docs: Add Ray's ACL use case

Change-Id: Id99f16953a23a4be4cc1fb94419ea8282fa720e8
Signed-off-by: jdenisco <jdenisco@cisco.com>

5 files changed, 489 insertions, 0 deletions

diff --git a/docs/_images/ip4-2n-iacl.png b/docs/_images/ip4-2n-iacl.png
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diff --git a/docs/_images/ip4-3n-oacl.png b/docs/_images/ip4-3n-oacl.png
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diff --git a/docs/_images/ip4-acl-features-ndr.png b/docs/_images/ip4-acl-features-ndr.png
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diff --git a/docs/usecases/acls.rst b/docs/usecases/acls.rst
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+.. _aclwithvpp:
+
+Access Control Lists (ACLs) with FD.io VPP
+==========================================
+
+This section is overview of the options available to implement ACLs in
+FD.io VPP. As there are a number of way's to address ACL-like functionality,
+it is worth a separate survey of these options with some commentary on
+features and performance
+
+All performance numbers and examples from this document are reused from
+the `FD.io CSIT v19.04 performance report <https://docs.fd.io/csit/rls1904/report/>`__
+All information and performance is accurate for
+`FD.io VPP 19.04 <https://git.fd.io/vpp/tag/?h=v19.04>`__ release. The
+sections *performance* & *operational data* below correlate directly with
+those sections from the FD.io CSIT performance report.
+
+Summary
+-------
+
++---------------------+-----------+-----------------------------------+
+| Option              | Relative  | Features & Notes                  |
+|                     | Performan |                                   |
+|                     | ce        |                                   |
++=====================+===========+===================================+
+| :ref:`aclplugin`    | Lowest    | Match on restricted L2-L4 fields, |
+|                     |           | stateful & stateless              |
++---------------------+-----------+-----------------------------------+
+| :ref:`vppcop`       | Highest   | Match on Layer 3 IPs, stateless   |
+|                     | (software |                                   |
+|                     | only)     |                                   |
++---------------------+-----------+-----------------------------------+
+| :ref:`vppflow`      | Highest   | Match on restricted L2-L4 fields, |
+|                     | (accelera | stateless, limited number of      |
+|                     | ted)      | flows                             |
++---------------------+-----------+-----------------------------------+
+| :ref:`classifiers`  | TBD       | Match on any field in the first   |
+|                     |           | 80 bytes, Not measured            |
++---------------------+-----------+-----------------------------------+
+
+FD.io VPP ACL Options
+---------------------
+
+.. _aclplugin:
+
+The FD.io VPP ACL Plugin
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+The plugin was originally developed as part of FD.io VPP and OpenStack
+integration. The plugin needs to be enabled on specific interfaces.
+
+Supports stateful and stateless ACLs on …
+""""""""""""""""""""""""""""""""""""""""""
+
+- MACs
+- IPS
+- UDP Ports
+- TCP Ports & Flags
+- ICMP Messages
+
+Directional
+"""""""""""
+
+* Input ACLs
+
+  * Run before the IP flow classification.
+
+* ACLs
+
+  * Run before interface output.
+
+Actions
+"""""""
+- Permit (sl)
+- Drop (sf)
+- Permit+Reflect (sf)
+
+Stateful (sf)
+"""""""""""""
+
+- Actions: permit+reflect
+- Most heavily optimized, as are the most common use case.
+- Faster because stateful uses a flow cache, it means the ACL hit is only taken once, up front for the flow and then becomes just look-up.
+- Uses more memory, less deterministic as the flow cache makes it
+  more susceptible to the effects of the memory hierarchy and
+  locality.
+
+Stateless (sl)
+""""""""""""""
+
+-  Actions : permit, drop
+-  Less optimized, less common use case.
+-  Slower as there is no flow-cache, every new packet incurs the same
+   amount ACL processing.
+-  Uses less memory, and are more deterministic (compared to
+   stateful).
+
+Operational Data
+----------------
+
+Input/Stateless
+~~~~~~~~~~~~~~~
+
+Test Case: 10ge2p1x520-ethip4udp-ip4base-iacl1sl-10kflows-ndrpdr
+""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+.. code-block:: console
+
+       DUT1: 
+       Thread 0 vpp_main (lcore 1) 
+       Time 3.8, average vectors/node 0.00, last 128 main loops 0.00 per node 0.00 
+         vector rates in 0.0000e0, out 0.0000e0, drop 0.0000e0, punt 0.0000e0 
+                    Name                 State         Calls          Vectors        Suspends         Clocks       Vectors/Call   
+       acl-plugin-fa-cleaner-process   any wait                 0               0              14          1.29e3            0.00 
+       acl-plugin-fa-worker-cleaner-pinterrupt wa               7               0               0          9.18e2            0.00 
+       api-rx-from-ring                 active                  0               0              52          8.96e4            0.00 
+       dpdk-process                    any wait                 0               0               1          1.35e4            0.00 
+       fib-walk                        any wait                 0               0               2          2.69e3            0.00 
+       ip6-icmp-neighbor-discovery-ev  any wait                 0               0               4          1.32e3            0.00 
+       lisp-retry-service              any wait                 0               0               2          2.90e3            0.00 
+       unix-epoll-input                 polling              7037               0               0          1.25e6            0.00 
+       vpe-oam-process                 any wait                 0               0               2          2.28e3            0.00 
+
+       Thread 1 vpp_wk_0 (lcore 2) 
+       Time 3.8, average vectors/node 249.02, last 128 main loops 32.00 per node 273.07 
+         vector rates in 6.1118e6, out 6.1118e6, drop 0.0000e0, punt 0.0000e0 
+                    Name                 State         Calls          Vectors        Suspends         Clocks       Vectors/Call   
+       TenGigabitEtherneta/0/0-output   active              47106        11721472               0          9.47e0          248.83 
+       TenGigabitEtherneta/0/0-tx       active              47106        11721472               0          4.22e1          248.83 
+       TenGigabitEtherneta/0/1-output   active              47106        11721472               0          1.02e1          248.83 
+       TenGigabitEtherneta/0/1-tx       active              47106        11721472               0          4.18e1          248.83 
+       acl-plugin-fa-worker-cleaner-pinterrupt wa               7               0               0          1.39e3            0.00 
+       acl-plugin-in-ip4-fa             active              94107        23442944               0          1.75e2          249.11 
+       dpdk-input                       polling             47106        23442944               0          4.64e1          497.66 
+       ethernet-input                   active              94212        23442944               0          1.55e1          248.83 
+       ip4-input-no-checksum            active              94107        23442944               0          3.23e1          249.11 
+       ip4-lookup                       active              94107        23442944               0          2.91e1          249.11 
+       ip4-rewrite                      active              94107        23442944               0          2.48e1          249.11 
+       unix-epoll-input                 polling                46               0               0          1.54e3            0.00
+
+Input/Stateful
+~~~~~~~~~~~~~~
+
+Test Case: 64b-1t1c-ethip4udp-ip4base-iacl1sf-10kflows-ndrpdr
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+.. code-block:: console
+
+       DUT1: 
+       Thread 0 vpp_main (lcore 1) 
+       Time 3.9, average vectors/node 0.00, last 128 main loops 0.00 per node 0.00 
+         vector rates in 0.0000e0, out 0.0000e0, drop 0.0000e0, punt 0.0000e0 
+                    Name                 State         Calls          Vectors        Suspends         Clocks       Vectors/Call   
+       acl-plugin-fa-cleaner-process   any wait                 0               0              16          1.40e3            0.00 
+       acl-plugin-fa-worker-cleaner-pinterrupt wa               8               0               0          8.97e2            0.00 
+       api-rx-from-ring                 active                  0               0              52          7.12e4            0.00 
+       dpdk-process                    any wait                 0               0               1          1.69e4            0.00 
+       fib-walk                        any wait                 0               0               2          2.55e3            0.00 
+       ip4-reassembly-expire-walk      any wait                 0               0               1          1.27e4            0.00 
+       ip6-icmp-neighbor-discovery-ev  any wait                 0               0               4          1.09e3            0.00 
+       ip6-reassembly-expire-walk      any wait                 0               0               1          2.57e3            0.00 
+       lisp-retry-service              any wait                 0               0               2          1.18e4            0.00 
+       statseg-collector-process       time wait                0               0               1          6.38e3            0.00 
+       unix-epoll-input                 polling              6320               0               0          1.41e6            0.00 
+       vpe-oam-process                 any wait                 0               0               2          7.53e3            0.00 
+
+       Thread 1 vpp_wk_0 (lcore 2) 
+       Time 3.9, average vectors/node 252.74, last 128 main loops 32.00 per node 273.07 
+         vector rates in 7.5833e6, out 7.5833e6, drop 0.0000e0, punt 0.0000e0 
+                    Name                 State         Calls          Vectors        Suspends         Clocks       Vectors/Call   
+       TenGigabitEtherneta/0/0-output   active              58325        14738944               0          9.41e0          252.70 
+       TenGigabitEtherneta/0/0-tx       active              58325        14738944               0          4.32e1          252.70 
+       TenGigabitEtherneta/0/1-output   active              58323        14738944               0          1.02e1          252.71 
+       TenGigabitEtherneta/0/1-tx       active              58323        14738944               0          4.31e1          252.71 
+       acl-plugin-fa-worker-cleaner-pinterrupt wa               8               0               0          1.62e3            0.00 
+       acl-plugin-in-ip4-fa             active             116628        29477888               0          1.01e2          252.75 
+       dpdk-input                       polling             58325        29477888               0          4.63e1          505.41 
+       ethernet-input                   active             116648        29477888               0          1.53e1          252.71 
+       ip4-input-no-checksum            active             116628        29477888               0          3.21e1          252.75 
+       ip4-lookup                       active             116628        29477888               0          2.90e1          252.75 
+       ip4-rewrite                      active             116628        29477888               0          2.48e1          252.75 
+       unix-epoll-input                 polling                57               0               0          2.39e3            0.00  
+                           
+Output/Stateless
+~~~~~~~~~~~~~~~~
+
+Test Case: 64b-1t1c-ethip4udp-ip4base-oacl10sl-10kflows-ndrpdr
+""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+   .. code-block:: console
+
+       DUT1: 
+        Thread 0 vpp_main (lcore 1) 
+        Time 3.8, average vectors/node 0.00, last 128 main loops 0.00 per node 0.00 
+          vector rates in 0.0000e0, out 0.0000e0, drop 0.0000e0, punt 0.0000e0 
+                     Name                 State         Calls          Vectors        Suspends         Clocks       Vectors/Call   
+        acl-plugin-fa-cleaner-process   any wait                 0               0              14          1.43e3            0.00 
+        acl-plugin-fa-worker-cleaner-pinterrupt wa               7               0               0          9.23e2            0.00 
+        api-rx-from-ring                 active                  0               0              52          8.01e4            0.00 
+        dpdk-process                    any wait                 0               0               1          1.59e6            0.00 
+        fib-walk                        any wait                 0               0               2          6.81e3            0.00 
+        ip6-icmp-neighbor-discovery-ev  any wait                 0               0               4          2.81e3            0.00 
+        lisp-retry-service              any wait                 0               0               2          3.64e3            0.00 
+        unix-epoll-input                 polling              4842               0               0          1.81e6            0.00 
+        vpe-oam-process                 any wait                 0               0               1          2.24e4            0.00 
+         
+        Thread 1 vpp_wk_0 (lcore 2) 
+        Time 3.8, average vectors/node 249.29, last 128 main loops 36.00 per node 271.06 
+          vector rates in 5.9196e6, out 5.9196e6, drop 0.0000e0, punt 0.0000e0 
+                     Name                 State         Calls          Vectors        Suspends         Clocks       Vectors/Call   
+        TenGigabitEtherneta/0/0-output   active              45595        11363584               0          9.22e0          249.23 
+        TenGigabitEtherneta/0/0-tx       active              45595        11363584               0          4.25e1          249.23 
+        TenGigabitEtherneta/0/1-output   active              45594        11363584               0          9.75e0          249.23 
+        TenGigabitEtherneta/0/1-tx       active              45594        11363584               0          4.21e1          249.23 
+        acl-plugin-fa-worker-cleaner-pinterrupt wa               7               0               0          1.28e3            0.00 
+        acl-plugin-out-ip4-fa            active              91155        22727168               0          1.78e2          249.32 
+        dpdk-input                       polling             45595        22727168               0          4.64e1          498.46 
+        ethernet-input                   active              91189        22727168               0          1.56e1          249.23 
+        interface-output                 active              91155        22727168               0          1.13e1          249.32 
+        ip4-input-no-checksum            active              91155        22727168               0          1.95e1          249.32 
+        ip4-lookup                       active              91155        22727168               0          2.88e1          249.32 
+        ip4-rewrite                      active              91155        22727168               0          3.53e1          249.32 
+        unix-epoll-input                 polling                44               0               0          1.53e3            0.00 
+                           
+Output/Stateful
+~~~~~~~~~~~~~~~
+
+Test Case: 64b-1t1c-ethip4udp-ip4base-oacl10sf-10kflows-ndrpdr
+""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+.. code-block:: console
+
+       DUT1: 
+        Thread 0 vpp_main (lcore 1) 
+        Time 3.8, average vectors/node 0.00, last 128 main loops 0.00 per node 0.00 
+          vector rates in 0.0000e0, out 0.0000e0, drop 0.0000e0, punt 0.0000e0 
+                     Name                 State         Calls          Vectors        Suspends         Clocks       Vectors/Call   
+        acl-plugin-fa-cleaner-process   any wait                 0               0              16          1.47e3            0.00 
+        acl-plugin-fa-worker-cleaner-pinterrupt wa               8               0               0          8.51e2            0.00 
+        api-rx-from-ring                 active                  0               0              50          7.24e4            0.00 
+        dpdk-process                    any wait                 0               0               2          1.93e4            0.00 
+        fib-walk                        any wait                 0               0               2          2.02e3            0.00 
+        ip4-reassembly-expire-walk      any wait                 0               0               1          3.96e3            0.00 
+        ip6-icmp-neighbor-discovery-ev  any wait                 0               0               4          9.84e2            0.00 
+        ip6-reassembly-expire-walk      any wait                 0               0               1          3.76e3            0.00 
+        lisp-retry-service              any wait                 0               0               2          1.49e4            0.00 
+        statseg-collector-process       time wait                0               0               1          4.98e3            0.00 
+        unix-epoll-input                 polling              5653               0               0          1.55e6            0.00 
+        vpe-oam-process                 any wait                 0               0               2          1.90e3            0.00 
+         
+        Thread 1 vpp_wk_0 (lcore 2) 
+        Time 3.8, average vectors/node 250.85, last 128 main loops 36.00 per node 271.06 
+          vector rates in 7.2686e6, out 7.2686e6, drop 0.0000e0, punt 0.0000e0 
+                     Name                 State         Calls          Vectors        Suspends         Clocks       Vectors/Call   
+        TenGigabitEtherneta/0/0-output   active              55639        13930752               0          9.33e0          250.38 
+        TenGigabitEtherneta/0/0-tx       active              55639        13930752               0          4.27e1          250.38 
+        TenGigabitEtherneta/0/1-output   active              55636        13930758               0          9.81e0          250.39 
+        TenGigabitEtherneta/0/1-tx       active              55636        13930758               0          4.33e1          250.39 
+        acl-plugin-fa-worker-cleaner-pinterrupt wa               8               0               0          1.62e3            0.00 
+        acl-plugin-out-ip4-fa            active             110988        27861510               0          1.04e2          251.03 
+        dpdk-input                       polling             55639        27861510               0          4.62e1          500.76 
+        ethernet-input                   active             111275        27861510               0          1.55e1          250.38 
+        interface-output                 active             110988        27861510               0          1.21e1          251.03 
+        ip4-input-no-checksum            active             110988        27861510               0          1.95e1          251.03 
+        ip4-lookup                       active             110988        27861510               0          2.89e1          251.03 
+        ip4-rewrite                      active             110988        27861510               0          3.55e1          251.03 
+        unix-epoll-input                 polling                54               0               0          2.43e3            0.00  
+                           
+Performance
+-----------
+
++---------------------------------------+-------+-------------------+
+| Test Case                             | MPPS  | Cycles per packet |
++---------------------------------------+-------+-------------------+
+| ethip4-ip4base                        | 18.26 | 136               |
++---------------------------------------+-------+-------------------+
+| ethip4ip4udp-ip4base-iacl1sl-10kflows | 9.134 | 273               |
++---------------------------------------+-------+-------------------+
+| ethip4ip4udp-ip4base-iacl1sf-10kflows | 11.06 | 226               |
++---------------------------------------+-------+-------------------+
+
+Input ACLS (SKX)
+~~~~~~~~~~~~~~~~
+
+.. figure:: /_images/ip4-2n-iacl.png
+
+Output ACLs (HSW)
+~~~~~~~~~~~~~~~~~
+
+.. figure:: /_images/ip4-3n-oacl.png
+
+Configuration
+-------------
+
+Stateful
+~~~~~~~~
+
+.. code-block:: console
+
+       $ sudo vppctl ip_add_del_route 20.20.20.0/24 via 1.1.1.2  sw_if_index 1 resolve-attempts 10 count 1     
+       $ sudo vppctl acl_add_replace  ipv4 permit src 30.30.30.1/32 dst 40.40.40.1/32 sport 1000 dport 1000, ipv4 permit+reflect src 10.10.10.0/24, ipv4 permit+reflect src 20.20.20.0/24        
+       $ sudo vppctl acl_interface_set_acl_list sw_if_index 2 input 0 
+       $ sudo vppctl acl_interface_set_acl_list sw_if_index 1 input 0 
+                           
+Stateless
+~~~~~~~~~
+
+.. code-block:: console
+
+       $ sudo vppctl ip_add_del_route 20.20.20.0/24 via 1.1.1.2  sw_if_index 1 resolve-attempts 10 count 1     
+       $ sudo vppctl acl_add_replace  ipv4 permit src 30.30.30.1/32 dst 40.40.40.1/32 sport 1000 dport 1000, ipv4 permit src 10.10.10.0/24, ipv4 permit src 20.20.20.0/24        
+       $ sudo vppctl acl_interface_set_acl_list sw_if_index 2 input 0 
+       $ sudo vppctl acl_interface_set_acl_list sw_if_index 1 input 0
+              
+Links
+~~~~~
+
+-  `FD.io Security Groups overview <https://wiki.fd.io/view/VPP/SecurityGroups>`__
+-  `Reflexive Access Control Lists <https://packetlife.net/blog/2008/nov/25/reflexive-access-lists/>`__
+-  `Andrew Yuort's Blog on ACLs <http://stdio.be/blog/2017-12-09-Debugging-VPP-MACIP-ACLs/>`__
+
+.. _vppcop:
+
+FD.io VPP COP
+-------------
+
+IPv4/IPv6 white-lists using the FD.io VPP FIB, with support for multiple
+nested white-lists.
+
+Design notes:
+~~~~~~~~~~~~~
+
+- The cop graph nodes (input & white-list) make reuse of the FD.io VPP in FIB 2.0 implementation. Essentially
+  a successful lookup in the FIB, indicates that a packet has been white-listed and may be forwarded.
+
+- cop-input: Determines if the frame is IPv4 or IPv6, and forwards to ipN-copwhitelist graph node.
+
+- ipN-copwhitelist: uses the ip4_fib_[mtrie,lookup] functions to confirm the packet's ip matches a route in the white-list fib.
+
+- Match: if it matches, it is then either sent to the next whitelist or to the ip layer.
+
+- No Match: if it there is not match, it is sent to error-drop.
+
+Operational Data
+~~~~~~~~~~~~~~~~
+
+Note: the double-pass of the ip4-lookup and ip4-rewrite.
+
+.. code-block:: console
+
+    DUT1: 
+     Thread 0 vpp_main (lcore 1) 
+     Time 3.9, average vectors/node 0.00, last 128 main loops 0.00 per node 0.00 
+       vector rates in 0.0000e0, out 0.0000e0, drop 0.0000e0, punt 0.0000e0 
+                  Name                 State         Calls          Vectors        Suspends         Clocks       Vectors/Call   
+     api-rx-from-ring                 active                  0               0              53          4.20e4            0.00 
+     dpdk-process                    any wait                 0               0               1          1.75e4            0.00 
+     fib-walk                        any wait                 0               0               2          1.59e3            0.00 
+     ip4-reassembly-expire-walk      any wait                 0               0               1          2.20e3            0.00 
+     ip6-icmp-neighbor-discovery-ev  any wait                 0               0               4          1.14e3            0.00 
+     ip6-reassembly-expire-walk      any wait                 0               0               1          1.50e3            0.00 
+     lisp-retry-service              any wait                 0               0               2          2.19e3            0.00 
+     statseg-collector-process       time wait                0               0               1          2.48e3            0.00 
+     unix-epoll-input                 polling              2800               0               0          3.15e6            0.00 
+     vpe-oam-process                 any wait                 0               0               2          7.00e2            0.00 
+
+     Thread 1 vpp_wk_0 (lcore 2) 
+     Time 3.9, average vectors/node 220.84, last 128 main loops 20.87 per node 190.86 
+       vector rates in 1.0724e7, out 1.0724e7, drop 0.0000e0, punt 0.0000e0 
+                  Name                 State         Calls          Vectors        Suspends         Clocks       Vectors/Call   
+     TenGigabitEtherneta/0/0-output   active              94960        20698112               0          1.03e1          217.97 
+     TenGigabitEtherneta/0/0-tx       active              94960        20698112               0          3.97e1          217.97 
+     TenGigabitEtherneta/0/1-output   active              92238        20698112               0          9.92e0          224.39 
+     TenGigabitEtherneta/0/1-tx       active              92238        20698112               0          4.26e1          224.39 
+     cop-input                        active              94960        20698112               0          1.98e1          217.97 
+     dpdk-input                       polling             95154        41396224               0          4.58e1          435.04 
+     ethernet-input                   active              92238        20698112               0          1.59e1          224.39 
+     ip4-cop-whitelist                active              94960        20698112               0          3.24e1          217.97 
+     ip4-input                        active              94960        20698112               0          3.13e1          217.97 
+     ip4-input-no-checksum            active              92238        20698112               0          2.23e1          224.39 
+     ip4-lookup                       active             187198        41396224               0          3.08e1          221.14 
+     ip4-rewrite                      active             187198        41396224               0          2.47e1          221.14 
+     unix-epoll-input                 polling                93               0               0          1.35e3            0.00 
+                    
+Performance
+~~~~~~~~~~~
+
++-------------------------------+-------+-------------------+
+| Test Case                     | MPPS  | Cycles per packet |
++-------------------------------+-------+-------------------+
+| ethip4-ip4base                | 18.81 | 132               |
++-------------------------------+-------+-------------------+
+| ethip4-ip4base-copwhtlistbase | 15.12 | 165               |
++-------------------------------+-------+-------------------+
+
+.. figure:: /_images/ip4-acl-features-ndr.png
+
+Configuration
+~~~~~~~~~~~~~
+
+Note: a new VRF 1 is created which holds the whitelist, which then
+applied to the interface 1.
+
+.. code-block:: console
+
+    $ sudo vppctl ip_add_del_route 10.10.10.0/24 via 1.1.1.1  sw_if_index 2 resolve-attempts 10 count 1     
+    $ sudo vppctl ip_table_add_del table 1  
+    $ sudo vppctl ip_add_del_route 20.20.20.0/24  vrf 1  resolve-attempts 10 count 1    local 
+    $ sudo vppctl cop_whitelist_enable_disable sw_if_index 1 ip4 fib-id 1 
+    $ sudo vppctl cop_interface_enable_disable sw_if_index 1  
+                    
+Links
+~~~~~
+
+-  `FIB 2.0: Hierarchical, Protocol Independent. <https://wiki.fd.io/images/7/71/FIB_2.0_-_Hierarchical,_Protocol_Independent..pdf>`__
+
+.. _vppflow:
+
+FD.io VPP Flow
+--------------
+
+FD.io VPP Flow adds the ability for FD.io VPP to support matching of
+flows and taking an associated action. This information is then used to
+program hardware accelerations such as those available on network cards,
+e.g. Intel® Ethernet Flow Director technology on the Intel® Ethernet
+Controller X710/XXV710/XL710.
+
+Supports
+~~~~~~~~
+
+Actions
+"""""""
+
+-  Count: don't now what this does, presume it count's matches.
+-  Mark: Associate a matched flow with arbitrary data such as vxlan tunnel, for a lookup in the redirect graph node.
+-  Buffer Advance: Can be used advance to an encapsulated ethernet or ip header.
+-  Redirect to node: When you see a packet from flow xyz, the next node in FD.io VPP is the indicated graph node.
+-  Redirect to queue: When you see a packet from flow xyz, is to redirect to rx queue n.
+-  Drop: When you see a packet from flow xyz, drop the packet (next node is error drop).
+
+Design Notes
+~~~~~~~~~~~~
+
+-  Currently the only place in FD.io VPP that this is used, is to accelerate VXLAN bypassing the Ethernet and IP Layers.
+-  Flow uses DPDK rte_flow API under the hood for those network interfaces programmed through DPDK.
+-  Redirect to node: worth remember that if you are bypassing a graph, you are bypassing all the checks in the graph node, e.e time-to-live, crcs and the like.
+
+Operational Data
+~~~~~~~~~~~~~~~~
+
+FD.io CSIT numbers for VXLan do not use FD.io Flow support.
+
+Performance
+~~~~~~~~~~~
+
+FD.io CSIT numbers for VXLan do not use FD.io Flow support.
+
+Configuration
+~~~~~~~~~~~~~
+
+-  `Flow API <https://git.fd.io/vpp/tree/src/vnet/flow/flow.h>`__
+
+.. _classifiers:
+
+FD.io VPP Classifiers
+---------------------
+
+The most flexible form of ACLs in FD.io VPP enable the user to match anywhere in the first
+80 bytes of the packet header.
+
+Configuration
+~~~~~~~~~~~~~
+
+Match an IPv6….
+
+.. code-block:: console
+
+    $ sudo vppctl classify table mask l3 ip6 dst buckets 64
+    $ sudo vppctl classify session hit-next 0 table-index 0 match l3 ip6 dst 2001:db8:1::2 opaque-index 42
+    $ sudo vppctl set interface l2 input classify intfc host-s0_s1 ip6-table 0
+                           
+Links
+~~~~~
+
+-  `Overview of classifers <https://wiki.fd.io/view/VPP/SecurityGroups#Existing_functionality>`__
+-  `FD.io VPP Classifiers Overview <https://wiki.fd.io/view/VPP/Introduction_To_N-tuple_Classifiers>`__
+-  `FD.io VPP Classifiers CLI <https://docs.fd.io/vpp/19.04/clicmd_src_vnet_classify.html>`__
+-  `Sample Code from Andrew Yourt <http://stdio.be/vpp/t/aytest-bridge-tap-py.txt>`__
diff --git a/docs/usecases/index.rst b/docs/usecases/index.rst
index 94135ea472f..3bcc129f6ae 100644
--- a/docs/usecases/index.rst
+++ b/docs/usecases/index.rst
@@ -13,6 +13,7 @@ extensive list, but should give a sampling of the many features contained in FD.
    simpleperf/index.rst
    vhost/index.rst
    vmxnet3
+   acls
    vppcloud
    homegateway
    contiv/index.rst