Added new test plans for VNET to VNET testing (#297)

* Added new test plans for VNET to VNET testing

* Incorporated changes recommended

* Updated link to SONiC test plan template

The recommendation was to de-duplicate the SONiC test plan template and referenced it to its original placeholder

* Deleting the SONiC test plan template

Removing the test plan template as the link to it is provided in the README file

* Linked to the original VNET-to-VNET-service doc

Removed the diagram and referenced to the original VNET service document under DASH documentation

* Removed vm-to-vm-communication-vnet.svg

Since the original document is reference, no need for the VM to VM communication svg file here

* Fixed the VNET service link

rectified the incorrect VNET service link to reflect the correct one

* Fixed typos

Rectified some typos in the document

* Fixed the image in Test plan document

test/docs/README.md

@@ -14,3 +14,6 @@
 | [SAI Challenger DASH Schema](README-SAIC-DASH-config-spec.md) | High-level schema to generate scaled configurations (e.g. via [dpugen](https://pypi.org/project/dpugen/)) as well as the DASH "SAI Record" format which comprises SAI "CRUD" operations.
 | [SAI Challenger Tutorials](../test-cases/functional/saic/tutorial/README.md) | Guided tour of SAI Challenger for DASH
 | [SAI Challenger Test Workflows](dash-test-sai-challenger.md) | How to run scalable tests using SAI-Challenger and snappi. |
+| [Testbed](testbed/README.md) | Describes the setup and configuration of a DASH testbed.|
+| [snappi and SAI-Challenger based tests](dash-test-sai-challenger.md) | How to run scalable tests using SAI-Challenger and snappi. The scalability is achieved with additional DASH/SAI abstraction level in test code to simplify high scale DUT configuration. |
+| [Test Plans](testplans/README.md) |  Home of DASH features test plans including test plan template |

test/docs/testplans/README.md

@@ -0,0 +1,11 @@
+# DASH Test Plans
+
+In this document you will see a summary of the test plans available for DASH testing.
+
+A test plan template is available [here](https://github.com/sonic-net/SONiC/blob/master/doc/SONiC%20Test%20Plan%20Template.md) for reference.
+
+
+| Test Plan | Description |
+|----------|-------------|
+| [ACL](acl.md) | Access control list test plan|  
+| [VNET to VNET](vnet_to_vnet.md) | Describes test plan for testing the mechanisms of VM to VM communication in VNET|

test/docs/testplans/vnet_to_vnet.md

@@ -0,0 +1,60 @@
+# **VNET to VNET**
+
+## Overview
+
+This test plan corresponds to the phase where standardized, automated test cases 
+will be scripted to verify Data plane Testing Stage 3 as outlined in [dash test maturity stages](../dash-test-maturity-stages.md#data-plane-testing-stage-3-dut-configuration-via-sai-thrift). 
+
+In these tests we want to leverage the snappi API to test some of the functional aspects of DUT. 
+By verifying and validating the scaling aspects of the switches (hardware/BMv2) 
+we are able to empirically baseline the scaling values. Additionally, we also 
+want to check some of the relevant counters to features like IPv4, IPv6, TCP, 
+UDP, common traffic stats etc.
+
+### Scope
+
+These test cases are targeted for testing the feature functionality of DASH implementation. The purpose of these test cases are to verify inbound/outbound/bidirectional traffic streams originating and terminating at the traffic generator. We plan to use the [OTG](https://github.com/open-traffic-generator) (Open traffic generator model) by leveraging the snappi APIs. 
+
+### Testbed
+
+The generic testbed setup may consist of two OTG connected to two ports of a switch (hardware-based or BMv2 software switch). 
+In this specific testbed setup we will use [Ixia-c](https://github.com/open-traffic-generator/ixia-c) which is a modern, powerful, and API-driven open traffic generator model-based traffic tool that will generate traffic to observe the behavior of the device under test (DUT).
+
+### Testbed Topology 
+
+The testbed is setup to emulate a VNET to VNET scenario and to test the mechanisms of VM to VM communication in VNET as outlined [here](https://github.com/Azure/DASH/blob/main/documentation/vnet2vnet-service/vnet-to-vnet-service.md).
+
+
+
+To emulate each VM in a VNET an Ixia-c port will be utilized. The BMv2 will be the DUT (This can later be replaced by a hardware-based appliance that connects to physical ports of a traffic generator)
+
+![ixia-c.DUT](../../images/ixia-c.dut.svg)
+
+In the above diagram:
+- Ixia-C can be replaced by a hardware-based OTG
+- BMv2 switch can be replaced with another software-based or a hardware-based switch
+
+### Test Methodology
+
+Following test methodologies will be utilized to verify and validate the behavior of the switch
+
+- Traffic generator will be used to configure traffic streams that originate and/or terminate on traffic generator ports
+- Data traffic will be sent from VNET to VNET to verify performance properties like: CPS, flow, PPS, and rule scale.  These performance properties will be verified while  features like: VM to VM communication in VNET, route support, LPM support, ACL support are enabled.
+- Depending on the test cases, a combination of UDP traffic for IPv4, IPv6 addresses will be generated
+
+### Test Cases
+Note: No counters exist to date. Once counters are defined, the test-cases will be refined to incorporate them.
+
+| Test Description                                             | Expected Result               |
+| :----------------------------------------------------------- | :------------------------ |
+| UDP IPv4 inbound  | Verify traffic originating from one VNET simulated terminates on another simulated VNET. <br><br> Verify counters in DUT in the inbound direction are accurately incremented. <br><br> Verify latency measurements <br> Verify packet loss is 0 (Tx frames - Rx frames = 0) <br><br> Verify configured throughput rate is achieved in traffic statistics  |
+| UDP IPv4 outbound | Verify traffic originating from one VNET simulated terminates on another simulated VNET. <br><br> Verify counters in DUT in the inbound direction are accurately incremented. <br><br> Verify latency measurements <br> Verify packet loss is 0 (Tx frames - Rx frames = 0) <br><br> Verify configured throughput rate is achieved in traffic statistics |
+| UDP IPv4 bidirectional  | Verify traffic originating from one VNET simulated terminates on another simulated VNET. <br><br> Verify counters in DUT in the inbound direction are accurately incremented. <br><br> Verify latency measurements <br> Verify packet loss is 0 (Tx frames - Rx frames = 0) <br><br> Verify configured throughput rate is achieved in traffic statistics    |
+| UDP IPv6 inbound | Verify traffic originating from one VNET simulated terminates on another simulated VNET. <br><br> Verify counters in DUT in the inbound direction are accurately incremented. <br><br> Verify latency measurements <br> Verify packet loss is 0 (Tx frames - Rx frames = 0) <br><br> Verify configured throughput rate is achieved in traffic statistics    |
+| UDP IPv6 outbound direction | Verify traffic originating from one VNET simulated terminates on another simulated VNET. <br><br> Verify counters in DUT in the inbound direction are accurately incremented. <br><br> Verify latency measurements <br> Verify packet loss is 0 (Tx frames - Rx frames = 0) <br><br> Verify configured throughput rate is achieved in traffic statistics  |
+| UDP IPv6 bidirectional  | Verify traffic originating from one VNET simulated terminates on another simulated VNET. <br><br> Verify counters in DUT in the inbound direction are accurately incremented. <br><br> Verify latency measurements <br> Verify packet loss is 0 (Tx frames - Rx frames = 0) <br><br> Verify configured throughput rate is achieved in traffic statistics  |                                                 
+|  ACL inbound | Verify data traffic is allowed and unwanted traffic based on ACL is dropped. <br><br>Verify ACL inbound counters on DUT are incremented
+| ACL outbound  | Verify data traffic is allowed and unwanted traffic based on ACL is dropped. <br><br>Verify ACL outbound counters on DUT are incremented
+| BGP underlay | Verify BGP adjacency is established. <br><br>Verify BGP counters on DUT are incremented
+
+