Support kube-proxy data plane

This plugin provides kube-proxy data plane on user space,
which is used to replace linux kernal's kube-proxy based on iptables.
The idea is largely inspired from VPP LB plugin.

Currently, kube-proxy plugin supports three service types:
1) Cluster IP plus Port: support any protocols, including TCP, UDP.
2) Node IP plus Node Port: currently only support UDP.
3) External Load Balancer.

Please refer to kp_plugin_doc.md for details.

Change-Id: I36690e417dd26ad5ec1bd77c7ea4b8100416cac6
Signed-off-by: Hongjun Ni <hongjun.ni@intel.com>

1 files changed, 105 insertions, 0 deletions

diff --git a/src/plugins/kubeproxy/kp_plugin_doc.md b/src/plugins/kubeproxy/kp_plugin_doc.md
new file mode 100644
index 00000000000..e1247916bd5
--- /dev/null
+++ b/src/plugins/kubeproxy/kp_plugin_doc.md
@@ -0,0 +1,105 @@
+# Kube-proxy plugin for VPP
+
+## Overview
+
+This plugin provides kube-proxy data plane on user space,
+which is used to replace linux kernal's kube-proxy based on iptables.
+The idea is largely inspired from VPP LB plugin.
+
+Currently, kube-proxy plugin supports three service types:
+1) Cluster IP plus Port: support any protocols, including TCP, UDP.
+2) Node IP plus Node Port: currently only support UDP.
+3) External Load Balancer.
+
+For Cluster IP plus Port case:
+kube-proxy is configured with a set of Virtual IPs (VIP, which can be
+prefixes), and for each VIP, with a set of POD addresses (PODs).
+
+For a specific session received for a given VIP (or VIP prefix), 
+first packet selects a Pod according to internal load balancing algorithm, 
+then does DNAT operation and sent to chosen Pod.
+At the same time, will create a session entry to store Pod chosen result.
+Following packets for that session will look up session table first, 
+which ensures that a given session will always be routed to the same Pod.
+
+For returned packet from Pod, it will do SNAT operation and sent out.
+
+Please refer to below for details: 
+https://schd.ws/hosted_files/ossna2017/1e/VPP_K8S_GTPU_OSSNA.pdf
+
+
+## Configuration
+
+### Global KP parameters
+
+The kube-proxy needs to be configured with some parameters:
+
+	ku conf [buckets <n>] [timeout <s>]
+
+buckets: the *per-thread* established-connections-table number of buckets.
+
+timeout: the number of seconds a connection will remain in the
+         established-connections-table while no packet for this flow
+         is received.
+
+### Configure VIPs and Ports
+
+    ku vip <prefix>  port <n> target_port <n> node_port <n> \
+      [nat4|nat6)] [new_len <n>] [del]
+
+new_len is the size of the new-connection-table. It should be 1 or 2 orders of
+magnitude bigger than the number of PODs for the VIP in order to ensure a good
+load balancing.
+
+Examples:
+
+    ku vip 90.0.0.0/8 nat44 new_len 2048
+    ku vip 2003::/16 nat66 new_len 2048
+    
+### Configure PODs (for each VIP)
+
+    ku pod <vip-prefix> [<address> [<address> [...]]] [del]
+
+You can add (or delete) as many PODs at a time (for a single VIP).
+
+Examples:
+
+    ku pod 90.0.0.0/8 10.0.0.1
+    ku pod 2002::/16 2001::2 2001::3 2001::4
+
+### Configure SNAT
+
+    ku set interface nat4 in <intfc> [del]
+
+Set SNAT feature in a specific interface.
+
+
+## Monitoring
+
+The plugin provides quite a bunch of counters and information.
+
+    show ku
+    show ku vip verbose
+    show node counters
+
+
+## Design notes
+
+### Multi-Threading
+
+This implementation implement parallelism by using 
+one established-connections table per thread. This is equivalent to assuming
+that RSS will make a job similar to ECMP, and is pretty useful as threads don't
+need to get a lock in order to write in the table.
+
+### Hash Table
+
+A kube-proxy requires an efficient read and write Hash table. The Hash table
+used by ip6-forward is very read-efficient, but not so much for writing. In
+addition, it is not a big deal if writing into the Hash table fails.
+
+The plugin therefore uses a very specific Hash table.
+	- Fixed (and power of 2) number of buckets (configured at runtime)
+	- Fixed (and power of 2) elements per buckets (configured at compilation time)
+
+