Docs: readme files of dmm-lwip

Change-Id: I0c4651a3db5b1eda86cf322f5ca32b32796dad01
Signed-off-by: Swarup Nayak <swarupnpvt@gmail.com>

2 files changed, 120 insertions, 0 deletions

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+# 1. What is lwIP
+lwIP is a light-weight implementation of the TCP/IP protocol suite.
+lwIP is freely available (under a BSD-style license) in C source
+code format and can be downloaded from the development homepage.
+The focus of the lwIP TCP/IP implementation is to reduce the RAM
+usage while still having a full scale TCP.
+
+# 2. How to use lwIP
+
+## How to integrate lwIP into DMM
+The file CMakeList.txt defined the compiling process, including downloading
+the lwip 2.7.0 code and pushing the helper files into it, or modify
+lwip files.
+
+Currently lwip will not be build as separate lib, instead it'll be part
+of the excutable namely "nStackMain".
+lwip Stack will run in pipeline mode. Application will run in one process
+and lwip will run as "nStackMain" process. Below picture depicts
+a birds eye view of lwip in DMM pipeline mode.
+![Lwip in DMM framework](dmm_lwip.png)
+
+## Compile
+```sh
+    #cd dmm/build && cmake ..
+    #make
+    #cd ../stacks/lwip_stack/build && cmake ..
+    #make
+```
+
+## Test
+- Steps 1: update some environment variables
+```sh
+	#export LD_LIBRARY_PATH=${dmm}/stacks/lwip_stack/release/lib64/
+	#export LD_PRELOAD=${dmm}/release/lib64/libnStackAPI.so
+	#export NSTACK_MOD_CFG_FILE=${dmm}/stacks/lwip_stack/app_conf/module_config.json
+	#export NSTACK_MOD_CFG_RD=${dmm}/stacks/lwip_stack/app_conf/rd_config.json
+	#export NSTACK_LOG_ON=DBG  (optional enable debug)
+```
+- Steps 2: Modify rd_config.json(located at dmm/stacks/lwip_stack/app_config/)
+```sh
+	#vim rd_config.json
+	  Eg. set "subnet": "192.168.21.1/24"
+```
+Note:
+  Means dmm chose lwip_stack if subnet matches 192.168.21.*
+
+- Steps 3: 	Run nStackMain(lwip stack))
+```sh
+	#cp ${dmm}/stacks/lwip_stack/release/configure/ip_data.json  ${dmm}/stacks/lwip_stack/release/bin/
+	#cp ${dmm}/stacks/lwip_stack/release/configure/network_data_tonStack.json  ${dmm}/stacks/lwip_stack/release/bin/
+
+```
+Modify ip_data.json
+```
+Change ref_nic => to interface name which you want to use
+Change ip_cidr => ip address you want to use.
+```
+Modify network network_data_tonStack.json
+```
+Change ref_nic => to interface name which you want to use
+Change subnet => Subnet (ip_cidr belongs to this subnet)
+Change gateway, range-start, range-end, dst, gw accordingly. This information will be used by DMM to configure network.
+```
+Run the process:
+```
+	#cd ${dmm}/stacks/lwip_stack/release
+	#./start_nstack.sh
+```
+
+- Steps 4: Communication test between machine A(as server) with machine B
+		(as client)
+
+##### Run in machine A
+```sh
+	#./dmm/release/bin/vs_epoll -p 20000 -d 192.168.21.180 -a 10000 -s 192.168.21.181 -l 1000 -t 500000 -i 0 -f 1 -r 20000 -n 1 -w 10 -u 50000 -e 10 -x 1
+```
+Note:
+  Means the current machine would be server, and it's
+destination address is 192.168.21.180 (client address),
+source address is 192.168.21.181(server address)
+
+##### Run in machine B
+```
+	#./dmm/release/bin/vc_common -p 20000 -d 192.168.21.181 -a 10000 -s 192.168.21.180 -l 1000 -t 500000 -i 0 -f 1 -r 20000 -n 1 -w 10 -u 50000 -e 10 -x 1
+```
+Note:
+  Means the current machine would be client, and it's
+destination address is 192.168.21.181 (server address),
+source address is 192.168.21.180(client address)
+
+# 3. Document description
+
+(dmm/stacks/lwip_stack/doc)
+
+## CMakeLists.txt
+Control file for Cmake compiling.
+
+## config folder
+##### module_config.json
+- module_config.json is for configuring dmm protocol stack module.
+
+##### rd_config.json
+- rd_config.json is to choose which module is better to go through, if subnet matches, It will go through lwip protocol stack when RD type is nstack-dpdk
+
+## lwip helper files.
+lwip helper files is implmentation and modification of some supportive functions to run lwip with dmm.
+
+## lwip_stack/src folder
+
+- Implmetation of nStackMain process which provides the framework to hold lwip stack.
+
+## lwip_stack/lwip_src
+- Downloaded opensource lwip 2.7.0. code.
+
+# 4. More Information
+https://wiki.fd.io/view/DMM
+https://savannah.nongnu.org/projects/lwip/
+http://lwip.wikia.com/wiki/LwIP_Wiki
+[DMM_DeveloperManual.md](../../doc/DMM_DeveloperManual.md)
+
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