Initial commit of Sphinx docs

Change-Id: I9fca8fb98502dffc2555f9de7f507b6f006e0e77
Signed-off-by: John DeNisco <jdenisco@cisco.com>

2 files changed, 1350 insertions, 0 deletions

diff --git a/docs/guides/progressivevpp/index.rst b/docs/guides/progressivevpp/index.rst
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+.. _progressivevpp:
+
+=========================================
+Progressive VPP Tutorial
+=========================================
+
+.. toctree::
+
+    vagrant
\ No newline at end of file
diff --git a/docs/guides/progressivevpp/vagrant.rst b/docs/guides/progressivevpp/vagrant.rst
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+.. _vagrant:
+
+.. toctree::
+
+.. _introduction-to-vpp-vagrant:
+
+Introduction
+---------------
+
+This tutorial is designed for you to be able to run it on a single Ubuntu 16.04 VM on your laptop.
+It walks you through some very basic vpp senarios, with a focus on learning vpp commands, doing common actions,
+and being able to discover common things about the state of a running vpp.
+
+This is *not* intended to be a 'how to run in a production environment' set of instructions.
+
+Exercise: Setting up your environment
+-------------------------------------
+
+All of these exercises are designed to be performed on an Ubuntu 16.04 (Xenial) box.
+
+If you have an Ubuntu 16.04 box on which you have sudo, you can feel free to use that.
+
+If you do not, a Vagrantfile is provided to setup a basic Ubuntu 16.04 box for you
+
+.. _vagrant-set-up:
+
+Vagrant Set Up
+--------------
+
+Action: Install Virtualbox
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If you do not already have virtualbox on your laptop (or if it is not up to date), please download and install it:
+
+https://www.virtualbox.org/wiki/Downloads
+
+Action: Install Vagrant
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If you do not already have Vagrant on your laptop (or if it is not up to date), please download it:
+
+https://www.vagrantup.com/downloads.html
+
+Action: Create a Vagrant Directory
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Create a directory on your laptop
+
+.. code-block:: console
+
+    mkdir fdio-tutorial
+    cd fdio-tutorial/
+
+.. _create-vagrant-file:
+
+Create a Vagrantfile
+^^^^^^^^^^^^^^^^^^^^
+
+.. code-block:: console
+
+    # -*- mode: ruby -*-
+    # vi: set ft=ruby :
+
+    Vagrant.configure(2) do |config|
+
+    config.vm.box = "puppetlabs/ubuntu-16.04-64-nocm"
+    config.vm.box_check_update = false
+
+    vmcpu=(ENV['VPP_VAGRANT_VMCPU'] || 2)
+    vmram=(ENV['VPP_VAGRANT_VMRAM'] || 4096)
+
+    config.ssh.forward_agent = true
+
+    config.vm.provider "virtualbox" do |vb|
+        vb.customize ["modifyvm", :id, "--ioapic", "on"]
+        vb.memory = "#{vmram}"
+        vb.cpus = "#{vmcpu}"
+        #support for the SSE4.x instruction is required in some versions of VB.
+        vb.customize ["setextradata", :id, "VBoxInternal/CPUM/SSE4.1", "1"]
+        vb.customize ["setextradata", :id, "VBoxInternal/CPUM/SSE4.2", "1"]
+    end
+    end
+
+Action: Vagrant Up
+^^^^^^^^^^^^^^^^^^
+
+Bring up your Vagrant VM:
+
+.. code-block:: console
+
+    vagrant up
+
+
+Action: ssh to Vagrant VM
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. code-block:: console
+
+    vagrant ssh
+
+Exercise: Install VPP
+---------------------
+**Skills to be Learned**
+
+    * Learn how to install vpp binary packges using apt-get.
+
+Follow the instructions at :ref:`Installing VPP Binaries <install_vpp>` for installing xenial vpp packages from the release repo.  Please note, certain aspects of this tutorial require vpp 17.10 or later.
+
+Exercise: VPP basics
+---------------------
+**Skills to be Learned**
+
+By the end of the exercise you should be able to:
+
+* Run a vpp instance in a mode which allows multiple vpp processes to run
+* Issue vpp commands from the unix shell
+* Run a vpp shell and issue it commands
+
+
+VPP command learned in this exercise
+--------------------------------------
+
+* `show ver <https://docs.fd.io/vpp/17.04/clicmd_src_vpp_app.html#clicmd_show_version>`_
+
+Action: Remove dpdk plugin 
+--------------------------
+In this tutorial, we will be running multiple vpp instances.  DPDK does not work well with multiple instances, and so to run multiple instances we will need to disable the dpdk-plugin by removing it:
+
+.. code-block:: console
+    
+    sudo rm -rf /usr/lib/vpp_plugins/dpdk_plugin.so
+
+..how-to-run-vpp:
+
+Action: Run VPP
+-----------------
+
+VPP runs in userspace.  In a production environment you will often run it with DPDK to connect to real NICs or vhost to connect to VMs.
+In those circumstances you usually run a single instance of vpp.
+
+For purposes of this tutorial, it is going to be extremely useful to run multiple instances of vpp, and connect them to each other to form
+a topology.  Fortunately, vpp supports this.
+
+When running multiple vpp instances, each instance needs to have specified a 'name' or 'prefix'.  In the example below, the 'name' or 'prefix' is "vpp1". Note that only one instance can use the dpdk plugin, since this plugin is trying to acquire a lock on a file.
+
+.. code-block:: console
+   
+    sudo vpp unix {cli-listen /run/vpp/cli-vpp1.sock} api-segment { prefix vpp1 }
+
+**Example Output:**
+
+.. code-block:: console
+   
+    vlib_plugin_early_init:230: plugin path /usr/lib/vpp_plugins
+
+Please note:
+
+* "api-segment {prefix vpp1}" tells vpp how to name the files in /dev/shm/ for your vpp instance differently from the default.  
+* "unix {cli-listen /run/vpp/cli-vpp1.sock}" tells vpp to use a non-default socket file when being addressed by vppctl.
+
+If you can't see the vpp process running on the host, activate the nodaemon option to better understand what is happening
+
+.. code-block:: console
+    
+    sudo vpp unix {nodaemon cli-listen /run/vpp/cli-vpp1.sock} api-segment { prefix vpp1 }
+
+**Example Output with errors from the dpdk plugin:**
+
+.. code-block:: console
+
+    vlib_plugin_early_init:356: plugin path /usr/lib/vpp_plugins
+    load_one_plugin:184: Loaded plugin: acl_plugin.so (Access Control Lists)
+    load_one_plugin:184: Loaded plugin: dpdk_plugin.so (Data Plane Development Kit (DPDK))
+    load_one_plugin:184: Loaded plugin: flowprobe_plugin.so (Flow per Packet)
+    load_one_plugin:184: Loaded plugin: gtpu_plugin.so (GTPv1-U)
+    load_one_plugin:184: Loaded plugin: ila_plugin.so (Identifier-locator addressing for IPv6)
+    load_one_plugin:184: Loaded plugin: ioam_plugin.so (Inbound OAM)
+    load_one_plugin:114: Plugin disabled (default): ixge_plugin.so
+    load_one_plugin:184: Loaded plugin: kubeproxy_plugin.so (kube-proxy data plane)
+    load_one_plugin:184: Loaded plugin: l2e_plugin.so (L2 Emulation)
+    load_one_plugin:184: Loaded plugin: lb_plugin.so (Load Balancer)
+    load_one_plugin:184: Loaded plugin: libsixrd_plugin.so (IPv6 Rapid Deployment on IPv4 Infrastructure (RFC5969))
+    load_one_plugin:184: Loaded plugin: memif_plugin.so (Packet Memory Interface (experimetal))
+    load_one_plugin:184: Loaded plugin: nat_plugin.so (Network Address Translation)
+    load_one_plugin:184: Loaded plugin: pppoe_plugin.so (PPPoE)
+    load_one_plugin:184: Loaded plugin: stn_plugin.so (VPP Steals the NIC for Container integration)
+    vpp[10211]: vlib_pci_bind_to_uio: Skipping PCI device 0000:00:03.0 as host interface eth0 is up
+    vpp[10211]: vlib_pci_bind_to_uio: Skipping PCI device 0000:00:04.0 as host interface eth1 is up
+    vpp[10211]: dpdk_config:1240: EAL init args: -c 1 -n 4 --huge-dir /run/vpp/hugepages --file-prefix vpp -b 0000:00:03.0 -b 0000:00:04.0 --master-lcore 0 --socket-mem 64
+    EAL: No free hugepages reported in hugepages-1048576kB
+    EAL: Error - exiting with code: 1
+    Cause: Cannot create lock on '/var/run/.vpp_config'. Is another primary process running?
+
+Action: Send commands to VPP using vppctl
+---------------------------------------------------------------
+
+You can send vpp commands with a utility called *vppctl*.
+
+When running vppctl against a named version of vpp, you will need to run:
+
+.. code-block:: console
+   
+    sudo vppctl -s /run/vpp/cli-${name}.sock ${cmd}
+
+**Note** 
+
+.. code-block:: console
+    
+    /run/vpp/cli-${name}.sock
+
+is the particular naming convention used in this tutorial.  By default you can set vpp to use what ever socket file name you would like at startup (the default config file uses /run/vpp/cli.sock) if two different vpps are being run (as in this tutorial) you must use distinct socket files for each one.
+
+So to run 'show ver' against the vpp instance named vpp1 you would run:
+
+.. code-block:: console
+
+    sudo vppctl -s /run/vpp/cli-vpp1.sock show ver
+
+**Output:**
+
+.. code-block:: console
+    
+    vpp v17.04-rc0~177-g006eb47 built by ubuntu on fdio-ubuntu1604-sevt at Mon Jan 30 18:30:12 UTC 2017
+
+Action: Start a VPP shell using vppctl
+---------------------------------------------------------------
+You can also use vppctl to launch a vpp shell with which you can run multiple vpp commands interactively by running:
+
+.. code-block:: console
+    
+    sudo vppctl -s /run/vpp/cli-${name}.sock
+
+which will give you a command prompt.
+
+Try doing show ver that way:
+
+.. code-block:: console
+
+    sudo vppctl -s /run/vpp/cli-vpp1.sock
+    vpp# show ver
+
+Output:
+
+.. code-block:: console
+
+    vpp v17.04-rc0~177-g006eb47 built by ubuntu on fdio-ubuntu1604-sevt at Mon Jan 30 18:30:12 UTC 2017
+
+    vpp#
+
+To exit the vppctl shell:
+
+.. code-block:: console
+
+    vpp# quit
+
+Exercise: Create an interface
+-----------------------------
+
+Skills to be Learned
+^^^^^^^^^^^^^^^^^^^^
+
+#. Create a veth interface in Linux host
+#. Assign an IP address to one end of the veth interface in the Linux host
+#. Create a vpp host-interface that connected to one end of a veth interface via AF_PACKET
+#. Add an ip address to a vpp interface
+#. Setup a 'trace'
+#. View a 'trace'
+#. Clear a 'trace'
+#. Verify using ping from host
+#. Ping from vpp
+#. Examine Arp Table
+#. Examine ip fib
+
+VPP command learned in this exercise
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+#. `create host-interface <https://docs.fd.io/vpp/17.04/clicmd_src_vnet_devices_af_packet.html#clicmd_create_host-interface>`_
+#. `set int state <https://docs.fd.io/vpp/17.04/clicmd_src_vnet.html#clicmd_set_interface_state>`_
+#. `set int ip address <https://docs.fd.io/vpp/17.04/clicmd_src_vnet_ip.html#clicmd_set_interface_ip_address>`_
+#. `show hardware <https://docs.fd.io/vpp/17.04/clicmd_src_vnet.html#clicmd_show_hardware-interfaces>`_
+#. `show int <https://docs.fd.io/vpp/17.04/clicmd_src_vnet.html#clicmd_show_interfaces>`_
+#. `show int addr <https://docs.fd.io/vpp/17.04/clicmd_src_vnet.html#clicmd_show_interfaces>`_
+#. `trace add <https://docs.fd.io/vpp/17.04/clicmd_src_vlib.html#clicmd_trace_add>`_
+#. `clear trace <https://docs.fd.io/vpp/17.04/clicmd_src_vlib.html#clicmd_clear_trace>`_
+#. `ping <https://docs.fd.io/vpp/17.04/clicmd_src_vnet_ip.html#clicmd_ping>`_
+#. `show ip arp <https://docs.fd.io/vpp/17.04/clicmd_src_vnet_ethernet.html#clicmd_show_ip_arp>`_
+#. `show ip fib <https://docs.fd.io/vpp/17.04/clicmd_src_vnet_fib.html#clicmd_show_ip_fib>`_
+
+Topology
+~~~~~~~~
+
+.. figure:: /_images/Create_Interface_Topology.jpg
+  :alt: Figure: Create Interface Topology
+
+  Figure: Create Interface Topology
+
+Initial State
+~~~~~~~~~~~~~
+
+The initial state here is presumed to be the final state from the
+exercise `VPP Basics <VPP/Progressive_VPP_Tutorial#Exercise:_vpp_basics>`__
+ 
+Action: Create veth interfaces on host
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In Linux, there is a type of interface call 'veth'. Think of a 'veth'
+interface as being an interface that has two ends to it (rather than
+one).
+
+Create a veth interface with one end named **vpp1out** and the other
+named **vpp1host**
+
+::
+
+   sudo ip link add name vpp1out type veth peer name vpp1host
+
+Turn up both ends:
+
+::
+
+   sudo ip link set dev vpp1out up
+   sudo ip link set dev vpp1host up
+
+Assign an IP address
+
+::
+
+   sudo ip addr add 10.10.1.1/24 dev vpp1host
+
+Display the result:
+
+::
+
+   sudo ip addr show vpp1host
+
+Example Output:
+
+::
+
+   10: vpp1host@vpp1out: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
+       link/ether 5e:97:e3:41:aa:b8 brd ff:ff:ff:ff:ff:ff
+       inet 10.10.1.1/24 scope global vpp1host
+          valid_lft forever preferred_lft forever
+       inet6 fe80::5c97:e3ff:fe41:aab8/64 scope link 
+          valid_lft forever preferred_lft forever
+
+Action: Create vpp host- interface
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Create a host interface attached to **vpp1out**.
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock create host-interface name vpp1out
+
+Output:
+
+::
+
+   host-vpp1out
+
+Confirm the interface:
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock show hardware
+
+Example Output:
+
+::
+
+                 Name                Idx   Link  Hardware
+   host-vpp1out                       1     up   host-vpp1out
+     Ethernet address 02:fe:48:ec:d5:a7
+     Linux PACKET socket interface
+   local0                             0    down  local0
+     local
+
+Turn up the interface:
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock set int state host-vpp1out up
+
+Confirm the interface is up:
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock show int
+
+::
+
+                 Name               Idx       State          Counter          Count     
+   host-vpp1out                      1         up       
+   local0                            0        down
+
+Assign ip address 10.10.1.2/24
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock set int ip address host-vpp1out 10.10.1.2/24
+
+Confirm the ip address is assigned:
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock show int addr
+
+::
+
+   host-vpp1out (up):
+     10.10.1.2/24
+   local0 (dn):
+
+Action: Add trace
+~~~~~~~~~~~~~~~~~
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock trace add af-packet-input 10
+
+Action: Ping from host to vpp
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   ping -c 1 10.10.1.2
+
+::
+
+   PING 10.10.1.2 (10.10.1.2) 56(84) bytes of data.
+   64 bytes from 10.10.1.2: icmp_seq=1 ttl=64 time=0.557 ms
+
+   --- 10.10.1.2 ping statistics ---
+   1 packets transmitted, 1 received, 0% packet loss, time 0ms
+   rtt min/avg/max/mdev = 0.557/0.557/0.557/0.000 ms
+
+Action: Examine Trace of ping from host to vpp
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock show trace
+
+::
+
+   ------------------- Start of thread 0 vpp_main -------------------
+   Packet 1
+
+   00:09:30:397798: af-packet-input
+     af_packet: hw_if_index 1 next-index 4
+       tpacket2_hdr:
+         status 0x20000001 len 42 snaplen 42 mac 66 net 80
+         sec 0x588fd3ac nsec 0x375abde7 vlan 0 vlan_tpid 0
+   00:09:30:397906: ethernet-input
+     ARP: fa:13:55:ac:d9:50 -> ff:ff:ff:ff:ff:ff
+   00:09:30:397912: arp-input
+     request, type ethernet/IP4, address size 6/4
+     fa:13:55:ac:d9:50/10.10.1.1 -> 00:00:00:00:00:00/10.10.1.2
+   00:09:30:398191: host-vpp1out-output
+     host-vpp1out
+     ARP: 02:fe:48:ec:d5:a7 -> fa:13:55:ac:d9:50
+     reply, type ethernet/IP4, address size 6/4
+     02:fe:48:ec:d5:a7/10.10.1.2 -> fa:13:55:ac:d9:50/10.10.1.1
+
+   Packet 2
+
+   00:09:30:398227: af-packet-input
+     af_packet: hw_if_index 1 next-index 4
+       tpacket2_hdr:
+         status 0x20000001 len 98 snaplen 98 mac 66 net 80
+         sec 0x588fd3ac nsec 0x37615060 vlan 0 vlan_tpid 0
+   00:09:30:398295: ethernet-input
+     IP4: fa:13:55:ac:d9:50 -> 02:fe:48:ec:d5:a7
+   00:09:30:398298: ip4-input
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x9b46
+       fragment id 0x894c, flags DONT_FRAGMENT
+     ICMP echo_request checksum 0x83c
+   00:09:30:398300: ip4-lookup
+     fib 0 dpo-idx 5 flow hash: 0x00000000
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x9b46
+       fragment id 0x894c, flags DONT_FRAGMENT
+     ICMP echo_request checksum 0x83c
+   00:09:30:398303: ip4-local
+       ICMP: 10.10.1.1 -> 10.10.1.2
+         tos 0x00, ttl 64, length 84, checksum 0x9b46
+         fragment id 0x894c, flags DONT_FRAGMENT
+       ICMP echo_request checksum 0x83c
+   00:09:30:398305: ip4-icmp-input
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x9b46
+       fragment id 0x894c, flags DONT_FRAGMENT
+     ICMP echo_request checksum 0x83c
+   00:09:30:398307: ip4-icmp-echo-request
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x9b46
+       fragment id 0x894c, flags DONT_FRAGMENT
+     ICMP echo_request checksum 0x83c
+   00:09:30:398317: ip4-load-balance
+     fib 0 dpo-idx 10 flow hash: 0x0000000e
+     ICMP: 10.10.1.2 -> 10.10.1.1
+       tos 0x00, ttl 64, length 84, checksum 0xbef3
+       fragment id 0x659f, flags DONT_FRAGMENT
+     ICMP echo_reply checksum 0x103c
+   00:09:30:398318: ip4-rewrite
+     tx_sw_if_index 1 dpo-idx 2 : ipv4 via 10.10.1.1 host-vpp1out: IP4: 02:fe:48:ec:d5:a7 -> fa:13:55:ac:d9:50 flow hash: 0x00000000
+     IP4: 02:fe:48:ec:d5:a7 -> fa:13:55:ac:d9:50
+     ICMP: 10.10.1.2 -> 10.10.1.1
+       tos 0x00, ttl 64, length 84, checksum 0xbef3
+       fragment id 0x659f, flags DONT_FRAGMENT
+     ICMP echo_reply checksum 0x103c
+   00:09:30:398320: host-vpp1out-output
+     host-vpp1out
+     IP4: 02:fe:48:ec:d5:a7 -> fa:13:55:ac:d9:50
+     ICMP: 10.10.1.2 -> 10.10.1.1
+       tos 0x00, ttl 64, length 84, checksum 0xbef3
+       fragment id 0x659f, flags DONT_FRAGMENT
+     ICMP echo_reply checksum 0x103c
+
+Action: Clear trace buffer
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock clear  trace
+
+Action: ping from vpp to host
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock ping 10.10.1.1
+
+::
+
+   64 bytes from 10.10.1.1: icmp_seq=1 ttl=64 time=.0865 ms
+   64 bytes from 10.10.1.1: icmp_seq=2 ttl=64 time=.0914 ms
+   64 bytes from 10.10.1.1: icmp_seq=3 ttl=64 time=.0943 ms
+   64 bytes from 10.10.1.1: icmp_seq=4 ttl=64 time=.0959 ms
+   64 bytes from 10.10.1.1: icmp_seq=5 ttl=64 time=.0858 ms
+
+   Statistics: 5 sent, 5 received, 0% packet loss
+
+Action: Examine Trace of ping from vpp to host
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock show trace
+
+::
+
+   ------------------- Start of thread 0 vpp_main -------------------
+   Packet 1
+
+   00:12:47:155326: af-packet-input
+     af_packet: hw_if_index 1 next-index 4
+       tpacket2_hdr:
+         status 0x20000001 len 98 snaplen 98 mac 66 net 80
+         sec 0x588fd471 nsec 0x161c61ad vlan 0 vlan_tpid 0
+   00:12:47:155331: ethernet-input
+     IP4: fa:13:55:ac:d9:50 -> 02:fe:48:ec:d5:a7
+   00:12:47:155334: ip4-input
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x2604
+       fragment id 0x3e8f
+     ICMP echo_reply checksum 0x1a83
+   00:12:47:155335: ip4-lookup
+     fib 0 dpo-idx 5 flow hash: 0x00000000
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x2604
+       fragment id 0x3e8f
+     ICMP echo_reply checksum 0x1a83
+   00:12:47:155336: ip4-local
+       ICMP: 10.10.1.1 -> 10.10.1.2
+         tos 0x00, ttl 64, length 84, checksum 0x2604
+         fragment id 0x3e8f
+       ICMP echo_reply checksum 0x1a83
+   00:12:47:155339: ip4-icmp-input
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x2604
+       fragment id 0x3e8f
+     ICMP echo_reply checksum 0x1a83
+   00:12:47:155342: ip4-icmp-echo-reply
+     ICMP echo id 17572 seq 1
+   00:12:47:155349: error-drop
+     ip4-icmp-input: unknown type
+
+   Packet 2
+
+   00:12:48:155330: af-packet-input
+     af_packet: hw_if_index 1 next-index 4
+       tpacket2_hdr:
+         status 0x20000001 len 98 snaplen 98 mac 66 net 80
+         sec 0x588fd472 nsec 0x1603e95b vlan 0 vlan_tpid 0
+   00:12:48:155337: ethernet-input
+     IP4: fa:13:55:ac:d9:50 -> 02:fe:48:ec:d5:a7
+   00:12:48:155341: ip4-input
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x2565
+       fragment id 0x3f2e
+     ICMP echo_reply checksum 0x7405
+   00:12:48:155343: ip4-lookup
+     fib 0 dpo-idx 5 flow hash: 0x00000000
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x2565
+       fragment id 0x3f2e
+     ICMP echo_reply checksum 0x7405
+   00:12:48:155344: ip4-local
+       ICMP: 10.10.1.1 -> 10.10.1.2
+         tos 0x00, ttl 64, length 84, checksum 0x2565
+         fragment id 0x3f2e
+       ICMP echo_reply checksum 0x7405
+   00:12:48:155346: ip4-icmp-input
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x2565
+       fragment id 0x3f2e
+     ICMP echo_reply checksum 0x7405
+   00:12:48:155348: ip4-icmp-echo-reply
+     ICMP echo id 17572 seq 2
+   00:12:48:155351: error-drop
+     ip4-icmp-input: unknown type
+
+   Packet 3
+
+   00:12:49:155331: af-packet-input
+     af_packet: hw_if_index 1 next-index 4
+       tpacket2_hdr:
+         status 0x20000001 len 98 snaplen 98 mac 66 net 80
+         sec 0x588fd473 nsec 0x15eb77ef vlan 0 vlan_tpid 0
+   00:12:49:155337: ethernet-input
+     IP4: fa:13:55:ac:d9:50 -> 02:fe:48:ec:d5:a7
+   00:12:49:155341: ip4-input
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x249e
+       fragment id 0x3ff5
+     ICMP echo_reply checksum 0xf446
+   00:12:49:155343: ip4-lookup
+     fib 0 dpo-idx 5 flow hash: 0x00000000
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x249e
+       fragment id 0x3ff5
+     ICMP echo_reply checksum 0xf446
+   00:12:49:155345: ip4-local
+       ICMP: 10.10.1.1 -> 10.10.1.2
+         tos 0x00, ttl 64, length 84, checksum 0x249e
+         fragment id 0x3ff5
+       ICMP echo_reply checksum 0xf446
+   00:12:49:155349: ip4-icmp-input
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x249e
+       fragment id 0x3ff5
+     ICMP echo_reply checksum 0xf446
+   00:12:49:155350: ip4-icmp-echo-reply
+     ICMP echo id 17572 seq 3
+   00:12:49:155354: error-drop
+     ip4-icmp-input: unknown type
+
+   Packet 4
+
+   00:12:50:155335: af-packet-input
+     af_packet: hw_if_index 1 next-index 4
+       tpacket2_hdr:
+         status 0x20000001 len 98 snaplen 98 mac 66 net 80
+         sec 0x588fd474 nsec 0x15d2ffb6 vlan 0 vlan_tpid 0
+   00:12:50:155341: ethernet-input
+     IP4: fa:13:55:ac:d9:50 -> 02:fe:48:ec:d5:a7
+   00:12:50:155346: ip4-input
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x2437
+       fragment id 0x405c
+     ICMP echo_reply checksum 0x5b6e
+   00:12:50:155347: ip4-lookup
+     fib 0 dpo-idx 5 flow hash: 0x00000000
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x2437
+       fragment id 0x405c
+     ICMP echo_reply checksum 0x5b6e
+   00:12:50:155350: ip4-local
+       ICMP: 10.10.1.1 -> 10.10.1.2
+         tos 0x00, ttl 64, length 84, checksum 0x2437
+         fragment id 0x405c
+       ICMP echo_reply checksum 0x5b6e
+   00:12:50:155351: ip4-icmp-input
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x2437
+       fragment id 0x405c
+     ICMP echo_reply checksum 0x5b6e
+   00:12:50:155353: ip4-icmp-echo-reply
+     ICMP echo id 17572 seq 4
+   00:12:50:155356: error-drop
+     ip4-icmp-input: unknown type
+
+   Packet 5
+
+   00:12:51:155324: af-packet-input
+     af_packet: hw_if_index 1 next-index 4
+       tpacket2_hdr:
+         status 0x20000001 len 98 snaplen 98 mac 66 net 80
+         sec 0x588fd475 nsec 0x15ba8726 vlan 0 vlan_tpid 0
+   00:12:51:155331: ethernet-input
+     IP4: fa:13:55:ac:d9:50 -> 02:fe:48:ec:d5:a7
+   00:12:51:155335: ip4-input
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x23cc
+       fragment id 0x40c7
+     ICMP echo_reply checksum 0xedb3
+   00:12:51:155337: ip4-lookup
+     fib 0 dpo-idx 5 flow hash: 0x00000000
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x23cc
+       fragment id 0x40c7
+     ICMP echo_reply checksum 0xedb3
+   00:12:51:155338: ip4-local
+       ICMP: 10.10.1.1 -> 10.10.1.2
+         tos 0x00, ttl 64, length 84, checksum 0x23cc
+         fragment id 0x40c7
+       ICMP echo_reply checksum 0xedb3
+   00:12:51:155341: ip4-icmp-input
+     ICMP: 10.10.1.1 -> 10.10.1.2
+       tos 0x00, ttl 64, length 84, checksum 0x23cc
+       fragment id 0x40c7
+     ICMP echo_reply checksum 0xedb3
+   00:12:51:155343: ip4-icmp-echo-reply
+     ICMP echo id 17572 seq 5
+   00:12:51:155346: error-drop
+     ip4-icmp-input: unknown type
+
+   Packet 6
+
+   00:12:52:175185: af-packet-input
+     af_packet: hw_if_index 1 next-index 4
+       tpacket2_hdr:
+         status 0x20000001 len 42 snaplen 42 mac 66 net 80
+         sec 0x588fd476 nsec 0x16d05dd0 vlan 0 vlan_tpid 0
+   00:12:52:175195: ethernet-input
+     ARP: fa:13:55:ac:d9:50 -> 02:fe:48:ec:d5:a7
+   00:12:52:175200: arp-input
+     request, type ethernet/IP4, address size 6/4
+     fa:13:55:ac:d9:50/10.10.1.1 -> 00:00:00:00:00:00/10.10.1.2
+   00:12:52:175214: host-vpp1out-output
+     host-vpp1out
+     ARP: 02:fe:48:ec:d5:a7 -> fa:13:55:ac:d9:50
+     reply, type ethernet/IP4, address size 6/4
+     02:fe:48:ec:d5:a7/10.10.1.2 -> fa:13:55:ac:d9:50/10.10.1.1
+
+After examinging the trace, clear it again.
+
+Action: Examine arp tables
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock show ip arp
+
+::
+
+       Time           IP4       Flags      Ethernet              Interface       
+       570.4092    10.10.1.1      D    fa:13:55:ac:d9:50       host-vpp1out      
+
+Action: Examine routing table
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock show ip fib
+
+::
+
+   ipv4-VRF:0, fib_index 0, flow hash: src dst sport dport proto 
+   0.0.0.0/0
+     unicast-ip4-chain
+     [@0]: dpo-load-balance: [index:0 buckets:1 uRPF:0 to:[0:0]]
+       [0] [@0]: dpo-drop ip4
+   0.0.0.0/32
+     unicast-ip4-chain
+     [@0]: dpo-load-balance: [index:1 buckets:1 uRPF:1 to:[0:0]]
+       [0] [@0]: dpo-drop ip4
+   10.10.1.1/32
+     unicast-ip4-chain
+     [@0]: dpo-load-balance: [index:10 buckets:1 uRPF:9 to:[5:420] via:[1:84]]
+       [0] [@5]: ipv4 via 10.10.1.1 host-vpp1out: IP4: 02:fe:48:ec:d5:a7 -> fa:13:55:ac:d9:50
+   10.10.1.0/24
+     unicast-ip4-chain
+     [@0]: dpo-load-balance: [index:8 buckets:1 uRPF:7 to:[0:0]]
+       [0] [@4]: ipv4-glean: host-vpp1out
+   10.10.1.2/32
+     unicast-ip4-chain
+     [@0]: dpo-load-balance: [index:9 buckets:1 uRPF:8 to:[6:504]]
+       [0] [@2]: dpo-receive: 10.10.1.2 on host-vpp1out
+   224.0.0.0/4
+     unicast-ip4-chain
+     [@0]: dpo-load-balance: [index:3 buckets:1 uRPF:3 to:[0:0]]
+       [0] [@0]: dpo-drop ip4
+   240.0.0.0/4
+     unicast-ip4-chain
+     [@0]: dpo-load-balance: [index:2 buckets:1 uRPF:2 to:[0:0]]
+       [0] [@0]: dpo-drop ip4
+   255.255.255.255/32
+     unicast-ip4-chain
+     [@0]: dpo-load-balance: [index:4 buckets:1 uRPF:4 to:[0:0]]
+       [0] [@0]: dpo-drop ip4
+
+Exercise: Connecting two vpp instances
+--------------------------------------
+
+.. _background-1:
+
+Background
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+memif is a very high performance, direct memory interface type which can
+be used between vpp instances to form a topology. It uses a file socket
+for a control channel to set up that shared memory.
+
+.. _skills-to-be-learned-1:
+
+Skills to be Learned
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+You will learn the following new skill in this exercise:
+
+#. Create a memif interface between two vpp instances
+
+You should be able to perform this exercise with the following skills
+learned in previous exercises:
+
+#. Run a second vpp instance
+#. Add an ip address to a vpp interface
+#. Ping from vpp
+
+.. _topology-1:
+
+Topology
+^^^^^^^^^^^^^
+
+.. figure:: /_images/Connecting_two_vpp_instances_with_memif.png
+   :alt: Connect two vpp topolgy
+
+   Connect two vpp topolgy
+
+.. _initial-state-1:
+
+Initial state
+^^^^^^^^^^^^^
+
+The initial state here is presumed to be the final state from the
+exercise `Create an
+Interface <VPP/Progressive_VPP_Tutorial#Exercise:_Create_an_Interface>`__
+
+.. _action-running-a-second-vpp-instances-1:
+
+Action: Running a second vpp instances
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+You should already have a vpp instance running named: vpp1.
+
+Run a second vpp instance named: vpp2.
+
+.. _action-create-memif-interface-on-vpp1-1:
+
+Action: Create memif interface on vpp1
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Create a memif interface on vpp1:
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock create memif id 0 master
+
+This will create an interface on vpp1 memif0/0 using /run/vpp/memif as
+its socket file. The role of vpp1 for this memif inteface is 'master'.
+
+Use your previously used skills to:
+
+#. Set the memif0/0 state to up.
+#. Assign IP address 10.10.2.1/24 to memif0/0
+#. Examine memif0/0 via show commands
+
+.. _action-create-memif-interface-on-vpp2-1:
+
+Action: Create memif interface on vpp2
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+We want vpp2 to pick up the 'slave' role using the same
+run/vpp/memif-vpp1vpp2 socket file
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp2.sock create memif id 0 slave
+
+This will create an interface on vpp2 memif0/0 using /run/vpp/memif as
+its socket file. The role of vpp1 for this memif inteface is 'slave'.
+
+Use your previously used skills to:
+
+#. Set the memif0/0 state to up.
+#. Assign IP address 10.10.2.2/24 to memif0/0
+#. Examine memif0/0 via show commands
+
+.. _action-ping-from-vpp1-to-vpp2-1:
+
+Action: Ping from vpp1 to vpp2
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Ping 10.10.2.2 from vpp1
+
+Ping 10.10.2.1 from vpp2
+
+Exercise: Routing
+-----------------
+
+Skills to be Learned
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+In this exercise you will learn these new skills:
+
+#. Add route to Linux Host routing table
+#. Add route to vpp routing table
+
+And revisit the old ones:
+
+#. Examine vpp routing table
+#. Enable trace on vpp1 and vpp2
+#. ping from host to vpp
+#. Examine and clear trace on vpp1 and vpp2
+#. ping from vpp to host
+#. Examine and clear trace on vpp1 and vpp2
+
+vpp command learned in this exercise
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. `ip route
+   add <https://docs.fd.io/vpp/17.04/clicmd_src_vnet_ip.html#clicmd_ip_route>`__
+
+Topology
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. figure:: /_images/Connecting_two_vpp_instances_with_memif.png
+   :alt: Connect two vpp topology
+
+   Connect two vpp topology
+
+Initial State
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The initial state here is presumed to be the final state from the
+exercise `Connecting two vpp
+instances <VPP/Progressive_VPP_Tutorial#Connecting_two_vpp_instances>`__
+
+Action: Setup host route
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+::
+
+   sudo ip route add 10.10.2.0/24 via 10.10.1.2
+   ip route
+
+::
+
+   default via 10.0.2.2 dev enp0s3 
+   10.0.2.0/24 dev enp0s3  proto kernel  scope link  src 10.0.2.15 
+   10.10.1.0/24 dev vpp1host  proto kernel  scope link  src 10.10.1.1 
+   10.10.2.0/24 via 10.10.1.2 dev vpp1host 
+
+Setup return route on vpp2
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp2.sock ip route add 10.10.1.0/24  via 10.10.2.1
+
+Ping from host through vpp1 to vpp2
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. Setup a trace on vpp1 and vpp2
+#. Ping 10.10.2.2 from the host
+#. Examine the trace on vpp1 and vpp2
+#. Clear the trace on vpp1 and vpp2
+
+Exercise: Switching
+-------------------
+
+Skills to be Learned
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. Associate an interface with a bridge domain
+#. Create a loopback interaface
+#. Create a BVI (Bridge Virtual Interface) for a bridge domain
+#. Examine a bridge domain
+
+vpp command learned in this exercise
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. `show
+   bridge <https://docs.fd.io/vpp/17.04/clicmd_src_vnet_l2.html#clicmd_show_bridge-domain>`__
+#. `show bridge
+   detail <https://docs.fd.io/vpp/17.04/clicmd_src_vnet_l2.html#clicmd_show_bridge-domain>`__
+#. `set int l2
+   bridge <https://docs.fd.io/vpp/17.04/clicmd_src_vnet_l2.html#clicmd_set_interface_l2_bridge>`__
+#. `show l2fib
+   verbose <https://docs.fd.io/vpp/17.04/clicmd_src_vnet_l2.html#clicmd_show_l2fib>`__
+
+Topology
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. figure:: /_images/Switching_Topology.jpg
+   :alt: Switching Topology
+
+   Switching Topology
+
+Initial state
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Unlike previous exercises, for this one you want to start tabula rasa.
+
+Note: You will lose all your existing config in your vpp instances!
+
+To clear existing config from previous exercises run:
+
+::
+
+   ps -ef | grep vpp | awk '{print $2}'| xargs sudo kill
+   sudo ip link del dev vpp1host
+   sudo ip link del dev vpp1vpp2
+
+Action: Run vpp instances
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. Run a vpp instance named **vpp1**
+#. Run a vpp instance named **vpp2**
+
+Action: Connect vpp1 to host
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. Create a veth with one end named vpp1host and the other named
+   vpp1out.
+#. Connect vpp1out to vpp1
+#. Add ip address 10.10.1.1/24 on vpp1host
+
+Action: Connect vpp1 to vpp2
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. Create a veth with one end named vpp1vpp2 and the other named
+   vpp2vpp1.
+#. Connect vpp1vpp2 to vpp1.
+#. Connect vpp2vpp1 to vpp2.
+
+Action: Configure Bridge Domain on vpp1
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Check to see what bridge domains already exist, and select the first
+bridge domain number not in use:
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock show bridge-domain
+
+::
+
+     ID   Index   Learning   U-Forwrd   UU-Flood   Flooding   ARP-Term     BVI-Intf   
+     0      0        off        off        off        off        off        local0    
+
+In the example above, there is bridge domain ID '0' already. Even though
+sometimes we might get feedback as below:
+
+::
+
+   no bridge-domains in use
+
+the bridge domain ID '0' still exists, where no operations are
+supported. For instance, if we try to add host-vpp1out and host-vpp1vpp2
+to bridge domain ID 0, we will get nothing setup.
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock set int l2 bridge host-vpp1out 0
+   sudo vppctl -s /run/vpp/cli-vpp1.sock set int l2 bridge host-vpp1vpp2 0
+   sudo vppctl -s /run/vpp/cli-vpp1.sock show bridge-domain 0 detail
+
+::
+
+   show bridge-domain: No operations on the default bridge domain are supported
+
+So we will create bridge domain 1 instead of playing with the default
+bridge domain ID 0.
+
+Add host-vpp1out to bridge domain ID 1
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock set int l2 bridge host-vpp1out 1
+
+Add host-vpp1vpp2 to bridge domain ID1
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock set int l2 bridge host-vpp1vpp2  1
+
+Examine bridge domain 1:
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock show bridge-domain 1 detail
+
+::
+
+     BD-ID   Index   BSN  Age(min)  Learning  U-Forwrd  UU-Flood  Flooding  ARP-Term  BVI-Intf
+       1       1      0     off        on        on        on        on       off       N/A
+
+              Interface           If-idx ISN  SHG  BVI  TxFlood        VLAN-Tag-Rewrite
+            host-vpp1out            1     1    0    -      *                 none
+            host-vpp1vpp2           2     1    0    -      *                 none
+
+Action: Configure loopback interface on vpp2
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp2.sock create loopback interface
+
+::
+
+   loop0
+
+Add the ip address 10.10.1.2/24 to vpp2 interface loop0. Set the state
+of interface loop0 on vpp2 to 'up'
+
+Action: Configure bridge domain on vpp2
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Check to see the first available bridge domain ID (it will be 1 in this
+case)
+
+Add interface loop0 as a bridge virtual interface (bvi) to bridge domain
+1
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp2.sock set int l2 bridge loop0 1 bvi
+
+Add interface vpp2vpp1 to bridge domain 1
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp2.sock set int l2 bridge host-vpp2vpp1  1
+
+Examine the bridge domain and interfaces.
+
+Action: Ping from host to vpp and vpp to host
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. Add trace on vpp1 and vpp2
+#. ping from host to 10.10.1.2
+#. Examine and clear trace on vpp1 and vpp2
+#. ping from vpp2 to 10.10.1.1
+#. Examine and clear trace on vpp1 and vpp2
+
+Action: Examine l2 fib
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock show l2fib verbose
+
+::
+
+       Mac Address     BD Idx           Interface           Index  static  filter  bvi   Mac Age (min) 
+    de:ad:00:00:00:00    1            host-vpp1vpp2           2       0       0     0      disabled    
+    c2:f6:88:31:7b:8e    1            host-vpp1out            1       0       0     0      disabled    
+   2 l2fib entries
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp2.sock show l2fib verbose
+
+::
+
+       Mac Address     BD Idx           Interface           Index  static  filter  bvi   Mac Age (min) 
+    de:ad:00:00:00:00    1                loop0               2       1       0     1      disabled    
+    c2:f6:88:31:7b:8e    1            host-vpp2vpp1           1       0       0     0      disabled    
+   2 l2fib entries
+
+Source NAT
+----------
+
+Skills to be Learned
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. Abusing networks namespaces for fun and profit
+#. Configuring snat address
+#. Configuring snat inside and outside interfaces
+
+vpp command learned in this exercise
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. `snat add interface
+   address <https://docs.fd.io/vpp/17.04/clicmd_src_plugins_snat.html#clicmd_snat_add_interface_address>`__
+#. `set interface
+   snat <https://docs.fd.io/vpp/17.04/clicmd_src_plugins_snat.html#clicmd_set_interface_snat>`__
+
+Topology
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. figure:: /_images/SNAT_Topology.jpg
+   :alt: SNAT Topology
+
+   SNAT Topology
+
+Initial state
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Unlike previous exercises, for this one you want to start tabula rasa.
+
+Note: You will lose all your existing config in your vpp instances!
+
+To clear existing config from previous exercises run:
+
+::
+
+   ps -ef | grep vpp | awk '{print $2}'| xargs sudo kill
+   sudo ip link del dev vpp1host
+   sudo ip link del dev vpp1vpp2
+
+Action: Install vpp-plugins
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Snat is supported by a plugin, so vpp-plugins need to be installed
+
+::
+
+   sudo apt-get install vpp-plugins
+
+Action: Create vpp instance
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Create one vpp instance named vpp1.
+
+Confirm snat plugin is present:
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock show plugins
+
+::
+
+    Plugin path is: /usr/lib/vpp_plugins
+    Plugins loaded: 
+     1.ioam_plugin.so
+     2.ila_plugin.so
+     3.acl_plugin.so
+     4.flowperpkt_plugin.so
+     5.snat_plugin.so
+     6.libsixrd_plugin.so
+     7.lb_plugin.so
+
+Action: Create veth interfaces
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. Create a veth interface with one end named vpp1outside and the other
+   named vpp1outsidehost
+#. Assign IP address 10.10.1.1/24 to vpp1outsidehost
+#. Create a veth interface with one end named vpp1inside and the other
+   named vpp1insidehost
+#. Assign IP address 10.10.2.1/24 to vpp1outsidehost
+
+Because we'd like to be able to route \*via\* our vpp instance to an
+interface on the same host, we are going to put vpp1insidehost into a
+network namespace
+
+Create a new network namespace 'inside'
+
+::
+
+   sudo ip netns add inside
+
+Move interface vpp1inside into the 'inside' namespace:
+
+::
+
+   sudo ip link set dev vpp1insidehost up netns inside
+
+Assign an ip address to vpp1insidehost
+
+::
+
+   sudo ip netns exec inside ip addr add 10.10.2.1/24 dev vpp1insidehost
+
+Create a route inside the netns:
+
+::
+
+   sudo ip netns exec inside ip route add 10.10.1.0/24 via 10.10.2.2
+
+Action: Configure vpp outside interface
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. Create a vpp host interface connected to vpp1outside
+#. Assign ip address 10.10.1.2/24
+#. Create a vpp host interface connected to vpp1inside
+#. Assign ip address 10.10.2.2/24
+
+Action: Configure snat
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Configure snat to use the address of host-vpp1outside
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock snat add interface address host-vpp1outside
+
+Configure snat inside and outside interfaces
+
+::
+
+   sudo vppctl -s /run/vpp/cli-vpp1.sock set interface snat in host-vpp1inside out host-vpp1outside
+
+Action: Prepare to Observe Snat
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Observing snat in this configuration is interesting. To do so, vagrant
+ssh a second time into your VM and run:
+
+::
+
+   sudo tcpdump -s 0 -i vpp1outsidehost
+
+Also enable tracing on vpp1
+
+Action: Ping via snat
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+::
+
+   sudo ip netns exec inside ping -c 1 10.10.1.1
+
+Action: Confirm snat
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Examine the tcpdump output and vpp1 trace to confirm snat occurred.
+