[BFD] Test improvements and fixes

[ihorchekh]

Description of PR

Summary: Improved BFD test. Fixed test issues. Added logging and docstrings.
Fixes # (issue)

Type of change

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

Back port request

• 201911
• 202012

Approach

What is the motivation for this PR?

To improve the test

How did you do it?

How did you verify/test it?

Ran on 202012 and 202205 images

Any platform specific information?

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

't1', 't1-lag', 't1-64-lag'

Documentation

[lgtm-com]

This pull request fixes 3 alerts when merging 13b2836 into 63fb8f6 - view on LGTM.com

fixed alerts:

• 3 for Unused import

[siqbal1986]

Can you please tell me how you were able to scale the number to 500. In my test environment, the bfdd starts to fail if I create more than 128 sessions. Also, I noticed you are creating each session individually by making a call to PTF for each session. Can you give me an idea how long does this take to run through?

[ihorchekh]

Can you please tell me how you were able to scale the number to 500. In my test environment, the bfdd starts to fail if I create more than 128 sessions.

I did a few tests runs on IPv4 scaled test. 400 sessions passed, 600 failed, 500 passed, and 600 failed again. So, I've assumed that 500 is a working amount. But for IPv6 scaled test I agree with you, the bfdd-control started to flap after 128 sessions. Can you run IPv4 with 500 sessions on your end in order to confirm it?

Also, I noticed you are creating each session individually by making a call to PTF for each session. Can you give me an idea how long does this take to run through?

Could you point me to where did you see it? In the create_ptf_bfd_sessions it creates sessions in batch by 100 commands.

[lgtm-com]

This pull request fixes 3 alerts when merging 9596852 into f7ea483 - view on LGTM.com

fixed alerts:

• 3 for Unused import