tx_interval", 0, 32),
+        BitField("required_min_rx_interval", 0, 32),
+        BitField("required_min_echo_rx_interval", 0, 32),
+        ConditionalField(
+            BitEnumField("auth_type", 0, 8, BFDAuthType.desc_dict),
+            bfd_is_auth_used),
+        ConditionalField(BitField("auth_len", 0, 8), bfd_is_auth_used),
+        ConditionalField(BitField("auth_key_id", 0, 8), bfd_is_auth_used),
+        ConditionalField(BitField("auth_reserved", 0, 8),
+                         bfd_is_md5_or_sha1_used),
+        ConditionalField(
+            BitField("auth_seq_num", 0, 32), bfd_is_md5_or_sha1_used),
+        ConditionalField(StrField("auth_key_hash", "0" * 16), bfd_is_md5_used),
+        ConditionalField(
+            StrField("auth_key_hash", "0" * 20), bfd_is_sha1_used),
+    ]
+
+    def mysummary(self):
+        return self.sprintf("BFD(my_disc=%BFD.my_discriminator%,"
+                            "your_disc=%BFD.your_discriminator%)")
+
+
+# glue the BFD packet class to scapy parser
+bind_layers(UDP, BFD, dport=BFD.udp_dport)
+
+
+class BFD_vpp_echo(Packet):
+    """ BFD echo packet as used by VPP (non-rfc, as rfc doesn't define one) """
+
+    udp_dport = 3785  #: BFD echo destination port per RFC 5881
+    name = "BFD_VPP_ECHO"
+
+    fields_desc = [
+        BitField("discriminator", 0, 32),
+        BitField("expire_time_clocks", 0, 64),
+        BitField("checksum", 0, 64)
+    ]
+
+    def mysummary(self):
+        return self.sprintf(
+            "BFD_VPP_ECHO(disc=%BFD_VPP_ECHO.discriminator%,"
+            "expire_time_clocks=%BFD_VPP_ECHO.expire_time_clocks%)")
+
+
+# glue the BFD echo packet class to scapy parser
+bind_layers(UDP, BFD_vpp_echo, dport=BFD_vpp_echo.udp_dport)
+
+
+class VppBFDAuthKey(VppObject):
+    """ Represents BFD authentication key in VPP """
+
+    def __init__(self, test, conf_key_id, auth_type, key):
+        self._test = test
+        self._key = key
+        self._auth_type = auth_type
+        test.assertIn(auth_type, BFDAuthType.desc_dict)
+        self._conf_key_id = conf_key_id
+
+    @property
+    def test(self):
+        """ Test which created this key """
+        return self._test
+
+    @property
+    def auth_type(self):
+        """ Authentication type for this key """
+        return self._auth_type
+
+    @property
+    def key(self):
+        """ key data """
+        return self._key
+
+    @key.setter
+    def key(self, value):
+        self._key = value
+
+    @property
+    def conf_key_id(self):
+        """ configuration key ID """
+        return self._conf_key_id
+
+    def add_vpp_config(self):
+        self.test.vapi.bfd_auth_set_key(
+            conf_key_id=self._conf_key_id, auth_type=self._auth_type,
+            key=self._key, key_len=len(self._key))
+        self._test.registry.register(self, self.test.logger)
+
+    def get_bfd_auth_keys_dump_entry(self):
+        """ get the entry in the auth keys dump corresponding to this key """
+        result = self.test.vapi.bfd_auth_keys_dump()
+        for k in result:
+            if k.conf_key_id == self._conf_key_id:
+                return k
+        return None
+
+    def query_vpp_config(self):
+        return self.get_bfd_auth_keys_dump_entry() is not None
+
+    def remove_vpp_config(self):
+        self.test.vapi.bfd_auth_del_key(conf_key_id=self._conf_key_id)
+
+    def object_id(self):
+        return "bfd-auth-key-%s" % self._conf_key_id
+
+
+class VppBFDUDPSession(VppObject):
+    """ Represents BFD UDP session in VPP """
+
+    def __init__(self, test, interface, peer_addr, local_addr=None, af=AF_INET,
+                 desired_min_tx=300000, required_min_rx=300000, detect_mult=3,
+                 sha1_key=None, bfd_key_id=None, is_tunnel=False):
+        self._test = test
+        self._interface = interface
+        self._af = af
+        if local_addr:
+            self._local_addr = local_addr
+        else:
+            self._local_addr = None
+        self._peer_addr = peer_addr
+        self._desired_min_tx = desired_min_tx
+        self._required_min_rx = required_min_rx
+        self._detect_mult = detect_mult
+        self._sha1_key = sha1_key
+        if bfd_key_id is not None:
+            self._bfd_key_id = bfd_key_id
+        else:
+            self._bfd_key_id = randint(0, 255)
+        self._is_tunnel = is_tunnel
+
+    @property
+    def test(self):
+        """ Test which created this session """
+        return self._test
+
+    @property
+    def interface(self):
+        """ Interface on which this session lives """
+        return self._interface
+
+    @property
+    def af(self):
+        """ Address family - AF_INET or AF_INET6 """
+        return self._af
+
+    @property
+    def local_addr(self):
+        """ BFD session local address (VPP address) """
+        if self._local_addr is None:
+            if self.af == AF_INET:
+                return self._interface.local_ip4
+            elif self.af == AF_INET6:
+                return self._interface.local_ip6
+            else:
+                raise Exception("Unexpected af '%s'" % self.af)
+        return self._local_addr
+
+    @property
+    def peer_addr(self):
+        """ BFD session peer address """
+        return self._peer_addr
+
+    def get_bfd_udp_session_dump_entry(self):
+        """ get the namedtuple entry from bfd udp session dump """
+        result = self.test.vapi.bfd_udp_session_dump()
+        for s in result:
+            self.test.logger.debug("session entry: %s" % str(s))
+            if s.sw_if_index == self.interface.sw_if_index:
+                if self.af == AF_INET \
+                        and self.interface.local_ip4 == str(s.local_addr) \
+                        and self.interface.remote_ip4 == str(s.peer_addr):
+                    return s
+                if self.af == AF_INET6 \
+                        and self.interface.local_ip6 == str(s.local_addr) \
+                        and self.interface.remote_ip6 == str(s.peer_addr):
+                    return s
+        return None
+
+    @property
+    def state(self):
+        """ BFD session state """
+        session = self.get_bfd_udp_session_dump_entry()
+        if session is None:
+            raise Exception("Could not find BFD session in VPP response")
+        return session.state
+
+    @property
+    def desired_min_tx(self):
+        """ desired minimum tx interval """
+        return self._desired_min_tx
+
+    @property
+    def required_min_rx(self):
+        """ required minimum rx interval """
+        return self._required_min_rx
+
+    @property
+    def detect_mult(self):
+        """ detect multiplier """
+        return self._detect_mult
+
+    @property
+    def sha1_key(self):
+        """ sha1 key """
+        return self._sha1_key
+
+    @property
+    def bfd_key_id(self):
+        """ bfd key id in use """
+        return self._bfd_key_id
+
+    @property
+    def is_tunnel(self):
+        return self._is_tunnel
+
+    def activate_auth(self, key, bfd_key_id=None, delayed=False):
+        """ activate authentication for this session """
+        self._bfd_key_id = bfd_key_id if bfd_key_id else randint(0, 255)
+        self._sha1_key = key
+        conf_key_id = self._sha1_key.conf_key_id
+        is_delayed = 1 if delayed else 0
+        self.test.vapi.bfd_udp_auth_activate(
+            sw_if_index=self._interface.sw_if_index,
+            local_addr=self.local_addr,
+            peer_addr=self.peer_addr,
+            bfd_key_id=self._bfd_key_id,
+            conf_key_id=conf_key_id,
+            is_delayed=is_delayed)
+
+    def deactivate_auth(self, delayed=False):
+        """ deactivate authentication """
+        self._bfd_key_id = None
+        self._sha1_key = None
+        is_delayed = 1 if delayed else 0
+        self.test.vapi.bfd_udp_auth_deactivate(
+            sw_if_index=self._interface.sw_if_index,
+            local_addr=self.local_addr,
+            peer_addr=self.peer_addr,
+            is_delayed=is_delayed)
+
+    def modify_parameters(self,
+                          detect_mult=None,
+                          desired_min_tx=None,
+                          required_min_rx=None):
+        """ modify session parameters """
+        if detect_mult:
+            self._detect_mult = detect_mult
+        if desired_min_tx:
+            self._desired_min_tx = desired_min_tx
+        if required_min_rx:
+            self._required_min_rx = required_min_rx
+        self.test.vapi.bfd_udp_mod(sw_if_index=self._interface.sw_if_index,
+                                   desired_min_tx=self.desired_min_tx,
+                                   required_min_rx=self.required_min_rx,
+                                   detect_mult=self.detect_mult,
+                                   local_addr=self.local_addr,
+                                   peer_addr=self.peer_addr)
+
+    def add_vpp_config(self):
+        bfd_key_id = self._bfd_key_id if self._sha1_key else None
+        conf_key_id = self._sha1_key.conf_key_id if self._sha1_key else None
+        is_authenticated = True if self._sha1_key else False
+        self.test.vapi.bfd_udp_add(sw_if_index=self._interface.sw_if_index,
+                                   desired_min_tx=self.desired_min_tx,
+                                   required_min_rx=self.required_min_rx,
+                                   detect_mult=self.detect_mult,
+                                   local_addr=self.local_addr,
+                                   peer_addr=self.peer_addr,
+                                   bfd_key_id=bfd_key_id,
+                                   conf_key_id=conf_key_id,
+                                   is_authenticated=is_authenticated)
+        self._test.registry.register(self, self.test.logger)
+
+    def query_vpp_config(self):
+        session = self.get_bfd_udp_session_dump_entry()
+        return session is not None
+
+    def remove_vpp_config(self):
+        self.test.vapi.bfd_udp_del(self._interface.sw_if_index,
+                                   local_addr=self.local_addr,
+                                   peer_addr=self.peer_addr)
+
+    def object_id(self):
+        return "bfd-udp-%s-%s-%s-%s" % (self._interface.sw_if_index,
+                                        self.local_addr,
+                                        self.peer_addr,
+                                        self.af)
+
+    def admin_up(self):
+        """ set bfd session admin-up """
+        self.test.vapi.bfd_udp_session_set_flags(
+            flags=VppEnum.vl_api_if_status_flags_t.IF_STATUS_API_FLAG_ADMIN_UP,
+            sw_if_index=self._interface.sw_if_index,
+            local_addr=self.local_addr,
+            peer_addr=self.peer_addr)
+
+    def admin_down(self):
+        """ set bfd session admin-down """
+        self.test.vapi.bfd_udp_session_set_flags(
+            flags=0, sw_if_index=self._interface.sw_if_index,
+            local_addr=self.local_addr,
+            peer_addr=self.peer_addr)
diff --git a/src/vnet/bfd/test/test_bfd.py b/src/vnet/bfd/test/test_bfd.py
new file mode 100644
index 00000000000..784cdadb24d
--- /dev/null
+++ b/src/vnet/bfd/test/test_bfd.py
@@ -0,0 +1,2778 @@
+#!/usr/bin/env python3
+""" BFD tests """
+
+from __future__ import division
+
+import binascii
+import hashlib
+import ipaddress
+import reprlib
+import time
+import unittest
+from random import randint, shuffle, getrandbits
+from socket import AF_INET, AF_INET6, inet_ntop
+from struct import pack, unpack
+
+import scapy.compat
+from scapy.layers.inet import UDP, IP
+from scapy.layers.inet6 import IPv6
+from scapy.layers.l2 import Ether, GRE
+from scapy.packet import Raw
+
+from bfd import VppBFDAuthKey, BFD, BFDAuthType, VppBFDUDPSession, \
+    BFDDiagCode, BFDState, BFD_vpp_echo
+from framework import VppTestCase, VppTestRunner, running_extended_tests
+from util import ppp
+from vpp_ip import DpoProto
+from vpp_ip_route import VppIpRoute, VppRoutePath
+from vpp_lo_interface import VppLoInterface
+from vpp_papi_provider import UnexpectedApiReturnValueError, \
+    CliFailedCommandError
+from vpp_pg_interface import CaptureTimeoutError, is_ipv6_misc
+from vpp_gre_interface import VppGreInterface
+from vpp_papi import VppEnum
+
+USEC_IN_SEC = 1000000
+
+
+class AuthKeyFactory(object):
+    """Factory class for creating auth keys with unique conf key ID"""
+
+    def __init__(self):
+        self._conf_key_ids = {}
+
+    def create_random_key(self, test, auth_type=BFDAuthType.keyed_sha1):
+        """ create a random key with unique conf key id """
+        conf_key_id = randint(0, 0xFFFFFFFF)
+        while conf_key_id in self._conf_key_ids:
+            conf_key_id = randint(0, 0xFFFFFFFF)
+        self._conf_key_ids[conf_key_id] = 1
+        key = scapy.compat.raw(
+            bytearray([randint(0, 255) for _ in range(randint(1, 20))]))
+        return VppBFDAuthKey(test=test, auth_type=auth_type,
+                             conf_key_id=conf_key_id, key=key)
+
+
+class BFDAPITestCase(VppTestCase):
+    """Bidirectional Forwarding Detection (BFD) - API"""
+
+    pg0 = None
+    pg1 = None
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFDAPITestCase, cls).setUpClass()
+        cls.vapi.cli("set log class bfd level debug")
+        try:
+            cls.create_pg_interfaces(range(2))
+            for i in cls.pg_interfaces:
+                i.config_ip4()
+                i.config_ip6()
+                i.resolve_arp()
+
+        except Exception:
+            super(BFDAPITestCase, cls).tearDownClass()
+            raise
+
+    @classmethod
+    def tearDownClass(cls):
+        super(BFDAPITestCase, cls).tearDownClass()
+
+    def setUp(self):
+        super(BFDAPITestCase, self).setUp()
+        self.factory = AuthKeyFactory()
+
+    def test_add_bfd(self):
+        """ create a BFD session """
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        session.add_vpp_config()
+        self.logger.debug("Session state is %s", session.state)
+        session.remove_vpp_config()
+        session.add_vpp_config()
+        self.logger.debug("Session state is %s", session.state)
+        session.remove_vpp_config()
+
+    def test_double_add(self):
+        """ create the same BFD session twice (negative case) """
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        session.add_vpp_config()
+
+        with self.vapi.assert_negative_api_retval():
+            session.add_vpp_config()
+
+        session.remove_vpp_config()
+
+    def test_add_bfd6(self):
+        """ create IPv6 BFD session """
+        session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip6, af=AF_INET6)
+        session.add_vpp_config()
+        self.logger.debug("Session state is %s", session.state)
+        session.remove_vpp_config()
+        session.add_vpp_config()
+        self.logger.debug("Session state is %s", session.state)
+        session.remove_vpp_config()
+
+    def test_mod_bfd(self):
+        """ modify BFD session parameters """
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
+                                   desired_min_tx=50000,
+                                   required_min_rx=10000,
+                                   detect_mult=1)
+        session.add_vpp_config()
+        s = session.get_bfd_udp_session_dump_entry()
+        self.assert_equal(session.desired_min_tx,
+                          s.desired_min_tx,
+                          "desired min transmit interval")
+        self.assert_equal(session.required_min_rx,
+                          s.required_min_rx,
+                          "required min receive interval")
+        self.assert_equal(session.detect_mult, s.detect_mult, "detect mult")
+        session.modify_parameters(desired_min_tx=session.desired_min_tx * 2,
+                                  required_min_rx=session.required_min_rx * 2,
+                                  detect_mult=session.detect_mult * 2)
+        s = session.get_bfd_udp_session_dump_entry()
+        self.assert_equal(session.desired_min_tx,
+                          s.desired_min_tx,
+                          "desired min transmit interval")
+        self.assert_equal(session.required_min_rx,
+                          s.required_min_rx,
+                          "required min receive interval")
+        self.assert_equal(session.detect_mult, s.detect_mult, "detect mult")
+
+    def test_add_sha1_keys(self):
+        """ add SHA1 keys """
+        key_count = 10
+        keys = [self.factory.create_random_key(
+            self) for i in range(0, key_count)]
+        for key in keys:
+            self.assertFalse(key.query_vpp_config())
+        for key in keys:
+            key.add_vpp_config()
+        for key in keys:
+            self.assertTrue(key.query_vpp_config())
+        # remove randomly
+        indexes = list(range(key_count))
+        shuffle(indexes)
+        removed = []
+        for i in indexes:
+            key = keys[i]
+            key.remove_vpp_config()
+            removed.append(i)
+            for j in range(key_count):
+                key = keys[j]
+                if j in removed:
+                    self.assertFalse(key.query_vpp_config())
+                else:
+                    self.assertTrue(key.query_vpp_config())
+        # should be removed now
+        for key in keys:
+            self.assertFalse(key.query_vpp_config())
+        # add back and remove again
+        for key in keys:
+            key.add_vpp_config()
+        for key in keys:
+            self.assertTrue(key.query_vpp_config())
+        for key in keys:
+            key.remove_vpp_config()
+        for key in keys:
+            self.assertFalse(key.query_vpp_config())
+
+    def test_add_bfd_sha1(self):
+        """ create a BFD session (SHA1) """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
+                                   sha1_key=key)
+        session.add_vpp_config()
+        self.logger.debug("Session state is %s", session.state)
+        session.remove_vpp_config()
+        session.add_vpp_config()
+        self.logger.debug("Session state is %s", session.state)
+        session.remove_vpp_config()
+
+    def test_double_add_sha1(self):
+        """ create the same BFD session twice (negative case) (SHA1) """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
+                                   sha1_key=key)
+        session.add_vpp_config()
+        with self.assertRaises(Exception):
+            session.add_vpp_config()
+
+    def test_add_auth_nonexistent_key(self):
+        """ create BFD session using non-existent SHA1 (negative case) """
+        session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4,
+            sha1_key=self.factory.create_random_key(self))
+        with self.assertRaises(Exception):
+            session.add_vpp_config()
+
+    def test_shared_sha1_key(self):
+        """ share single SHA1 key between multiple BFD sessions """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        sessions = [
+            VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
+                             sha1_key=key),
+            VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip6,
+                             sha1_key=key, af=AF_INET6),
+            VppBFDUDPSession(self, self.pg1, self.pg1.remote_ip4,
+                             sha1_key=key),
+            VppBFDUDPSession(self, self.pg1, self.pg1.remote_ip6,
+                             sha1_key=key, af=AF_INET6)]
+        for s in sessions:
+            s.add_vpp_config()
+        removed = 0
+        for s in sessions:
+            e = key.get_bfd_auth_keys_dump_entry()
+            self.assert_equal(e.use_count, len(sessions) - removed,
+                              "Use count for shared key")
+            s.remove_vpp_config()
+            removed += 1
+        e = key.get_bfd_auth_keys_dump_entry()
+        self.assert_equal(e.use_count, len(sessions) - removed,
+                          "Use count for shared key")
+
+    def test_activate_auth(self):
+        """ activate SHA1 authentication """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        session.add_vpp_config()
+        session.activate_auth(key)
+
+    def test_deactivate_auth(self):
+        """ deactivate SHA1 authentication """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        session.add_vpp_config()
+        session.activate_auth(key)
+        session.deactivate_auth()
+
+    def test_change_key(self):
+        """ change SHA1 key """
+        key1 = self.factory.create_random_key(self)
+        key2 = self.factory.create_random_key(self)
+        while key2.conf_key_id == key1.conf_key_id:
+            key2 = self.factory.create_random_key(self)
+        key1.add_vpp_config()
+        key2.add_vpp_config()
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
+                                   sha1_key=key1)
+        session.add_vpp_config()
+        session.activate_auth(key2)
+
+    def test_set_del_udp_echo_source(self):
+        """ set/del udp echo source """
+        self.create_loopback_interfaces(1)
+        self.loopback0 = self.lo_interfaces[0]
+        self.loopback0.admin_up()
+        echo_source = self.vapi.bfd_udp_get_echo_source()
+        self.assertFalse(echo_source.is_set)
+        self.assertFalse(echo_source.have_usable_ip4)
+        self.assertFalse(echo_source.have_usable_ip6)
+
+        self.vapi.bfd_udp_set_echo_source(
+            sw_if_index=self.loopback0.sw_if_index)
+        echo_source = self.vapi.bfd_udp_get_echo_source()
+        self.assertTrue(echo_source.is_set)
+        self.assertEqual(echo_source.sw_if_index, self.loopback0.sw_if_index)
+        self.assertFalse(echo_source.have_usable_ip4)
+        self.assertFalse(echo_source.have_usable_ip6)
+
+        self.loopback0.config_ip4()
+        echo_ip4 = ipaddress.IPv4Address(int(ipaddress.IPv4Address(
+            self.loopback0.local_ip4)) ^ 1).packed
+        echo_source = self.vapi.bfd_udp_get_echo_source()
+        self.assertTrue(echo_source.is_set)
+        self.assertEqual(echo_source.sw_if_index, self.loopback0.sw_if_index)
+        self.assertTrue(echo_source.have_usable_ip4)
+        self.assertEqual(echo_source.ip4_addr.packed, echo_ip4)
+        self.assertFalse(echo_source.have_usable_ip6)
+
+        self.loopback0.config_ip6()
+        echo_ip6 = ipaddress.IPv6Address(int(ipaddress.IPv6Address(
+            self.loopback0.local_ip6)) ^ 1).packed
+
+        echo_source = self.vapi.bfd_udp_get_echo_source()
+        self.assertTrue(echo_source.is_set)
+        self.assertEqual(echo_source.sw_if_index, self.loopback0.sw_if_index)
+        self.assertTrue(echo_source.have_usable_ip4)
+        self.assertEqual(echo_source.ip4_addr.packed, echo_ip4)
+        self.assertTrue(echo_source.have_usable_ip6)
+        self.assertEqual(echo_source.ip6_addr.packed, echo_ip6)
+
+        self.vapi.bfd_udp_del_echo_source()
+        echo_source = self.vapi.bfd_udp_get_echo_source()
+        self.assertFalse(echo_source.is_set)
+        self.assertFalse(echo_source.have_usable_ip4)
+        self.assertFalse(echo_source.have_usable_ip6)
+
+
+class BFDTestSession(object):
+    """ BFD session as seen from test framework side """
+
+    def __init__(self, test, interface, af, detect_mult=3, sha1_key=None,
+                 bfd_key_id=None, our_seq_number=None,
+                 tunnel_header=None, phy_interface=None):
+        self.test = test
+        self.af = af
+        self.sha1_key = sha1_key
+        self.bfd_key_id = bfd_key_id
+        self.interface = interface
+        if phy_interface:
+            self.phy_interface = phy_interface
+        else:
+            self.phy_interface = self.interface
+        self.udp_sport = randint(49152, 65535)
+        if our_seq_number is None:
+            self.our_seq_number = randint(0, 40000000)
+        else:
+            self.our_seq_number = our_seq_number
+        self.vpp_seq_number = None
+        self.my_discriminator = 0
+        self.desired_min_tx = 300000
+        self.required_min_rx = 300000
+        self.required_min_echo_rx = None
+        self.detect_mult = detect_mult
+        self.diag = BFDDiagCode.no_diagnostic
+        self.your_discriminator = None
+        self.state = BFDState.down
+        self.auth_type = BFDAuthType.no_auth
+        self.tunnel_header = tunnel_header
+
+    def inc_seq_num(self):
+        """ increment sequence number, wrapping if needed """
+        if self.our_seq_number == 0xFFFFFFFF:
+            self.our_seq_number = 0
+        else:
+            self.our_seq_number += 1
+
+    def update(self, my_discriminator=None, your_discriminator=None,
+               desired_min_tx=None, required_min_rx=None,
+               required_min_echo_rx=None, detect_mult=None,
+               diag=None, state=None, auth_type=None):
+        """ update BFD parameters associated with session """
+        if my_discriminator is not None:
+            self.my_discriminator = my_discriminator
+        if your_discriminator is not None:
+            self.your_discriminator = your_discriminator
+        if required_min_rx is not None:
+            self.required_min_rx = required_min_rx
+        if required_min_echo_rx is not None:
+            self.required_min_echo_rx = required_min_echo_rx
+        if desired_min_tx is not None:
+            self.desired_min_tx = desired_min_tx
+        if detect_mult is not None:
+            self.detect_mult = detect_mult
+        if diag is not None:
+            self.diag = diag
+        if state is not None:
+            self.state = state
+        if auth_type is not None:
+            self.auth_type = auth_type
+
+    def fill_packet_fields(self, packet):
+        """ set packet fields with known values in packet """
+        bfd = packet[BFD]
+        if self.my_discriminator:
+            self.test.logger.debug("BFD: setting packet.my_discriminator=%s",
+                                   self.my_discriminator)
+            bfd.my_discriminator = self.my_discriminator
+        if self.your_discriminator:
+            self.test.logger.debug("BFD: setting packet.your_discriminator=%s",
+                                   self.your_discriminator)
+            bfd.your_discriminator = self.your_discriminator
+        if self.required_min_rx:
+            self.test.logger.debug(
+                "BFD: setting packet.required_min_rx_interval=%s",
+                self.required_min_rx)
+            bfd.required_min_rx_interval = self.required_min_rx
+        if self.required_min_echo_rx:
+            self.test.logger.debug(
+                "BFD: setting packet.required_min_echo_rx=%s",
+                self.required_min_echo_rx)
+            bfd.required_min_echo_rx_interval = self.required_min_echo_rx
+        if self.desired_min_tx:
+            self.test.logger.debug(
+                "BFD: setting packet.desired_min_tx_interval=%s",
+                self.desired_min_tx)
+            bfd.desired_min_tx_interval = self.desired_min_tx
+        if self.detect_mult:
+            self.test.logger.debug(
+                "BFD: setting packet.detect_mult=%s", self.detect_mult)
+            bfd.detect_mult = self.detect_mult
+        if self.diag:
+            self.test.logger.debug("BFD: setting packet.diag=%s", self.diag)
+            bfd.diag = self.diag
+        if self.state:
+            self.test.logger.debug("BFD: setting packet.state=%s", self.state)
+            bfd.state = self.state
+        if self.auth_type:
+            # this is used by a negative test-case
+            self.test.logger.debug("BFD: setting packet.auth_type=%s",
+                                   self.auth_type)
+            bfd.auth_type = self.auth_type
+
+    def create_packet(self):
+        """ create a BFD packet, reflecting the current state of session """
+        if self.sha1_key:
+            bfd = BFD(flags="A")
+            bfd.auth_type = self.sha1_key.auth_type
+            bfd.auth_len = BFD.sha1_auth_len
+            bfd.auth_key_id = self.bfd_key_id
+            bfd.auth_seq_num = self.our_seq_number
+            bfd.length = BFD.sha1_auth_len + BFD.bfd_pkt_len
+        else:
+            bfd = BFD()
+        packet = Ether(src=self.phy_interface.remote_mac,
+                       dst=self.phy_interface.local_mac)
+        if self.tunnel_header:
+            packet = packet / self.tunnel_header
+        if self.af == AF_INET6:
+            packet = (packet /
+                      IPv6(src=self.interface.remote_ip6,
+                           dst=self.interface.local_ip6,
+                           hlim=255) /
+                      UDP(sport=self.udp_sport, dport=BFD.udp_dport) /
+                      bfd)
+        else:
+            packet = (packet /
+                      IP(src=self.interface.remote_ip4,
+                         dst=self.interface.local_ip4,
+                         ttl=255) /
+                      UDP(sport=self.udp_sport, dport=BFD.udp_dport) /
+                      bfd)
+        self.test.logger.debug("BFD: Creating packet")
+        self.fill_packet_fields(packet)
+        if self.sha1_key:
+            hash_material = scapy.compat.raw(
+                packet[BFD])[:32] + self.sha1_key.key + \
+                b"\0" * (20 - len(self.sha1_key.key))
+            self.test.logger.debug("BFD: Calculated SHA1 hash: %s" %
+                                   hashlib.sha1(hash_material).hexdigest())
+            packet[BFD].auth_key_hash = hashlib.sha1(hash_material).digest()
+        return packet
+
+    def send_packet(self, packet=None, interface=None):
+        """ send packet on interface, creating the packet if needed """
+        if packet is None:
+            packet = self.create_packet()
+        if interface is None:
+            interface = self.phy_interface
+        self.test.logger.debug(ppp("Sending packet:", packet))
+        interface.add_stream(packet)
+        self.test.pg_start()
+
+    def verify_sha1_auth(self, packet):
+        """ Verify correctness of authentication in BFD layer. """
+        bfd = packet[BFD]
+        self.test.assert_equal(bfd.auth_len, 28, "Auth section length")
+        self.test.assert_equal(bfd.auth_type, self.sha1_key.auth_type,
+                               BFDAuthType)
+        self.test.assert_equal(bfd.auth_key_id, self.bfd_key_id, "Key ID")
+        self.test.assert_equal(bfd.auth_reserved, 0, "Reserved")
+        if self.vpp_seq_number is None:
+            self.vpp_seq_number = bfd.auth_seq_num
+            self.test.logger.debug("Received initial sequence number: %s" %
+                                   self.vpp_seq_number)
+        else:
+            recvd_seq_num = bfd.auth_seq_num
+            self.test.logger.debug("Received followup sequence number: %s" %
+                                   recvd_seq_num)
+            if self.vpp_seq_number < 0xffffffff:
+                if self.sha1_key.auth_type == \
+                        BFDAuthType.meticulous_keyed_sha1:
+                    self.test.assert_equal(recvd_seq_num,
+                                           self.vpp_seq_number + 1,
+                                           "BFD sequence number")
+                else:
+                    self.test.assert_in_range(recvd_seq_num,
+                                              self.vpp_seq_number,
+                                              self.vpp_seq_number + 1,
+                                              "BFD sequence number")
+            else:
+                if self.sha1_key.auth_type == \
+                        BFDAuthType.meticulous_keyed_sha1:
+                    self.test.assert_equal(recvd_seq_num, 0,
+                                           "BFD sequence number")
+                else:
+                    self.test.assertIn(recvd_seq_num, (self.vpp_seq_number, 0),
+                                       "BFD sequence number not one of "
+                                       "(%s, 0)" % self.vpp_seq_number)
+            self.vpp_seq_number = recvd_seq_num
+        # last 20 bytes represent the hash - so replace them with the key,
+        # pad the result with zeros and hash the result
+        hash_material = bfd.original[:-20] + self.sha1_key.key + \
+            b"\0" * (20 - len(self.sha1_key.key))
+        expected_hash = hashlib.sha1(hash_material).hexdigest()
+        self.test.assert_equal(binascii.hexlify(bfd.auth_key_hash),
+                               expected_hash.encode(), "Auth key hash")
+
+    def verify_bfd(self, packet):
+        """ Verify correctness of BFD layer. """
+        bfd = packet[BFD]
+        self.test.assert_equal(bfd.version, 1, "BFD version")
+        self.test.assert_equal(bfd.your_discriminator,
+                               self.my_discriminator,
+                               "BFD - your discriminator")
+        if self.sha1_key:
+            self.verify_sha1_auth(packet)
+
+
+def bfd_session_up(test):
+    """ Bring BFD session up """
+    test.logger.info("BFD: Waiting for slow hello")
+    p = wait_for_bfd_packet(test, 2, is_tunnel=test.vpp_session.is_tunnel)
+    old_offset = None
+    if hasattr(test, 'vpp_clock_offset'):
+        old_offset = test.vpp_clock_offset
+    test.vpp_clock_offset = time.time() - float(p.time)
+    test.logger.debug("BFD: Calculated vpp clock offset: %s",
+                      test.vpp_clock_offset)
+    if old_offset:
+        test.assertAlmostEqual(
+            old_offset, test.vpp_clock_offset, delta=0.5,
+            msg="vpp clock offset not stable (new: %s, old: %s)" %
+            (test.vpp_clock_offset, old_offset))
+    test.logger.info("BFD: Sending Init")
+    test.test_session.update(my_discriminator=randint(0, 40000000),
+                             your_discriminator=p[BFD].my_discriminator,
+                             state=BFDState.init)
+    if test.test_session.sha1_key and test.test_session.sha1_key.auth_type == \
+            BFDAuthType.meticulous_keyed_sha1:
+        test.test_session.inc_seq_num()
+    test.test_session.send_packet()
+    test.logger.info("BFD: Waiting for event")
+    e = test.vapi.wait_for_event(1, "bfd_udp_session_details")
+    verify_event(test, e, expected_state=BFDState.up)
+    test.logger.info("BFD: Session is Up")
+    test.test_session.update(state=BFDState.up)
+    if test.test_session.sha1_key and test.test_session.sha1_key.auth_type == \
+            BFDAuthType.meticulous_keyed_sha1:
+        test.test_session.inc_seq_num()
+    test.test_session.send_packet()
+    test.assert_equal(test.vpp_session.state, BFDState.up, BFDState)
+
+
+def bfd_session_down(test):
+    """ Bring BFD session down """
+    test.assert_equal(test.vpp_session.state, BFDState.up, BFDState)
+    test.test_session.update(state=BFDState.down)
+    if test.test_session.sha1_key and test.test_session.sha1_key.auth_type == \
+            BFDAuthType.meticulous_keyed_sha1:
+        test.test_session.inc_seq_num()
+    test.test_session.send_packet()
+    test.logger.info("BFD: Waiting for event")
+    e = test.vapi.wait_for_event(1, "bfd_udp_session_details")
+    verify_event(test, e, expected_state=BFDState.down)
+    test.logger.info("BFD: Session is Down")
+    test.assert_equal(test.vpp_session.state, BFDState.down, BFDState)
+
+
+def verify_bfd_session_config(test, session, state=None):
+    dump = session.get_bfd_udp_session_dump_entry()
+    test.assertIsNotNone(dump)
+    # since dump is not none, we have verified that sw_if_index and addresses
+    # are valid (in get_bfd_udp_session_dump_entry)
+    if state:
+        test.assert_equal(dump.state, state, "session state")
+    test.assert_equal(dump.required_min_rx, session.required_min_rx,
+                      "required min rx interval")
+    test.assert_equal(dump.desired_min_tx, session.desired_min_tx,
+                      "desired min tx interval")
+    test.assert_equal(dump.detect_mult, session.detect_mult,
+                      "detect multiplier")
+    if session.sha1_key is None:
+        test.assert_equal(dump.is_authenticated, 0, "is_authenticated flag")
+    else:
+        test.assert_equal(dump.is_authenticated, 1, "is_authenticated flag")
+        test.assert_equal(dump.bfd_key_id, session.bfd_key_id,
+                          "bfd key id")
+        test.assert_equal(dump.conf_key_id,
+                          session.sha1_key.conf_key_id,
+                          "config key id")
+
+
+def verify_ip(test, packet):
+    """ Verify correctness of IP layer. """
+    if test.vpp_session.af == AF_INET6:
+        ip = packet[IPv6]
+        local_ip = test.vpp_session.interface.local_ip6
+        remote_ip = test.vpp_session.interface.remote_ip6
+        test.assert_equal(ip.hlim, 255, "IPv6 hop limit")
+    else:
+        ip = packet[IP]
+        local_ip = test.vpp_session.interface.local_ip4
+        remote_ip = test.vpp_session.interface.remote_ip4
+        test.assert_equal(ip.ttl, 255, "IPv4 TTL")
+    test.assert_equal(ip.src, local_ip, "IP source address")
+    test.assert_equal(ip.dst, remote_ip, "IP destination address")
+
+
+def verify_udp(test, packet):
+    """ Verify correctness of UDP layer. """
+    udp = packet[UDP]
+    test.assert_equal(udp.dport, BFD.udp_dport, "UDP destination port")
+    test.assert_in_range(udp.sport, BFD.udp_sport_min, BFD.udp_sport_max,
+                         "UDP source port")
+
+
+def verify_event(test, event, expected_state):
+    """ Verify correctness of event values. """
+    e = event
+    test.logger.debug("BFD: Event: %s" % reprlib.repr(e))
+    test.assert_equal(e.sw_if_index,
+                      test.vpp_session.interface.sw_if_index,
+                      "BFD interface index")
+
+    test.assert_equal(str(e.local_addr), test.vpp_session.local_addr,
+                      "Local IPv6 address")
+    test.assert_equal(str(e.peer_addr), test.vpp_session.peer_addr,
+                      "Peer IPv6 address")
+    test.assert_equal(e.state, expected_state, BFDState)
+
+
+def wait_for_bfd_packet(test, timeout=1, pcap_time_min=None, is_tunnel=False):
+    """ wait for BFD packet and verify its correctness
+
+    :param timeout: how long to wait
+    :param pcap_time_min: ignore packets with pcap timestamp lower than this
+
+    :returns: tuple (packet, time spent waiting for packet)
+    """
+    test.logger.info("BFD: Waiting for BFD packet")
+    deadline = time.time() + timeout
+    counter = 0
+    while True:
+        counter += 1
+        # sanity check
+        test.assert_in_range(counter, 0, 100, "number of packets ignored")
+        time_left = deadline - time.time()
+        if time_left < 0:
+            raise CaptureTimeoutError("Packet did not arrive within timeout")
+        p = test.pg0.wait_for_packet(timeout=time_left)
+        test.logger.debug(ppp("BFD: Got packet:", p))
+        if pcap_time_min is not None and p.time < pcap_time_min:
+            test.logger.debug(ppp("BFD: ignoring packet (pcap time %s < "
+                                  "pcap time min %s):" %
+                                  (p.time, pcap_time_min), p))
+        else:
+            break
+    if is_tunnel:
+        # strip an IP layer and move to the next
+        p = p[IP].payload
+
+    bfd = p[BFD]
+    if bfd is None:
+        raise Exception(ppp("Unexpected or invalid BFD packet:", p))
+    if bfd.payload:
+        raise Exception(ppp("Unexpected payload in BFD packet:", bfd))
+    verify_ip(test, p)
+    verify_udp(test, p)
+    test.test_session.verify_bfd(p)
+    return p
+
+
+class BFD4TestCase(VppTestCase):
+    """Bidirectional Forwarding Detection (BFD)"""
+
+    pg0 = None
+    vpp_clock_offset = None
+    vpp_session = None
+    test_session = None
+
+    @classmethod
+    def force_solo(cls):
+        return True
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFD4TestCase, cls).setUpClass()
+        cls.vapi.cli("set log class bfd level debug")
+        try:
+            cls.create_pg_interfaces([0])
+            cls.create_loopback_interfaces(1)
+            cls.loopback0 = cls.lo_interfaces[0]
+            cls.loopback0.config_ip4()
+            cls.loopback0.admin_up()
+            cls.pg0.config_ip4()
+            cls.pg0.configure_ipv4_neighbors()
+            cls.pg0.admin_up()
+            cls.pg0.resolve_arp()
+
+        except Exception:
+            super(BFD4TestCase, cls).tearDownClass()
+            raise
+
+    @classmethod
+    def tearDownClass(cls):
+        super(BFD4TestCase, cls).tearDownClass()
+
+    def setUp(self):
+        super(BFD4TestCase, self).setUp()
+        self.factory = AuthKeyFactory()
+        self.vapi.want_bfd_events()
+        self.pg0.enable_capture()
+        try:
+            self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                                self.pg0.remote_ip4)
+            self.vpp_session.add_vpp_config()
+            self.vpp_session.admin_up()
+            self.test_session = BFDTestSession(self, self.pg0, AF_INET)
+        except BaseException:
+            self.vapi.want_bfd_events(enable_disable=0)
+            raise
+
+    def tearDown(self):
+        if not self.vpp_dead:
+            self.vapi.want_bfd_events(enable_disable=0)
+        self.vapi.collect_events()  # clear the event queue
+        super(BFD4TestCase, self).tearDown()
+
+    def test_session_up(self):
+        """ bring BFD session up """
+        bfd_session_up(self)
+
+    def test_session_up_by_ip(self):
+        """ bring BFD session up - first frame looked up by address pair """
+        self.logger.info("BFD: Sending Slow control frame")
+        self.test_session.update(my_discriminator=randint(0, 40000000))
+        self.test_session.send_packet()
+        self.pg0.enable_capture()
+        p = self.pg0.wait_for_packet(1)
+        self.assert_equal(p[BFD].your_discriminator,
+                          self.test_session.my_discriminator,
+                          "BFD - your discriminator")
+        self.assert_equal(p[BFD].state, BFDState.init, BFDState)
+        self.test_session.update(your_discriminator=p[BFD].my_discriminator,
+                                 state=BFDState.up)
+        self.logger.info("BFD: Waiting for event")
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        verify_event(self, e, expected_state=BFDState.init)
+        self.logger.info("BFD: Sending Up")
+        self.test_session.send_packet()
+        self.logger.info("BFD: Waiting for event")
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        verify_event(self, e, expected_state=BFDState.up)
+        self.logger.info("BFD: Session is Up")
+        self.test_session.update(state=BFDState.up)
+        self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+
+    def test_session_down(self):
+        """ bring BFD session down """
+        bfd_session_up(self)
+        bfd_session_down(self)
+
+    def test_hold_up(self):
+        """ hold BFD session up """
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            wait_for_bfd_packet(self)
+            self.test_session.send_packet()
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+
+    def test_slow_timer(self):
+        """ verify slow periodic control frames while session down """
+        packet_count = 3
+        self.logger.info("BFD: Waiting for %d BFD packets", packet_count)
+        prev_packet = wait_for_bfd_packet(self, 2)
+        for dummy in range(packet_count):
+            next_packet = wait_for_bfd_packet(self, 2)
+            time_diff = next_packet.time - prev_packet.time
+            # spec says the range should be <0.75, 1>, allow extra 0.05 margin
+            # to work around timing issues
+            self.assert_in_range(
+                time_diff, 0.70, 1.05, "time between slow packets")
+            prev_packet = next_packet
+
+    def test_zero_remote_min_rx(self):
+        """ no packets when zero remote required min rx interval """
+        bfd_session_up(self)
+        self.test_session.update(required_min_rx=0)
+        self.test_session.send_packet()
+        for dummy in range(self.test_session.detect_mult):
+            self.sleep(self.vpp_session.required_min_rx / USEC_IN_SEC,
+                       "sleep before transmitting bfd packet")
+            self.test_session.send_packet()
+            try:
+                p = wait_for_bfd_packet(self, timeout=0)
+                self.logger.error(ppp("Received unexpected packet:", p))
+            except CaptureTimeoutError:
+                pass
+        self.assert_equal(
+            len(self.vapi.collect_events()), 0, "number of bfd events")
+        self.test_session.update(required_min_rx=300000)
+        for dummy in range(3):
+            self.test_session.send_packet()
+            wait_for_bfd_packet(
+                self, timeout=self.test_session.required_min_rx / USEC_IN_SEC)
+        self.assert_equal(
+            len(self.vapi.collect_events()), 0, "number of bfd events")
+
+    def test_conn_down(self):
+        """ verify session goes down after inactivity """
+        bfd_session_up(self)
+        detection_time = self.test_session.detect_mult *\
+            self.vpp_session.required_min_rx / USEC_IN_SEC
+        self.sleep(detection_time, "waiting for BFD session time-out")
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        verify_event(self, e, expected_state=BFDState.down)
+
+    def test_peer_discr_reset_sess_down(self):
+        """ peer discriminator reset after session goes down """
+        bfd_session_up(self)
+        detection_time = self.test_session.detect_mult *\
+            self.vpp_session.required_min_rx / USEC_IN_SEC
+        self.sleep(detection_time, "waiting for BFD session time-out")
+        self.test_session.my_discriminator = 0
+        wait_for_bfd_packet(self,
+                            pcap_time_min=time.time() - self.vpp_clock_offset)
+
+    def test_large_required_min_rx(self):
+        """ large remote required min rx interval """
+        bfd_session_up(self)
+        p = wait_for_bfd_packet(self)
+        interval = 3000000
+        self.test_session.update(required_min_rx=interval)
+        self.test_session.send_packet()
+        time_mark = time.time()
+        count = 0
+        # busy wait here, trying to collect a packet or event, vpp is not
+        # allowed to send packets and the session will timeout first - so the
+        # Up->Down event must arrive before any packets do
+        while time.time() < time_mark + interval / USEC_IN_SEC:
+            try:
+                p = wait_for_bfd_packet(self, timeout=0)
+                # if vpp managed to send a packet before we did the session
+                # session update, then that's fine, ignore it
+                if p.time < time_mark - self.vpp_clock_offset:
+                    continue
+                self.logger.error(ppp("Received unexpected packet:", p))
+                count += 1
+            except CaptureTimeoutError:
+                pass
+            events = self.vapi.collect_events()
+            if len(events) > 0:
+                verify_event(self, events[0], BFDState.down)
+                break
+        self.assert_equal(count, 0, "number of packets received")
+
+    def test_immediate_remote_min_rx_reduction(self):
+        """ immediately honor remote required min rx reduction """
+        self.vpp_session.remove_vpp_config()
+        self.vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, desired_min_tx=10000)
+        self.pg0.enable_capture()
+        self.vpp_session.add_vpp_config()
+        self.test_session.update(desired_min_tx=1000000,
+                                 required_min_rx=1000000)
+        bfd_session_up(self)
+        reference_packet = wait_for_bfd_packet(self)
+        time_mark = time.time()
+        interval = 300000
+        self.test_session.update(required_min_rx=interval)
+        self.test_session.send_packet()
+        extra_time = time.time() - time_mark
+        p = wait_for_bfd_packet(self)
+        # first packet is allowed to be late by time we spent doing the update
+        # calculated in extra_time
+        self.assert_in_range(p.time - reference_packet.time,
+                             .95 * 0.75 * interval / USEC_IN_SEC,
+                             1.05 * interval / USEC_IN_SEC + extra_time,
+                             "time between BFD packets")
+        reference_packet = p
+        for dummy in range(3):
+            p = wait_for_bfd_packet(self)
+            diff = p.time - reference_packet.time
+            self.assert_in_range(diff, .95 * .75 * interval / USEC_IN_SEC,
+                                 1.05 * interval / USEC_IN_SEC,
+                                 "time between BFD packets")
+            reference_packet = p
+
+    def test_modify_req_min_rx_double(self):
+        """ modify session - double required min rx """
+        bfd_session_up(self)
+        p = wait_for_bfd_packet(self)
+        self.test_session.update(desired_min_tx=10000,
+                                 required_min_rx=10000)
+        self.test_session.send_packet()
+        # double required min rx
+        self.vpp_session.modify_parameters(
+            required_min_rx=2 * self.vpp_session.required_min_rx)
+        p = wait_for_bfd_packet(
+            self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        # poll bit needs to be set
+        self.assertIn("P", p.sprintf("%BFD.flags%"),
+                      "Poll bit not set in BFD packet")
+        # finish poll sequence with final packet
+        final = self.test_session.create_packet()
+        final[BFD].flags = "F"
+        timeout = self.test_session.detect_mult * \
+            max(self.test_session.desired_min_tx,
+                self.vpp_session.required_min_rx) / USEC_IN_SEC
+        self.test_session.send_packet(final)
+        time_mark = time.time()
+        e = self.vapi.wait_for_event(2 * timeout, "bfd_udp_session_details")
+        verify_event(self, e, expected_state=BFDState.down)
+        time_to_event = time.time() - time_mark
+        self.assert_in_range(time_to_event, .9 * timeout,
+                             1.1 * timeout, "session timeout")
+
+    def test_modify_req_min_rx_halve(self):
+        """ modify session - halve required min rx """
+        self.vpp_session.modify_parameters(
+            required_min_rx=2 * self.vpp_session.required_min_rx)
+        bfd_session_up(self)
+        p = wait_for_bfd_packet(self)
+        self.test_session.update(desired_min_tx=10000,
+                                 required_min_rx=10000)
+        self.test_session.send_packet()
+        p = wait_for_bfd_packet(
+            self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        # halve required min rx
+        old_required_min_rx = self.vpp_session.required_min_rx
+        self.vpp_session.modify_parameters(
+            required_min_rx=self.vpp_session.required_min_rx // 2)
+        # now we wait 0.8*3*old-req-min-rx and the session should still be up
+        self.sleep(0.8 * self.vpp_session.detect_mult *
+                   old_required_min_rx / USEC_IN_SEC,
+                   "wait before finishing poll sequence")
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+        p = wait_for_bfd_packet(self)
+        # poll bit needs to be set
+        self.assertIn("P", p.sprintf("%BFD.flags%"),
+                      "Poll bit not set in BFD packet")
+        # finish poll sequence with final packet
+        final = self.test_session.create_packet()
+        final[BFD].flags = "F"
+        self.test_session.send_packet(final)
+        # now the session should time out under new conditions
+        detection_time = self.test_session.detect_mult *\
+            self.vpp_session.required_min_rx / USEC_IN_SEC
+        before = time.time()
+        e = self.vapi.wait_for_event(
+            2 * detection_time, "bfd_udp_session_details")
+        after = time.time()
+        self.assert_in_range(after - before,
+                             0.9 * detection_time,
+                             1.1 * detection_time,
+                             "time before bfd session goes down")
+        verify_event(self, e, expected_state=BFDState.down)
+
+    def test_modify_detect_mult(self):
+        """ modify detect multiplier """
+        bfd_session_up(self)
+        p = wait_for_bfd_packet(self)
+        self.vpp_session.modify_parameters(detect_mult=1)
+        p = wait_for_bfd_packet(
+            self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assert_equal(self.vpp_session.detect_mult,
+                          p[BFD].detect_mult,
+                          "detect mult")
+        # poll bit must not be set
+        self.assertNotIn("P", p.sprintf("%BFD.flags%"),
+                         "Poll bit not set in BFD packet")
+        self.vpp_session.modify_parameters(detect_mult=10)
+        p = wait_for_bfd_packet(
+            self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assert_equal(self.vpp_session.detect_mult,
+                          p[BFD].detect_mult,
+                          "detect mult")
+        # poll bit must not be set
+        self.assertNotIn("P", p.sprintf("%BFD.flags%"),
+                         "Poll bit not set in BFD packet")
+
+    def test_queued_poll(self):
+        """ test poll sequence queueing """
+        bfd_session_up(self)
+        p = wait_for_bfd_packet(self)
+        self.vpp_session.modify_parameters(
+            required_min_rx=2 * self.vpp_session.required_min_rx)
+        p = wait_for_bfd_packet(self)
+        poll_sequence_start = time.time()
+        poll_sequence_length_min = 0.5
+        send_final_after = time.time() + poll_sequence_length_min
+        # poll bit needs to be set
+        self.assertIn("P", p.sprintf("%BFD.flags%"),
+                      "Poll bit not set in BFD packet")
+        self.assert_equal(p[BFD].required_min_rx_interval,
+                          self.vpp_session.required_min_rx,
+                          "BFD required min rx interval")
+        self.vpp_session.modify_parameters(
+            required_min_rx=2 * self.vpp_session.required_min_rx)
+        # 2nd poll sequence should be queued now
+        # don't send the reply back yet, wait for some time to emulate
+        # longer round-trip time
+        packet_count = 0
+        while time.time() < send_final_after:
+            self.test_session.send_packet()
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(len(self.vapi.collect_events()), 0,
+                              "number of bfd events")
+            self.assert_equal(p[BFD].required_min_rx_interval,
+                              self.vpp_session.required_min_rx,
+                              "BFD required min rx interval")
+            packet_count += 1
+            # poll bit must be set
+            self.assertIn("P", p.sprintf("%BFD.flags%"),
+                          "Poll bit not set in BFD packet")
+        final = self.test_session.create_packet()
+        final[BFD].flags = "F"
+        self.test_session.send_packet(final)
+        # finish 1st with final
+        poll_sequence_length = time.time() - poll_sequence_start
+        # vpp must wait for some time before starting new poll sequence
+        poll_no_2_started = False
+        for dummy in range(2 * packet_count):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(len(self.vapi.collect_events()), 0,
+                              "number of bfd events")
+            if "P" in p.sprintf("%BFD.flags%"):
+                poll_no_2_started = True
+                if time.time() < poll_sequence_start + poll_sequence_length:
+                    raise Exception("VPP started 2nd poll sequence too soon")
+                final = self.test_session.create_packet()
+                final[BFD].flags = "F"
+                self.test_session.send_packet(final)
+                break
+            else:
+                self.test_session.send_packet()
+        self.assertTrue(poll_no_2_started, "2nd poll sequence not performed")
+        # finish 2nd with final
+        final = self.test_session.create_packet()
+        final[BFD].flags = "F"
+        self.test_session.send_packet(final)
+        p = wait_for_bfd_packet(self)
+        # poll bit must not be set
+        self.assertNotIn("P", p.sprintf("%BFD.flags%"),
+                         "Poll bit set in BFD packet")
+
+    # returning inconsistent results requiring retries in per-patch tests
+    @unittest.skipUnless(running_extended_tests, "part of extended tests")
+    def test_poll_response(self):
+        """ test correct response to control frame with poll bit set """
+        bfd_session_up(self)
+        poll = self.test_session.create_packet()
+        poll[BFD].flags = "P"
+        self.test_session.send_packet(poll)
+        final = wait_for_bfd_packet(
+            self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assertIn("F", final.sprintf("%BFD.flags%"))
+
+    def test_no_periodic_if_remote_demand(self):
+        """ no periodic frames outside poll sequence if remote demand set """
+        bfd_session_up(self)
+        demand = self.test_session.create_packet()
+        demand[BFD].flags = "D"
+        self.test_session.send_packet(demand)
+        transmit_time = 0.9 \
+            * max(self.vpp_session.required_min_rx,
+                  self.test_session.desired_min_tx) \
+            / USEC_IN_SEC
+        count = 0
+        for dummy in range(self.test_session.detect_mult * 2):
+            self.sleep(transmit_time)
+            self.test_session.send_packet(demand)
+            try:
+                p = wait_for_bfd_packet(self, timeout=0)
+                self.logger.error(ppp("Received unexpected packet:", p))
+                count += 1
+            except CaptureTimeoutError:
+                pass
+        events = self.vapi.collect_events()
+        for e in events:
+            self.logger.error("Received unexpected event: %s", e)
+        self.assert_equal(count, 0, "number of packets received")
+        self.assert_equal(len(events), 0, "number of events received")
+
+    def test_echo_looped_back(self):
+        """ echo packets looped back """
+        # don't need a session in this case..
+        self.vpp_session.remove_vpp_config()
+        self.pg0.enable_capture()
+        echo_packet_count = 10
+        # random source port low enough to increment a few times..
+        udp_sport_tx = randint(1, 50000)
+        udp_sport_rx = udp_sport_tx
+        echo_packet = (Ether(src=self.pg0.remote_mac,
+                             dst=self.pg0.local_mac) /
+                       IP(src=self.pg0.remote_ip4,
+                          dst=self.pg0.remote_ip4) /
+                       UDP(dport=BFD.udp_dport_echo) /
+                       Raw("this should be looped back"))
+        for dummy in range(echo_packet_count):
+            self.sleep(.01, "delay between echo packets")
+            echo_packet[UDP].sport = udp_sport_tx
+            udp_sport_tx += 1
+            self.logger.debug(ppp("Sending packet:", echo_packet))
+            self.pg0.add_stream(echo_packet)
+            self.pg_start()
+        for dummy in range(echo_packet_count):
+            p = self.pg0.wait_for_packet(1)
+            self.logger.debug(ppp("Got packet:", p))
+            ether = p[Ether]
+            self.assert_equal(self.pg0.remote_mac,
+                              ether.dst, "Destination MAC")
+            self.assert_equal(self.pg0.local_mac, ether.src, "Source MAC")
+            ip = p[IP]
+            self.assert_equal(self.pg0.remote_ip4, ip.dst, "Destination IP")
+            self.assert_equal(self.pg0.remote_ip4, ip.src, "Destination IP")
+            udp = p[UDP]
+            self.assert_equal(udp.dport, BFD.udp_dport_echo,
+                              "UDP destination port")
+            self.assert_equal(udp.sport, udp_sport_rx, "UDP source port")
+            udp_sport_rx += 1
+            # need to compare the hex payload here, otherwise BFD_vpp_echo
+            # gets in way
+            self.assertEqual(scapy.compat.raw(p[UDP].payload),
+                             scapy.compat.raw(echo_packet[UDP].payload),
+                             "Received packet is not the echo packet sent")
+        self.assert_equal(udp_sport_tx, udp_sport_rx, "UDP source port (== "
+                          "ECHO packet identifier for test purposes)")
+
+    def test_echo(self):
+        """ echo function """
+        bfd_session_up(self)
+        self.test_session.update(required_min_echo_rx=150000)
+        self.test_session.send_packet()
+        detection_time = self.test_session.detect_mult *\
+            self.vpp_session.required_min_rx / USEC_IN_SEC
+        # echo shouldn't work without echo source set
+        for dummy in range(10):
+            sleep = self.vpp_session.required_min_rx / USEC_IN_SEC
+            self.sleep(sleep, "delay before sending bfd packet")
+            self.test_session.send_packet()
+        p = wait_for_bfd_packet(
+            self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assert_equal(p[BFD].required_min_rx_interval,
+                          self.vpp_session.required_min_rx,
+                          "BFD required min rx interval")
+        self.test_session.send_packet()
+        self.vapi.bfd_udp_set_echo_source(
+            sw_if_index=self.loopback0.sw_if_index)
+        echo_seen = False
+        # should be turned on - loopback echo packets
+        for dummy in range(3):
+            loop_until = time.time() + 0.75 * detection_time
+            while time.time() < loop_until:
+                p = self.pg0.wait_for_packet(1)
+                self.logger.debug(ppp("Got packet:", p))
+                if p[UDP].dport == BFD.udp_dport_echo:
+                    self.assert_equal(
+                        p[IP].dst, self.pg0.local_ip4, "BFD ECHO dst IP")
+                    self.assertNotEqual(p[IP].src, self.loopback0.local_ip4,
+                                        "BFD ECHO src IP equal to loopback IP")
+                    self.logger.debug(ppp("Looping back packet:", p))
+                    self.assert_equal(p[Ether].dst, self.pg0.remote_mac,
+                                      "ECHO packet destination MAC address")
+                    p[Ether].dst = self.pg0.local_mac
+                    self.pg0.add_stream(p)
+                    self.pg_start()
+                    echo_seen = True
+                elif p.haslayer(BFD):
+                    if echo_seen:
+                        self.assertGreaterEqual(
+                            p[BFD].required_min_rx_interval,
+                            1000000)
+                    if "P" in p.sprintf("%BFD.flags%"):
+                        final = self.test_session.create_packet()
+                        final[BFD].flags = "F"
+                        self.test_session.send_packet(final)
+                else:
+                    raise Exception(ppp("Received unknown packet:", p))
+
+                self.assert_equal(len(self.vapi.collect_events()), 0,
+                                  "number of bfd events")
+            self.test_session.send_packet()
+        self.assertTrue(echo_seen, "No echo packets received")
+
+    def test_echo_fail(self):
+        """ session goes down if echo function fails """
+        bfd_session_up(self)
+        self.test_session.update(required_min_echo_rx=150000)
+        self.test_session.send_packet()
+        detection_time = self.test_session.detect_mult *\
+            self.vpp_session.required_min_rx / USEC_IN_SEC
+        self.vapi.bfd_udp_set_echo_source(
+            sw_if_index=self.loopback0.sw_if_index)
+        # echo function should be used now, but we will drop the echo packets
+        verified_diag = False
+        for dummy in range(3):
+            loop_until = time.time() + 0.75 * detection_time
+            while time.time() < loop_until:
+                p = self.pg0.wait_for_packet(1)
+                self.logger.debug(ppp("Got packet:", p))
+                if p[UDP].dport == BFD.udp_dport_echo:
+                    # dropped
+                    pass
+                elif p.haslayer(BFD):
+                    if "P" in p.sprintf("%BFD.flags%"):
+                        self.assertGreaterEqual(
+                            p[BFD].required_min_rx_interval,
+                            1000000)
+                        final = self.test_session.create_packet()
+                        final[BFD].flags = "F"
+                        self.test_session.send_packet(final)
+                    if p[BFD].state == BFDState.down:
+                        self.assert_equal(p[BFD].diag,
+                                          BFDDiagCode.echo_function_failed,
+                                          BFDDiagCode)
+                        verified_diag = True
+                else:
+                    raise Exception(ppp("Received unknown packet:", p))
+            self.test_session.send_packet()
+        events = self.vapi.collect_events()
+        self.assert_equal(len(events), 1, "number of bfd events")
+        self.assert_equal(events[0].state, BFDState.down, BFDState)
+        self.assertTrue(verified_diag, "Incorrect diagnostics code received")
+
+    def test_echo_stop(self):
+        """ echo function stops if peer sets required min echo rx zero """
+        bfd_session_up(self)
+        self.test_session.update(required_min_echo_rx=150000)
+        self.test_session.send_packet()
+        self.vapi.bfd_udp_set_echo_source(
+            sw_if_index=self.loopback0.sw_if_index)
+        # wait for first echo packet
+        while True:
+            p = self.pg0.wait_for_packet(1)
+            self.logger.debug(ppp("Got packet:", p))
+            if p[UDP].dport == BFD.udp_dport_echo:
+                self.logger.debug(ppp("Looping back packet:", p))
+                p[Ether].dst = self.pg0.local_mac
+                self.pg0.add_stream(p)
+                self.pg_start()
+                break
+            elif p.haslayer(BFD):
+                # ignore BFD
+                pass
+            else:
+                raise Exception(ppp("Received unknown packet:", p))
+        self.test_session.update(required_min_echo_rx=0)
+        self.test_session.send_packet()
+        # echo packets shouldn't arrive anymore
+        for dummy in range(5):
+            wait_for_bfd_packet(
+                self, pcap_time_min=time.time() - self.vpp_clock_offset)
+            self.test_session.send_packet()
+            events = self.vapi.collect_events()
+            self.assert_equal(len(events), 0, "number of bfd events")
+
+    def test_echo_source_removed(self):
+        """ echo function stops if echo source is removed """
+        bfd_session_up(self)
+        self.test_session.update(required_min_echo_rx=150000)
+        self.test_session.send_packet()
+        self.vapi.bfd_udp_set_echo_source(
+            sw_if_index=self.loopback0.sw_if_index)
+        # wait for first echo packet
+        while True:
+            p = self.pg0.wait_for_packet(1)
+            self.logger.debug(ppp("Got packet:", p))
+            if p[UDP].dport == BFD.udp_dport_echo:
+                self.logger.debug(ppp("Looping back packet:", p))
+                p[Ether].dst = self.pg0.local_mac
+                self.pg0.add_stream(p)
+                self.pg_start()
+                break
+            elif p.haslayer(BFD):
+                # ignore BFD
+                pass
+            else:
+                raise Exception(ppp("Received unknown packet:", p))
+        self.vapi.bfd_udp_del_echo_source()
+        self.test_session.send_packet()
+        # echo packets shouldn't arrive anymore
+        for dummy in range(5):
+            wait_for_bfd_packet(
+                self, pcap_time_min=time.time() - self.vpp_clock_offset)
+            self.test_session.send_packet()
+            events = self.vapi.collect_events()
+            self.assert_equal(len(events), 0, "number of bfd events")
+
+    def test_stale_echo(self):
+        """ stale echo packets don't keep a session up """
+        bfd_session_up(self)
+        self.test_session.update(required_min_echo_rx=150000)
+        self.vapi.bfd_udp_set_echo_source(
+            sw_if_index=self.loopback0.sw_if_index)
+        self.test_session.send_packet()
+        # should be turned on - loopback echo packets
+        echo_packet = None
+        timeout_at = None
+        timeout_ok = False
+        for dummy in range(10 * self.vpp_session.detect_mult):
+            p = self.pg0.wait_for_packet(1)
+            if p[UDP].dport == BFD.udp_dport_echo:
+                if echo_packet is None:
+                    self.logger.debug(ppp("Got first echo packet:", p))
+                    echo_packet = p
+                    timeout_at = time.time() + self.vpp_session.detect_mult * \
+                        self.test_session.required_min_echo_rx / USEC_IN_SEC
+                else:
+                    self.logger.debug(ppp("Got followup echo packet:", p))
+                self.logger.debug(ppp("Looping back first echo packet:", p))
+                echo_packet[Ether].dst = self.pg0.local_mac
+                self.pg0.add_stream(echo_packet)
+                self.pg_start()
+            elif p.haslayer(BFD):
+                self.logger.debug(ppp("Got packet:", p))
+                if "P" in p.sprintf("%BFD.flags%"):
+                    final = self.test_session.create_packet()
+                    final[BFD].flags = "F"
+                    self.test_session.send_packet(final)
+                if p[BFD].state == BFDState.down:
+                    self.assertIsNotNone(
+                        timeout_at,
+                        "Session went down before first echo packet received")
+                    now = time.time()
+                    self.assertGreaterEqual(
+                        now, timeout_at,
+                        "Session timeout at %s, but is expected at %s" %
+                        (now, timeout_at))
+                    self.assert_equal(p[BFD].diag,
+                                      BFDDiagCode.echo_function_failed,
+                                      BFDDiagCode)
+                    events = self.vapi.collect_events()
+                    self.assert_equal(len(events), 1, "number of bfd events")
+                    self.assert_equal(events[0].state, BFDState.down, BFDState)
+                    timeout_ok = True
+                    break
+            else:
+                raise Exception(ppp("Received unknown packet:", p))
+            self.test_session.send_packet()
+        self.assertTrue(timeout_ok, "Expected timeout event didn't occur")
+
+    def test_invalid_echo_checksum(self):
+        """ echo packets with invalid checksum don't keep a session up """
+        bfd_session_up(self)
+        self.test_session.update(required_min_echo_rx=150000)
+        self.vapi.bfd_udp_set_echo_source(
+            sw_if_index=self.loopback0.sw_if_index)
+        self.test_session.send_packet()
+        # should be turned on - loopback echo packets
+        timeout_at = None
+        timeout_ok = False
+        for dummy in range(10 * self.vpp_session.detect_mult):
+            p = self.pg0.wait_for_packet(1)
+            if p[UDP].dport == BFD.udp_dport_echo:
+                self.logger.debug(ppp("Got echo packet:", p))
+                if timeout_at is None:
+                    timeout_at = time.time() + self.vpp_session.detect_mult * \
+                        self.test_session.required_min_echo_rx / USEC_IN_SEC
+                p[BFD_vpp_echo].checksum = getrandbits(64)
+                p[Ether].dst = self.pg0.local_mac
+                self.logger.debug(ppp("Looping back modified echo packet:", p))
+                self.pg0.add_stream(p)
+                self.pg_start()
+            elif p.haslayer(BFD):
+                self.logger.debug(ppp("Got packet:", p))
+                if "P" in p.sprintf("%BFD.flags%"):
+                    final = self.test_session.create_packet()
+                    final[BFD].flags = "F"
+                    self.test_session.send_packet(final)
+                if p[BFD].state == BFDState.down:
+                    self.assertIsNotNone(
+                        timeout_at,
+                        "Session went down before first echo packet received")
+                    now = time.time()
+                    self.assertGreaterEqual(
+                        now, timeout_at,
+                        "Session timeout at %s, but is expected at %s" %
+                        (now, timeout_at))
+                    self.assert_equal(p[BFD].diag,
+                                      BFDDiagCode.echo_function_failed,
+                                      BFDDiagCode)
+                    events = self.vapi.collect_events()
+                    self.assert_equal(len(events), 1, "number of bfd events")
+                    self.assert_equal(events[0].state, BFDState.down, BFDState)
+                    timeout_ok = True
+                    break
+            else:
+                raise Exception(ppp("Received unknown packet:", p))
+            self.test_session.send_packet()
+        self.assertTrue(timeout_ok, "Expected timeout event didn't occur")
+
+    def test_admin_up_down(self):
+        """ put session admin-up and admin-down """
+        bfd_session_up(self)
+        self.vpp_session.admin_down()
+        self.pg0.enable_capture()
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        verify_event(self, e, expected_state=BFDState.admin_down)
+        for dummy in range(2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.admin_down, BFDState)
+        # try to bring session up - shouldn't be possible
+        self.test_session.update(state=BFDState.init)
+        self.test_session.send_packet()
+        for dummy in range(2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.admin_down, BFDState)
+        self.vpp_session.admin_up()
+        self.test_session.update(state=BFDState.down)
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        verify_event(self, e, expected_state=BFDState.down)
+        p = wait_for_bfd_packet(
+            self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assert_equal(p[BFD].state, BFDState.down, BFDState)
+        self.test_session.send_packet()
+        p = wait_for_bfd_packet(
+            self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assert_equal(p[BFD].state, BFDState.init, BFDState)
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        verify_event(self, e, expected_state=BFDState.init)
+        self.test_session.update(state=BFDState.up)
+        self.test_session.send_packet()
+        p = wait_for_bfd_packet(
+            self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        verify_event(self, e, expected_state=BFDState.up)
+
+    def test_config_change_remote_demand(self):
+        """ configuration change while peer in demand mode """
+        bfd_session_up(self)
+        demand = self.test_session.create_packet()
+        demand[BFD].flags = "D"
+        self.test_session.send_packet(demand)
+        self.vpp_session.modify_parameters(
+            required_min_rx=2 * self.vpp_session.required_min_rx)
+        p = wait_for_bfd_packet(
+            self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        # poll bit must be set
+        self.assertIn("P", p.sprintf("%BFD.flags%"), "Poll bit not set")
+        # terminate poll sequence
+        final = self.test_session.create_packet()
+        final[BFD].flags = "D+F"
+        self.test_session.send_packet(final)
+        # vpp should be quiet now again
+        transmit_time = 0.9 \
+            * max(self.vpp_session.required_min_rx,
+                  self.test_session.desired_min_tx) \
+            / USEC_IN_SEC
+        count = 0
+        for dummy in range(self.test_session.detect_mult * 2):
+            self.sleep(transmit_time)
+            self.test_session.send_packet(demand)
+            try:
+                p = wait_for_bfd_packet(self, timeout=0)
+                self.logger.error(ppp("Received unexpected packet:", p))
+                count += 1
+            except CaptureTimeoutError:
+                pass
+        events = self.vapi.collect_events()
+        for e in events:
+            self.logger.error("Received unexpected event: %s", e)
+        self.assert_equal(count, 0, "number of packets received")
+        self.assert_equal(len(events), 0, "number of events received")
+
+    def test_intf_deleted(self):
+        """ interface with bfd session deleted """
+        intf = VppLoInterface(self)
+        intf.config_ip4()
+        intf.admin_up()
+        sw_if_index = intf.sw_if_index
+        vpp_session = VppBFDUDPSession(self, intf, intf.remote_ip4)
+        vpp_session.add_vpp_config()
+        vpp_session.admin_up()
+        intf.remove_vpp_config()
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        self.assert_equal(e.sw_if_index, sw_if_index, "sw_if_index")
+        self.assertFalse(vpp_session.query_vpp_config())
+
+
+class BFD6TestCase(VppTestCase):
+    """Bidirectional Forwarding Detection (BFD) (IPv6) """
+
+    pg0 = None
+    vpp_clock_offset = None
+    vpp_session = None
+    test_session = None
+
+    @classmethod
+    def force_solo(cls):
+        return True
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFD6TestCase, cls).setUpClass()
+        cls.vapi.cli("set log class bfd level debug")
+        try:
+            cls.create_pg_interfaces([0])
+            cls.pg0.config_ip6()
+            cls.pg0.configure_ipv6_neighbors()
+            cls.pg0.admin_up()
+            cls.pg0.resolve_ndp()
+            cls.create_loopback_interfaces(1)
+            cls.loopback0 = cls.lo_interfaces[0]
+            cls.loopback0.config_ip6()
+            cls.loopback0.admin_up()
+
+        except Exception:
+            super(BFD6TestCase, cls).tearDownClass()
+            raise
+
+    @classmethod
+    def tearDownClass(cls):
+        super(BFD6TestCase, cls).tearDownClass()
+
+    def setUp(self):
+        super(BFD6TestCase, self).setUp()
+        self.factory = AuthKeyFactory()
+        self.vapi.want_bfd_events()
+        self.pg0.enable_capture()
+        try:
+            self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                                self.pg0.remote_ip6,
+                                                af=AF_INET6)
+            self.vpp_session.add_vpp_config()
+            self.vpp_session.admin_up()
+            self.test_session = BFDTestSession(self, self.pg0, AF_INET6)
+            self.logger.debug(self.vapi.cli("show adj nbr"))
+        except BaseException:
+            self.vapi.want_bfd_events(enable_disable=0)
+            raise
+
+    def tearDown(self):
+        if not self.vpp_dead:
+            self.vapi.want_bfd_events(enable_disable=0)
+        self.vapi.collect_events()  # clear the event queue
+        super(BFD6TestCase, self).tearDown()
+
+    def test_session_up(self):
+        """ bring BFD session up """
+        bfd_session_up(self)
+
+    def test_session_up_by_ip(self):
+        """ bring BFD session up - first frame looked up by address pair """
+        self.logger.info("BFD: Sending Slow control frame")
+        self.test_session.update(my_discriminator=randint(0, 40000000))
+        self.test_session.send_packet()
+        self.pg0.enable_capture()
+        p = self.pg0.wait_for_packet(1)
+        self.assert_equal(p[BFD].your_discriminator,
+                          self.test_session.my_discriminator,
+                          "BFD - your discriminator")
+        self.assert_equal(p[BFD].state, BFDState.init, BFDState)
+        self.test_session.update(your_discriminator=p[BFD].my_discriminator,
+                                 state=BFDState.up)
+        self.logger.info("BFD: Waiting for event")
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        verify_event(self, e, expected_state=BFDState.init)
+        self.logger.info("BFD: Sending Up")
+        self.test_session.send_packet()
+        self.logger.info("BFD: Waiting for event")
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        verify_event(self, e, expected_state=BFDState.up)
+        self.logger.info("BFD: Session is Up")
+        self.test_session.update(state=BFDState.up)
+        self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+
+    def test_hold_up(self):
+        """ hold BFD session up """
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            wait_for_bfd_packet(self)
+            self.test_session.send_packet()
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+
+    def test_echo_looped_back(self):
+        """ echo packets looped back """
+        # don't need a session in this case..
+        self.vpp_session.remove_vpp_config()
+        self.pg0.enable_capture()
+        echo_packet_count = 10
+        # random source port low enough to increment a few times..
+        udp_sport_tx = randint(1, 50000)
+        udp_sport_rx = udp_sport_tx
+        echo_packet = (Ether(src=self.pg0.remote_mac,
+                             dst=self.pg0.local_mac) /
+                       IPv6(src=self.pg0.remote_ip6,
+                            dst=self.pg0.remote_ip6) /
+                       UDP(dport=BFD.udp_dport_echo) /
+                       Raw("this should be looped back"))
+        for dummy in range(echo_packet_count):
+            self.sleep(.01, "delay between echo packets")
+            echo_packet[UDP].sport = udp_sport_tx
+            udp_sport_tx += 1
+            self.logger.debug(ppp("Sending packet:", echo_packet))
+            self.pg0.add_stream(echo_packet)
+            self.pg_start()
+        for dummy in range(echo_packet_count):
+            p = self.pg0.wait_for_packet(1)
+            self.logger.debug(ppp("Got packet:", p))
+            ether = p[Ether]
+            self.assert_equal(self.pg0.remote_mac,
+                              ether.dst, "Destination MAC")
+            self.assert_equal(self.pg0.local_mac, ether.src, "Source MAC")
+            ip = p[IPv6]
+            self.assert_equal(self.pg0.remote_ip6, ip.dst, "Destination IP")
+            self.assert_equal(self.pg0.remote_ip6, ip.src, "Destination IP")
+            udp = p[UDP]
+            self.assert_equal(udp.dport, BFD.udp_dport_echo,
+                              "UDP destination port")
+            self.assert_equal(udp.sport, udp_sport_rx, "UDP source port")
+            udp_sport_rx += 1
+            # need to compare the hex payload here, otherwise BFD_vpp_echo
+            # gets in way
+            self.assertEqual(scapy.compat.raw(p[UDP].payload),
+                             scapy.compat.raw(echo_packet[UDP].payload),
+                             "Received packet is not the echo packet sent")
+        self.assert_equal(udp_sport_tx, udp_sport_rx, "UDP source port (== "
+                          "ECHO packet identifier for test purposes)")
+        self.assert_equal(udp_sport_tx, udp_sport_rx, "UDP source port (== "
+                          "ECHO packet identifier for test purposes)")
+
+    def test_echo(self):
+        """ echo function """
+        bfd_session_up(self)
+        self.test_session.update(required_min_echo_rx=150000)
+        self.test_session.send_packet()
+        detection_time = self.test_session.detect_mult *\
+            self.vpp_session.required_min_rx / USEC_IN_SEC
+        # echo shouldn't work without echo source set
+        for dummy in range(10):
+            sleep = self.vpp_session.required_min_rx / USEC_IN_SEC
+            self.sleep(sleep, "delay before sending bfd packet")
+            self.test_session.send_packet()
+        p = wait_for_bfd_packet(
+            self, pcap_time_min=time.time() - self.vpp_clock_offset)
+        self.assert_equal(p[BFD].required_min_rx_interval,
+                          self.vpp_session.required_min_rx,
+                          "BFD required min rx interval")
+        self.test_session.send_packet()
+        self.vapi.bfd_udp_set_echo_source(
+            sw_if_index=self.loopback0.sw_if_index)
+        echo_seen = False
+        # should be turned on - loopback echo packets
+        for dummy in range(3):
+            loop_until = time.time() + 0.75 * detection_time
+            while time.time() < loop_until:
+                p = self.pg0.wait_for_packet(1)
+                self.logger.debug(ppp("Got packet:", p))
+                if p[UDP].dport == BFD.udp_dport_echo:
+                    self.assert_equal(
+                        p[IPv6].dst, self.pg0.local_ip6, "BFD ECHO dst IP")
+                    self.assertNotEqual(p[IPv6].src, self.loopback0.local_ip6,
+                                        "BFD ECHO src IP equal to loopback IP")
+                    self.logger.debug(ppp("Looping back packet:", p))
+                    self.assert_equal(p[Ether].dst, self.pg0.remote_mac,
+                                      "ECHO packet destination MAC address")
+                    p[Ether].dst = self.pg0.local_mac
+                    self.pg0.add_stream(p)
+                    self.pg_start()
+                    echo_seen = True
+                elif p.haslayer(BFD):
+                    if echo_seen:
+                        self.assertGreaterEqual(
+                            p[BFD].required_min_rx_interval,
+                            1000000)
+                    if "P" in p.sprintf("%BFD.flags%"):
+                        final = self.test_session.create_packet()
+                        final[BFD].flags = "F"
+                        self.test_session.send_packet(final)
+                else:
+                    raise Exception(ppp("Received unknown packet:", p))
+
+                self.assert_equal(len(self.vapi.collect_events()), 0,
+                                  "number of bfd events")
+            self.test_session.send_packet()
+        self.assertTrue(echo_seen, "No echo packets received")
+
+    def test_intf_deleted(self):
+        """ interface with bfd session deleted """
+        intf = VppLoInterface(self)
+        intf.config_ip6()
+        intf.admin_up()
+        sw_if_index = intf.sw_if_index
+        vpp_session = VppBFDUDPSession(
+            self, intf, intf.remote_ip6, af=AF_INET6)
+        vpp_session.add_vpp_config()
+        vpp_session.admin_up()
+        intf.remove_vpp_config()
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        self.assert_equal(e.sw_if_index, sw_if_index, "sw_if_index")
+        self.assertFalse(vpp_session.query_vpp_config())
+
+
+class BFDFIBTestCase(VppTestCase):
+    """ BFD-FIB interactions (IPv6) """
+
+    vpp_session = None
+    test_session = None
+
+    @classmethod
+    def force_solo(cls):
+        return True
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFDFIBTestCase, cls).setUpClass()
+
+    @classmethod
+    def tearDownClass(cls):
+        super(BFDFIBTestCase, cls).tearDownClass()
+
+    def setUp(self):
+        super(BFDFIBTestCase, self).setUp()
+        self.create_pg_interfaces(range(1))
+
+        self.vapi.want_bfd_events()
+        self.pg0.enable_capture()
+
+        for i in self.pg_interfaces:
+            i.admin_up()
+            i.config_ip6()
+            i.configure_ipv6_neighbors()
+
+    def tearDown(self):
+        if not self.vpp_dead:
+            self.vapi.want_bfd_events(enable_disable=False)
+
+        super(BFDFIBTestCase, self).tearDown()
+
+    @staticmethod
+    def pkt_is_not_data_traffic(p):
+        """ not data traffic implies BFD or the usual IPv6 ND/RA"""
+        if p.haslayer(BFD) or is_ipv6_misc(p):
+            return True
+        return False
+
+    def test_session_with_fib(self):
+        """ BFD-FIB interactions """
+
+        # packets to match against both of the routes
+        p = [(Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+              IPv6(src="3001::1", dst="2001::1") /
+              UDP(sport=1234, dport=1234) /
+              Raw(b'\xa5' * 100)),
+             (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+              IPv6(src="3001::1", dst="2002::1") /
+              UDP(sport=1234, dport=1234) /
+              Raw(b'\xa5' * 100))]
+
+        # A recursive and a non-recursive route via a next-hop that
+        # will have a BFD session
+        ip_2001_s_64 = VppIpRoute(self, "2001::", 64,
+                                  [VppRoutePath(self.pg0.remote_ip6,
+                                                self.pg0.sw_if_index)])
+        ip_2002_s_64 = VppIpRoute(self, "2002::", 64,
+                                  [VppRoutePath(self.pg0.remote_ip6,
+                                                0xffffffff)])
+        ip_2001_s_64.add_vpp_config()
+        ip_2002_s_64.add_vpp_config()
+
+        # bring the session up now the routes are present
+        self.vpp_session = VppBFDUDPSession(self,
+                                            self.pg0,
+                                            self.pg0.remote_ip6,
+                                            af=AF_INET6)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(self, self.pg0, AF_INET6)
+
+        # session is up - traffic passes
+        bfd_session_up(self)
+
+        self.pg0.add_stream(p)
+        self.pg_start()
+        for packet in p:
+            captured = self.pg0.wait_for_packet(
+                1,
+                filter_out_fn=self.pkt_is_not_data_traffic)
+            self.assertEqual(captured[IPv6].dst,
+                             packet[IPv6].dst)
+
+        # session is up - traffic is dropped
+        bfd_session_down(self)
+
+        self.pg0.add_stream(p)
+        self.pg_start()
+        with self.assertRaises(CaptureTimeoutError):
+            self.pg0.wait_for_packet(1, self.pkt_is_not_data_traffic)
+
+        # session is up - traffic passes
+        bfd_session_up(self)
+
+        self.pg0.add_stream(p)
+        self.pg_start()
+        for packet in p:
+            captured = self.pg0.wait_for_packet(
+                1,
+                filter_out_fn=self.pkt_is_not_data_traffic)
+            self.assertEqual(captured[IPv6].dst,
+                             packet[IPv6].dst)
+
+
+@unittest.skipUnless(running_extended_tests, "part of extended tests")
+class BFDTunTestCase(VppTestCase):
+    """ BFD over GRE tunnel """
+
+    vpp_session = None
+    test_session = None
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFDTunTestCase, cls).setUpClass()
+
+    @classmethod
+    def tearDownClass(cls):
+        super(BFDTunTestCase, cls).tearDownClass()
+
+    def setUp(self):
+        super(BFDTunTestCase, self).setUp()
+        self.create_pg_interfaces(range(1))
+
+        self.vapi.want_bfd_events()
+        self.pg0.enable_capture()
+
+        for i in self.pg_interfaces:
+            i.admin_up()
+            i.config_ip4()
+            i.resolve_arp()
+
+    def tearDown(self):
+        if not self.vpp_dead:
+            self.vapi.want_bfd_events(enable_disable=0)
+
+        super(BFDTunTestCase, self).tearDown()
+
+    @staticmethod
+    def pkt_is_not_data_traffic(p):
+        """ not data traffic implies BFD or the usual IPv6 ND/RA"""
+        if p.haslayer(BFD) or is_ipv6_misc(p):
+            return True
+        return False
+
+    def test_bfd_o_gre(self):
+        """ BFD-o-GRE  """
+
+        # A GRE interface over which to run a BFD session
+        gre_if = VppGreInterface(self,
+                                 self.pg0.local_ip4,
+                                 self.pg0.remote_ip4)
+        gre_if.add_vpp_config()
+        gre_if.admin_up()
+        gre_if.config_ip4()
+
+        # bring the session up now the routes are present
+        self.vpp_session = VppBFDUDPSession(self,
+                                            gre_if,
+                                            gre_if.remote_ip4,
+                                            is_tunnel=True)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+
+        self.test_session = BFDTestSession(
+            self, gre_if, AF_INET,
+            tunnel_header=(IP(src=self.pg0.remote_ip4,
+                              dst=self.pg0.local_ip4) /
+                           GRE()),
+            phy_interface=self.pg0)
+
+        # packets to match against both of the routes
+        p = [(Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+              IP(src=self.pg0.remote_ip4, dst=gre_if.remote_ip4) /
+              UDP(sport=1234, dport=1234) /
+              Raw(b'\xa5' * 100))]
+
+        # session is up - traffic passes
+        bfd_session_up(self)
+
+        self.send_and_expect(self.pg0, p, self.pg0)
+
+        # bring session down
+        bfd_session_down(self)
+
+
+class BFDSHA1TestCase(VppTestCase):
+    """Bidirectional Forwarding Detection (BFD) (SHA1 auth) """
+
+    pg0 = None
+    vpp_clock_offset = None
+    vpp_session = None
+    test_session = None
+
+    @classmethod
+    def force_solo(cls):
+        return True
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFDSHA1TestCase, cls).setUpClass()
+        cls.vapi.cli("set log class bfd level debug")
+        try:
+            cls.create_pg_interfaces([0])
+            cls.pg0.config_ip4()
+            cls.pg0.admin_up()
+            cls.pg0.resolve_arp()
+
+        except Exception:
+            super(BFDSHA1TestCase, cls).tearDownClass()
+            raise
+
+    @classmethod
+    def tearDownClass(cls):
+        super(BFDSHA1TestCase, cls).tearDownClass()
+
+    def setUp(self):
+        super(BFDSHA1TestCase, self).setUp()
+        self.factory = AuthKeyFactory()
+        self.vapi.want_bfd_events()
+        self.pg0.enable_capture()
+
+    def tearDown(self):
+        if not self.vpp_dead:
+            self.vapi.want_bfd_events(enable_disable=False)
+        self.vapi.collect_events()  # clear the event queue
+        super(BFDSHA1TestCase, self).tearDown()
+
+    def test_session_up(self):
+        """ bring BFD session up """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4,
+                                            sha1_key=key)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        bfd_session_up(self)
+
+    def test_hold_up(self):
+        """ hold BFD session up """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4,
+                                            sha1_key=key)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            wait_for_bfd_packet(self)
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+
+    def test_hold_up_meticulous(self):
+        """ hold BFD session up - meticulous auth """
+        key = self.factory.create_random_key(
+            self, BFDAuthType.meticulous_keyed_sha1)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        # specify sequence number so that it wraps
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id,
+            our_seq_number=0xFFFFFFFF - 4)
+        bfd_session_up(self)
+        for dummy in range(30):
+            wait_for_bfd_packet(self)
+            self.test_session.inc_seq_num()
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+
+    def test_send_bad_seq_number(self):
+        """ session is not kept alive by msgs with bad sequence numbers"""
+        key = self.factory.create_random_key(
+            self, BFDAuthType.meticulous_keyed_sha1)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session.add_vpp_config()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        bfd_session_up(self)
+        detection_time = self.test_session.detect_mult *\
+            self.vpp_session.required_min_rx / USEC_IN_SEC
+        send_until = time.time() + 2 * detection_time
+        while time.time() < send_until:
+            self.test_session.send_packet()
+            self.sleep(0.7 * self.vpp_session.required_min_rx / USEC_IN_SEC,
+                       "time between bfd packets")
+        e = self.vapi.collect_events()
+        # session should be down now, because the sequence numbers weren't
+        # updated
+        self.assert_equal(len(e), 1, "number of bfd events")
+        verify_event(self, e[0], expected_state=BFDState.down)
+
+    def execute_rogue_session_scenario(self, vpp_bfd_udp_session,
+                                       legitimate_test_session,
+                                       rogue_test_session,
+                                       rogue_bfd_values=None):
+        """ execute a rogue session interaction scenario
+
+        1. create vpp session, add config
+        2. bring the legitimate session up
+        3. copy the bfd values from legitimate session to rogue session
+        4. apply rogue_bfd_values to rogue session
+        5. set rogue session state to down
+        6. send message to take the session down from the rogue session
+        7. assert that the legitimate session is unaffected
+        """
+
+        self.vpp_session = vpp_bfd_udp_session
+        self.vpp_session.add_vpp_config()
+        self.test_session = legitimate_test_session
+        # bring vpp session up
+        bfd_session_up(self)
+        # send packet from rogue session
+        rogue_test_session.update(
+            my_discriminator=self.test_session.my_discriminator,
+            your_discriminator=self.test_session.your_discriminator,
+            desired_min_tx=self.test_session.desired_min_tx,
+            required_min_rx=self.test_session.required_min_rx,
+            detect_mult=self.test_session.detect_mult,
+            diag=self.test_session.diag,
+            state=self.test_session.state,
+            auth_type=self.test_session.auth_type)
+        if rogue_bfd_values:
+            rogue_test_session.update(**rogue_bfd_values)
+        rogue_test_session.update(state=BFDState.down)
+        rogue_test_session.send_packet()
+        wait_for_bfd_packet(self)
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+
+    def test_mismatch_auth(self):
+        """ session is not brought down by unauthenticated msg """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key)
+        legitimate_test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=vpp_session.bfd_key_id)
+        rogue_test_session = BFDTestSession(self, self.pg0, AF_INET)
+        self.execute_rogue_session_scenario(vpp_session,
+                                            legitimate_test_session,
+                                            rogue_test_session)
+
+    def test_mismatch_bfd_key_id(self):
+        """ session is not brought down by msg with non-existent key-id """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key)
+        # pick a different random bfd key id
+        x = randint(0, 255)
+        while x == vpp_session.bfd_key_id:
+            x = randint(0, 255)
+        legitimate_test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=vpp_session.bfd_key_id)
+        rogue_test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key, bfd_key_id=x)
+        self.execute_rogue_session_scenario(vpp_session,
+                                            legitimate_test_session,
+                                            rogue_test_session)
+
+    def test_mismatched_auth_type(self):
+        """ session is not brought down by msg with wrong auth type """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key)
+        legitimate_test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=vpp_session.bfd_key_id)
+        rogue_test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=vpp_session.bfd_key_id)
+        self.execute_rogue_session_scenario(
+            vpp_session, legitimate_test_session, rogue_test_session,
+            {'auth_type': BFDAuthType.keyed_md5})
+
+    def test_restart(self):
+        """ simulate remote peer restart and resynchronization """
+        key = self.factory.create_random_key(
+            self, BFDAuthType.meticulous_keyed_sha1)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session.add_vpp_config()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id, our_seq_number=0)
+        bfd_session_up(self)
+        # don't send any packets for 2*detection_time
+        detection_time = self.test_session.detect_mult *\
+            self.vpp_session.required_min_rx / USEC_IN_SEC
+        self.sleep(2 * detection_time, "simulating peer restart")
+        events = self.vapi.collect_events()
+        self.assert_equal(len(events), 1, "number of bfd events")
+        verify_event(self, events[0], expected_state=BFDState.down)
+        self.test_session.update(state=BFDState.down)
+        # reset sequence number
+        self.test_session.our_seq_number = 0
+        self.test_session.vpp_seq_number = None
+        # now throw away any pending packets
+        self.pg0.enable_capture()
+        self.test_session.my_discriminator = 0
+        bfd_session_up(self)
+
+
+class BFDAuthOnOffTestCase(VppTestCase):
+    """Bidirectional Forwarding Detection (BFD) (changing auth) """
+
+    pg0 = None
+    vpp_session = None
+    test_session = None
+
+    @classmethod
+    def force_solo(cls):
+        return True
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFDAuthOnOffTestCase, cls).setUpClass()
+        cls.vapi.cli("set log class bfd level debug")
+        try:
+            cls.create_pg_interfaces([0])
+            cls.pg0.config_ip4()
+            cls.pg0.admin_up()
+            cls.pg0.resolve_arp()
+
+        except Exception:
+            super(BFDAuthOnOffTestCase, cls).tearDownClass()
+            raise
+
+    @classmethod
+    def tearDownClass(cls):
+        super(BFDAuthOnOffTestCase, cls).tearDownClass()
+
+    def setUp(self):
+        super(BFDAuthOnOffTestCase, self).setUp()
+        self.factory = AuthKeyFactory()
+        self.vapi.want_bfd_events()
+        self.pg0.enable_capture()
+
+    def tearDown(self):
+        if not self.vpp_dead:
+            self.vapi.want_bfd_events(enable_disable=False)
+        self.vapi.collect_events()  # clear the event queue
+        super(BFDAuthOnOffTestCase, self).tearDown()
+
+    def test_auth_on_immediate(self):
+        """ turn auth on without disturbing session state (immediate) """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4)
+        self.vpp_session.add_vpp_config()
+        self.test_session = BFDTestSession(self, self.pg0, AF_INET)
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.send_packet()
+        self.vpp_session.activate_auth(key)
+        self.test_session.bfd_key_id = self.vpp_session.bfd_key_id
+        self.test_session.sha1_key = key
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+
+    def test_auth_off_immediate(self):
+        """ turn auth off without disturbing session state (immediate) """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session.add_vpp_config()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        bfd_session_up(self)
+        # self.vapi.want_bfd_events(enable_disable=0)
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.inc_seq_num()
+            self.test_session.send_packet()
+        self.vpp_session.deactivate_auth()
+        self.test_session.bfd_key_id = None
+        self.test_session.sha1_key = None
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.inc_seq_num()
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+
+    def test_auth_change_key_immediate(self):
+        """ change auth key without disturbing session state (immediate) """
+        key1 = self.factory.create_random_key(self)
+        key1.add_vpp_config()
+        key2 = self.factory.create_random_key(self)
+        key2.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4, sha1_key=key1)
+        self.vpp_session.add_vpp_config()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key1,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.send_packet()
+        self.vpp_session.activate_auth(key2)
+        self.test_session.bfd_key_id = self.vpp_session.bfd_key_id
+        self.test_session.sha1_key = key2
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+
+    def test_auth_on_delayed(self):
+        """ turn auth on without disturbing session state (delayed) """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4)
+        self.vpp_session.add_vpp_config()
+        self.test_session = BFDTestSession(self, self.pg0, AF_INET)
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            wait_for_bfd_packet(self)
+            self.test_session.send_packet()
+        self.vpp_session.activate_auth(key, delayed=True)
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.send_packet()
+        self.test_session.bfd_key_id = self.vpp_session.bfd_key_id
+        self.test_session.sha1_key = key
+        self.test_session.send_packet()
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+
+    def test_auth_off_delayed(self):
+        """ turn auth off without disturbing session state (delayed) """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4, sha1_key=key)
+        self.vpp_session.add_vpp_config()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.send_packet()
+        self.vpp_session.deactivate_auth(delayed=True)
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.send_packet()
+        self.test_session.bfd_key_id = None
+        self.test_session.sha1_key = None
+        self.test_session.send_packet()
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+
+    def test_auth_change_key_delayed(self):
+        """ change auth key without disturbing session state (delayed) """
+        key1 = self.factory.create_random_key(self)
+        key1.add_vpp_config()
+        key2 = self.factory.create_random_key(self)
+        key2.add_vpp_config()
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip4, sha1_key=key1)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = BFDTestSession(
+            self, self.pg0, AF_INET, sha1_key=key1,
+            bfd_key_id=self.vpp_session.bfd_key_id)
+        bfd_session_up(self)
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.send_packet()
+        self.vpp_session.activate_auth(key2, delayed=True)
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.send_packet()
+        self.test_session.bfd_key_id = self.vpp_session.bfd_key_id
+        self.test_session.sha1_key = key2
+        self.test_session.send_packet()
+        for dummy in range(self.test_session.detect_mult * 2):
+            p = wait_for_bfd_packet(self)
+            self.assert_equal(p[BFD].state, BFDState.up, BFDState)
+            self.test_session.send_packet()
+        self.assert_equal(self.vpp_session.state, BFDState.up, BFDState)
+        self.assert_equal(len(self.vapi.collect_events()), 0,
+                          "number of bfd events")
+
+
+class BFDCLITestCase(VppTestCase):
+    """Bidirectional Forwarding Detection (BFD) (CLI) """
+    pg0 = None
+
+    @classmethod
+    def force_solo(cls):
+        return True
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFDCLITestCase, cls).setUpClass()
+        cls.vapi.cli("set log class bfd level debug")
+        try:
+            cls.create_pg_interfaces((0,))
+            cls.pg0.config_ip4()
+            cls.pg0.config_ip6()
+            cls.pg0.resolve_arp()
+            cls.pg0.resolve_ndp()
+
+        except Exception:
+            super(BFDCLITestCase, cls).tearDownClass()
+            raise
+
+    @classmethod
+    def tearDownClass(cls):
+        super(BFDCLITestCase, cls).tearDownClass()
+
+    def setUp(self):
+        super(BFDCLITestCase, self).setUp()
+        self.factory = AuthKeyFactory()
+        self.pg0.enable_capture()
+
+    def tearDown(self):
+        try:
+            self.vapi.want_bfd_events(enable_disable=False)
+        except UnexpectedApiReturnValueError:
+            # some tests aren't subscribed, so this is not an issue
+            pass
+        self.vapi.collect_events()  # clear the event queue
+        super(BFDCLITestCase, self).tearDown()
+
+    def cli_verify_no_response(self, cli):
+        """ execute a CLI, asserting that the response is empty """
+        self.assert_equal(self.vapi.cli(cli),
+                          "",
+                          "CLI command response")
+
+    def cli_verify_response(self, cli, expected):
+        """ execute a CLI, asserting that the response matches expectation """
+        try:
+            reply = self.vapi.cli(cli)
+        except CliFailedCommandError as cli_error:
+            reply = str(cli_error)
+        self.assert_equal(reply.strip(),
+                          expected,
+                          "CLI command response")
+
+    def test_show(self):
+        """ show commands """
+        k1 = self.factory.create_random_key(self)
+        k1.add_vpp_config()
+        k2 = self.factory.create_random_key(
+            self, auth_type=BFDAuthType.meticulous_keyed_sha1)
+        k2.add_vpp_config()
+        s1 = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        s1.add_vpp_config()
+        s2 = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip6, af=AF_INET6,
+                              sha1_key=k2)
+        s2.add_vpp_config()
+        self.logger.info(self.vapi.ppcli("show bfd keys"))
+        self.logger.info(self.vapi.ppcli("show bfd sessions"))
+        self.logger.info(self.vapi.ppcli("show bfd"))
+
+    def test_set_del_sha1_key(self):
+        """ set/delete SHA1 auth key """
+        k = self.factory.create_random_key(self)
+        self.registry.register(k, self.logger)
+        self.cli_verify_no_response(
+            "bfd key set conf-key-id %s type keyed-sha1 secret %s" %
+            (k.conf_key_id,
+                "".join("{:02x}".format(scapy.compat.orb(c)) for c in k.key)))
+        self.assertTrue(k.query_vpp_config())
+        self.vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=k)
+        self.vpp_session.add_vpp_config()
+        self.test_session = \
+            BFDTestSession(self, self.pg0, AF_INET, sha1_key=k,
+                           bfd_key_id=self.vpp_session.bfd_key_id)
+        self.vapi.want_bfd_events()
+        bfd_session_up(self)
+        bfd_session_down(self)
+        # try to replace the secret for the key - should fail because the key
+        # is in-use
+        k2 = self.factory.create_random_key(self)
+        self.cli_verify_response(
+            "bfd key set conf-key-id %s type keyed-sha1 secret %s" %
+            (k.conf_key_id,
+                "".join("{:02x}".format(scapy.compat.orb(c)) for c in k2.key)),
+            "bfd key set: `bfd_auth_set_key' API call failed, "
+            "rv=-103:BFD object in use")
+        # manipulating the session using old secret should still work
+        bfd_session_up(self)
+        bfd_session_down(self)
+        self.vpp_session.remove_vpp_config()
+        self.cli_verify_no_response(
+            "bfd key del conf-key-id %s" % k.conf_key_id)
+        self.assertFalse(k.query_vpp_config())
+
+    def test_set_del_meticulous_sha1_key(self):
+        """ set/delete meticulous SHA1 auth key """
+        k = self.factory.create_random_key(
+            self, auth_type=BFDAuthType.meticulous_keyed_sha1)
+        self.registry.register(k, self.logger)
+        self.cli_verify_no_response(
+            "bfd key set conf-key-id %s type meticulous-keyed-sha1 secret %s" %
+            (k.conf_key_id,
+                "".join("{:02x}".format(scapy.compat.orb(c)) for c in k.key)))
+        self.assertTrue(k.query_vpp_config())
+        self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                            self.pg0.remote_ip6, af=AF_INET6,
+                                            sha1_key=k)
+        self.vpp_session.add_vpp_config()
+        self.vpp_session.admin_up()
+        self.test_session = \
+            BFDTestSession(self, self.pg0, AF_INET6, sha1_key=k,
+                           bfd_key_id=self.vpp_session.bfd_key_id)
+        self.vapi.want_bfd_events()
+        bfd_session_up(self)
+        bfd_session_down(self)
+        # try to replace the secret for the key - should fail because the key
+        # is in-use
+        k2 = self.factory.create_random_key(self)
+        self.cli_verify_response(
+            "bfd key set conf-key-id %s type keyed-sha1 secret %s" %
+            (k.conf_key_id,
+                "".join("{:02x}".format(scapy.compat.orb(c)) for c in k2.key)),
+            "bfd key set: `bfd_auth_set_key' API call failed, "
+            "rv=-103:BFD object in use")
+        # manipulating the session using old secret should still work
+        bfd_session_up(self)
+        bfd_session_down(self)
+        self.vpp_session.remove_vpp_config()
+        self.cli_verify_no_response(
+            "bfd key del conf-key-id %s" % k.conf_key_id)
+        self.assertFalse(k.query_vpp_config())
+
+    def test_add_mod_del_bfd_udp(self):
+        """ create/modify/delete IPv4 BFD UDP session """
+        vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4)
+        self.registry.register(vpp_session, self.logger)
+        cli_add_cmd = "bfd udp session add interface %s local-addr %s " \
+            "peer-addr %s desired-min-tx %s required-min-rx %s "\
+            "detect-mult %s" % (self.pg0.name, self.pg0.local_ip4,
+                                self.pg0.remote_ip4,
+                                vpp_session.desired_min_tx,
+                                vpp_session.required_min_rx,
+                                vpp_session.detect_mult)
+        self.cli_verify_no_response(cli_add_cmd)
+        # 2nd add should fail
+        self.cli_verify_response(
+            cli_add_cmd,
+            "bfd udp session add: `bfd_add_add_session' API call"
+            " failed, rv=-101:Duplicate BFD object")
+        verify_bfd_session_config(self, vpp_session)
+        mod_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4,
+            required_min_rx=2 * vpp_session.required_min_rx,
+            desired_min_tx=3 * vpp_session.desired_min_tx,
+            detect_mult=4 * vpp_session.detect_mult)
+        self.cli_verify_no_response(
+            "bfd udp session mod interface %s local-addr %s peer-addr %s "
+            "desired-min-tx %s required-min-rx %s detect-mult %s" %
+            (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4,
+             mod_session.desired_min_tx, mod_session.required_min_rx,
+             mod_session.detect_mult))
+        verify_bfd_session_config(self, mod_session)
+        cli_del_cmd = "bfd udp session del interface %s local-addr %s "\
+            "peer-addr %s" % (self.pg0.name,
+                              self.pg0.local_ip4, self.pg0.remote_ip4)
+        self.cli_verify_no_response(cli_del_cmd)
+        # 2nd del is expected to fail
+        self.cli_verify_response(
+            cli_del_cmd, "bfd udp session del: `bfd_udp_del_session' API call"
+            " failed, rv=-102:No such BFD object")
+        self.assertFalse(vpp_session.query_vpp_config())
+
+    def test_add_mod_del_bfd_udp6(self):
+        """ create/modify/delete IPv6 BFD UDP session """
+        vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip6, af=AF_INET6)
+        self.registry.register(vpp_session, self.logger)
+        cli_add_cmd = "bfd udp session add interface %s local-addr %s " \
+            "peer-addr %s desired-min-tx %s required-min-rx %s "\
+            "detect-mult %s" % (self.pg0.name, self.pg0.local_ip6,
+                                self.pg0.remote_ip6,
+                                vpp_session.desired_min_tx,
+                                vpp_session.required_min_rx,
+                                vpp_session.detect_mult)
+        self.cli_verify_no_response(cli_add_cmd)
+        # 2nd add should fail
+        self.cli_verify_response(
+            cli_add_cmd,
+            "bfd udp session add: `bfd_add_add_session' API call"
+            " failed, rv=-101:Duplicate BFD object")
+        verify_bfd_session_config(self, vpp_session)
+        mod_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip6, af=AF_INET6,
+            required_min_rx=2 * vpp_session.required_min_rx,
+            desired_min_tx=3 * vpp_session.desired_min_tx,
+            detect_mult=4 * vpp_session.detect_mult)
+        self.cli_verify_no_response(
+            "bfd udp session mod interface %s local-addr %s peer-addr %s "
+            "desired-min-tx %s required-min-rx %s detect-mult %s" %
+            (self.pg0.name, self.pg0.local_ip6, self.pg0.remote_ip6,
+             mod_session.desired_min_tx,
+             mod_session.required_min_rx, mod_session.detect_mult))
+        verify_bfd_session_config(self, mod_session)
+        cli_del_cmd = "bfd udp session del interface %s local-addr %s "\
+            "peer-addr %s" % (self.pg0.name,
+                              self.pg0.local_ip6, self.pg0.remote_ip6)
+        self.cli_verify_no_response(cli_del_cmd)
+        # 2nd del is expected to fail
+        self.cli_verify_response(
+            cli_del_cmd,
+            "bfd udp session del: `bfd_udp_del_session' API call"
+            " failed, rv=-102:No such BFD object")
+        self.assertFalse(vpp_session.query_vpp_config())
+
+    def test_add_mod_del_bfd_udp_auth(self):
+        """ create/modify/delete IPv4 BFD UDP session (authenticated) """
+        key = self.factory.create_random_key(self)
+        key.add_vpp_config()
+        vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key)
+        self.registry.register(vpp_session, self.logger)
+        cli_add_cmd = "bfd udp session add interface %s local-addr %s " \
+            "peer-addr %s desired-min-tx %s required-min-rx %s "\
+            "detect-mult %s conf-key-id %s bfd-key-id %s"\
+            % (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4,
+               vpp_session.desired_min_tx, vpp_session.required_min_rx,
+               vpp_session.detect_mult, key.conf_key_id,
+               vpp_session.bfd_key_id)
+        self.cli_verify_no_response(cli_add_cmd)
+        # 2nd add should fail
+        self.cli_verify_response(
+            cli_add_cmd,
+            "bfd udp session add: `bfd_add_add_session' API call"
+            " failed, rv=-101:Duplicate BFD object")
+        verify_bfd_session_config(self, vpp_session)
+        mod_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip4, sha1_key=key,
+            bfd_key_id=vpp_session.bfd_key_id,
+            required_min_rx=2 * vpp_session.required_min_rx,
+            desired_min_tx=3 * vpp_session.desired_min_tx,
+            detect_mult=4 * vpp_session.detect_mult)
+        self.cli_verify_no_response(
+            "bfd udp session mod interface %s local-addr %s peer-addr %s "
+            "desired-min-tx %s required-min-rx %s detect-mult %s" %
+            (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4,
+             mod_session.desired_min_tx,
+             mod_session.required_min_rx, mod_session.detect_mult))
+        verify_bfd_session_config(self, mod_session)
+        cli_del_cmd = "bfd udp session del interface %s local-addr %s "\
+            "peer-addr %s" % (self.pg0.name,
+                              self.pg0.local_ip4, self.pg0.remote_ip4)
+        self.cli_verify_no_response(cli_del_cmd)
+        # 2nd del is expected to fail
+        self.cli_verify_response(
+            cli_del_cmd,
+            "bfd udp session del: `bfd_udp_del_session' API call"
+            " failed, rv=-102:No such BFD object")
+        self.assertFalse(vpp_session.query_vpp_config())
+
+    def test_add_mod_del_bfd_udp6_auth(self):
+        """ create/modify/delete IPv6 BFD UDP session (authenticated) """
+        key = self.factory.create_random_key(
+            self, auth_type=BFDAuthType.meticulous_keyed_sha1)
+        key.add_vpp_config()
+        vpp_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip6, af=AF_INET6, sha1_key=key)
+        self.registry.register(vpp_session, self.logger)
+        cli_add_cmd = "bfd udp session add interface %s local-addr %s " \
+            "peer-addr %s desired-min-tx %s required-min-rx %s "\
+            "detect-mult %s conf-key-id %s bfd-key-id %s" \
+            % (self.pg0.name, self.pg0.local_ip6, self.pg0.remote_ip6,
+               vpp_session.desired_min_tx, vpp_session.required_min_rx,
+               vpp_session.detect_mult, key.conf_key_id,
+               vpp_session.bfd_key_id)
+        self.cli_verify_no_response(cli_add_cmd)
+        # 2nd add should fail
+        self.cli_verify_response(
+            cli_add_cmd,
+            "bfd udp session add: `bfd_add_add_session' API call"
+            " failed, rv=-101:Duplicate BFD object")
+        verify_bfd_session_config(self, vpp_session)
+        mod_session = VppBFDUDPSession(
+            self, self.pg0, self.pg0.remote_ip6, af=AF_INET6, sha1_key=key,
+            bfd_key_id=vpp_session.bfd_key_id,
+            required_min_rx=2 * vpp_session.required_min_rx,
+            desired_min_tx=3 * vpp_session.desired_min_tx,
+            detect_mult=4 * vpp_session.detect_mult)
+        self.cli_verify_no_response(
+            "bfd udp session mod interface %s local-addr %s peer-addr %s "
+            "desired-min-tx %s required-min-rx %s detect-mult %s" %
+            (self.pg0.name, self.pg0.local_ip6, self.pg0.remote_ip6,
+             mod_session.desired_min_tx,
+             mod_session.required_min_rx, mod_session.detect_mult))
+        verify_bfd_session_config(self, mod_session)
+        cli_del_cmd = "bfd udp session del interface %s local-addr %s "\
+            "peer-addr %s" % (self.pg0.name,
+                              self.pg0.local_ip6, self.pg0.remote_ip6)
+        self.cli_verify_no_response(cli_del_cmd)
+        # 2nd del is expected to fail
+        self.cli_verify_response(
+            cli_del_cmd,
+            "bfd udp session del: `bfd_udp_del_session' API call"
+            " failed, rv=-102:No such BFD object")
+        self.assertFalse(vpp_session.query_vpp_config())
+
+    def test_auth_on_off(self):
+        """ turn authentication on and off """
+        key = self.factory.create_random_key(
+            self, auth_type=BFDAuthType.meticulous_keyed_sha1)
+        key.add_vpp_config()
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        auth_session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
+                                        sha1_key=key)
+        session.add_vpp_config()
+        cli_activate = \
+            "bfd udp session auth activate interface %s local-addr %s "\
+            "peer-addr %s conf-key-id %s bfd-key-id %s"\
+            % (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4,
+               key.conf_key_id, auth_session.bfd_key_id)
+        self.cli_verify_no_response(cli_activate)
+        verify_bfd_session_config(self, auth_session)
+        self.cli_verify_no_response(cli_activate)
+        verify_bfd_session_config(self, auth_session)
+        cli_deactivate = \
+            "bfd udp session auth deactivate interface %s local-addr %s "\
+            "peer-addr %s "\
+            % (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4)
+        self.cli_verify_no_response(cli_deactivate)
+        verify_bfd_session_config(self, session)
+        self.cli_verify_no_response(cli_deactivate)
+        verify_bfd_session_config(self, session)
+
+    def test_auth_on_off_delayed(self):
+        """ turn authentication on and off (delayed) """
+        key = self.factory.create_random_key(
+            self, auth_type=BFDAuthType.meticulous_keyed_sha1)
+        key.add_vpp_config()
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        auth_session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4,
+                                        sha1_key=key)
+        session.add_vpp_config()
+        cli_activate = \
+            "bfd udp session auth activate interface %s local-addr %s "\
+            "peer-addr %s conf-key-id %s bfd-key-id %s delayed yes"\
+            % (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4,
+               key.conf_key_id, auth_session.bfd_key_id)
+        self.cli_verify_no_response(cli_activate)
+        verify_bfd_session_config(self, auth_session)
+        self.cli_verify_no_response(cli_activate)
+        verify_bfd_session_config(self, auth_session)
+        cli_deactivate = \
+            "bfd udp session auth deactivate interface %s local-addr %s "\
+            "peer-addr %s delayed yes"\
+            % (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4)
+        self.cli_verify_no_response(cli_deactivate)
+        verify_bfd_session_config(self, session)
+        self.cli_verify_no_response(cli_deactivate)
+        verify_bfd_session_config(self, session)
+
+    def test_admin_up_down(self):
+        """ put session admin-up and admin-down """
+        session = VppBFDUDPSession(self, self.pg0, self.pg0.remote_ip4)
+        session.add_vpp_config()
+        cli_down = \
+            "bfd udp session set-flags admin down interface %s local-addr %s "\
+            "peer-addr %s "\
+            % (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4)
+        cli_up = \
+            "bfd udp session set-flags admin up interface %s local-addr %s "\
+            "peer-addr %s "\
+            % (self.pg0.name, self.pg0.local_ip4, self.pg0.remote_ip4)
+        self.cli_verify_no_response(cli_down)
+        verify_bfd_session_config(self, session, state=BFDState.admin_down)
+        self.cli_verify_no_response(cli_up)
+        verify_bfd_session_config(self, session, state=BFDState.down)
+
+    def test_set_del_udp_echo_source(self):
+        """ set/del udp echo source """
+        self.create_loopback_interfaces(1)
+        self.loopback0 = self.lo_interfaces[0]
+        self.loopback0.admin_up()
+        self.cli_verify_response("show bfd echo-source",
+                                 "UDP echo source is not set.")
+        cli_set = "bfd udp echo-source set interface %s" % self.loopback0.name
+        self.cli_verify_no_response(cli_set)
+        self.cli_verify_response("show bfd echo-source",
+                                 "UDP echo source is: %s\n"
+                                 "IPv4 address usable as echo source: none\n"
+                                 "IPv6 address usable as echo source: none" %
+                                 self.loopback0.name)
+        self.loopback0.config_ip4()
+        echo_ip4 = str(ipaddress.IPv4Address(int(ipaddress.IPv4Address(
+            self.loopback0.local_ip4)) ^ 1))
+        self.cli_verify_response("show bfd echo-source",
+                                 "UDP echo source is: %s\n"
+                                 "IPv4 address usable as echo source: %s\n"
+                                 "IPv6 address usable as echo source: none" %
+                                 (self.loopback0.name, echo_ip4))
+        echo_ip6 = str(ipaddress.IPv6Address(int(ipaddress.IPv6Address(
+            self.loopback0.local_ip6)) ^ 1))
+        self.loopback0.config_ip6()
+        self.cli_verify_response("show bfd echo-source",
+                                 "UDP echo source is: %s\n"
+                                 "IPv4 address usable as echo source: %s\n"
+                                 "IPv6 address usable as echo source: %s" %
+                                 (self.loopback0.name, echo_ip4, echo_ip6))
+        cli_del = "bfd udp echo-source del"
+        self.cli_verify_no_response(cli_del)
+        self.cli_verify_response("show bfd echo-source",
+                                 "UDP echo source is not set.")
+
+
+if __name__ == '__main__':
+    unittest.main(testRunner=VppTestRunner)