[action] [PR:24521] [topo] Add t1-isolated-d32u1s2 topology

[mssonicbld]

Description of PR

Summary:
Add a new topology t1-isolated-d32u1s2, a reduced version of t1-isolated-d508u1s2 with 32 T0 downlinks (instead of 508) plus the same 1 T2 uplink and 2 PT1 peers. Useful for scaled-down testbeds that still exercise the d508u1s2 layout shape without requiring 508 downlink VMs.

Reduction rule applied to the 508 downlink panel ports (0..507): keep only the 1st and 25th port of every 32-port block (panel ports where p % 32 in {0, 24}). Uplink (508) and peer ports (509, 510) are unchanged.

Fixes # (n/a)

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• New Test case
• Skipped for non-supported platforms
• Test case improvement

Back port request

• 202205
• 202305
• 202311
• 202405
• 202411
• 202505
• 202511

Approach

What is the motivation for this PR?

We need a reduced t1-isolated topology that mirrors the structure of t1-isolated-d508u1s2 but uses far fewer downlink VMs, so it can be brought up on smaller testbeds while still being representative of the d508u1s2 shape (same uplink, same peer pair, IP/VLAN assignments aligned with the surviving subset of the d508 layout).

How did you do it?

• Added a new 'd32u1s2' entry to hw_port_cfg in ansible/generate_topo.py that reuses the d508u1s2 uplink/peer setup and skips all downlink panel ports outside the {0, 24} mod-32 selection:

'd32u1s2': {"ds_breakout": 1, "us_breakout": 1, "ds_link_step": 1, "us_link_step": 1,
"uplink_ports": [508],
"peer_ports": [509, 510],
"skip_ports": [p for p in range(508) if p % 32 not in (0, 24)],
"panel_port_step": 1},

• Regenerated the topology file with:

./generate_topo.py -r t1 -k isolated -t t1-isolated -c 509 -l 'd32u1s2'

• Added the example invocation to the main() docstring next to the existing d508u1s2 example.

How did you verify/test it?

• Ran the generator command above and confirmed vars/topo_t1-isolated-d32u1s2.yml is produced (889 lines, 35 VMs total: 32 T0 + 1 T2 + 2 PT1).
• Verified VM names follow the existing convention (ARISTA01T0, ARISTA25T0, ARISTA33T0, ..., ARISTA481T0, ARISTA505T0).
• Spot-checked that VLAN/IP assignments for the surviving downlink VMs match their counterparts in topo_t1-isolated-d508u1s2.yml (e.g. ARISTA25T0 keeps 10.0.0.49 / fc00::62 / 100.1.0.25), and that the T2/PT1 sections (ARISTA01T2, ARISTA01PT1, ARISTA02PT1) are byte-identical to the d508 file.

Any platform specific information?

N/A — generator/topology change only.

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

N/A — not a new test case; this adds a new testbed topology variant.

Documentation

N/A

[mssonicbld]

Original PR: #24521

[mssonicbld]

/azp run

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[mssonicbld]

/azp run

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Azure Pipelines successfully started running 1 pipeline(s).

[mssonicbld]

This cherry pick PR has been opened for more than 3 days. The mssonicbld will attempt to retry.

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[mssonicbld]

/azpw retry

[mssonicbld]

Retrying failed(or canceled) jobs...

[mssonicbld]

Retrying failed(or canceled) stages in build 1117439:

✅Stage Test:

• Job impacted-area-kvmtest-t0 by Elastictest: retried.

[mssonicbld]

@vmittal-msft The cherry pick PR didn't pass PR checker after retry. Left a comment in original PR #24521 to notify author.

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