Add basic MPLS testcases

[SijiJ]

Description of PR

Summary: To add basic MPLS testcases to sonic-mgmt/tests

The PR adds basic label forwarding tests involving push, swap, pop operatios.
Fixes # (issue)

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• [ x] Test case(new)

Approach

What is the motivation for this PR?

As part of qualification of new MPLS feature added.

How did you do it?

Added MPLS feature testcases on t1 Pytest testbed.

How did you verify/test it?

Verified it on t1 testbed. All three MPLS label action ,push, pop and swap.

Any platform specific information?

Verified on Juniper PTX10008, it would work on any platform with MPLS SAI support.

Supported testbed topology if it's a new test case?

T1

Documentation

https://github.com/SijiJ/sonic-mgmt/blob/master/docs/testplan/MPLS-test-plan.md

[ghost]

All CLA requirements met.

[yxieca]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[smaheshm]

One concern is hardcoding values in json file, e.g. Nexthop IP, interface names etc. It will be better if these files can be generated by getting the interface names and nexthops at run time.

[smaheshm]

I understand the scope is MPLS basic forwarding. In addition to the tests you already listed, I think more can be added for basic MPLS forwarding tests. For e.g following test cases should be added for label forwarding tests. Feel free to add more.

POP - multi label, only top label should be poppped

NHOP ECMP:

• Multiple label next hops
• Multiple label and IP next hops

LABEL ECMP

• Load balancing for label, (src/dst IP remains same, change label)
• Mupltiple labels. Verify ECMP, change the outermost label

LABEL ECMP - port flap

• bring down a port - check load balancing
• bring up the port - check load balancing

MPLS QoS

• Verify QoS mapping between IP and MPLS at ingress
• Verify QoS mapping between IP and MPLS at egress

MAX Labels test

• pick 4 labels as MAX, push labels and verify forwarding

Negative test case:

• Send MPLS traffic on i/f with no MPLS enabled - traffic must be dropped

[lgtm-com]

This pull request introduces 1 alert when merging a101ed0 into 5fecae8 - view on LGTM.com

new alerts:

• 1 for Unused local variable

[zhangyanzhao]

@wangxin would you please help to approve if you are ok with the change? Thanks.

[zhangyanzhao]

@SijiJ would you please to address all the comments to move forward? This is blocking the 202111 final delivery. Thanks.

[SijiJ]

@SijiJ would you please to address all the comments to move forward? This is blocking the 202111 final delivery. Thanks.

Moved all review comments to resolved.

[wangxin]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).