[202503] Add fec: rs to port config for ports with >=50G per lane#2007
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sdszhang wants to merge 1 commit intoAzure:202503from
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[202503] Add fec: rs to port config for ports with >=50G per lane#2007sdszhang wants to merge 1 commit intoAzure:202503from
sdszhang wants to merge 1 commit intoAzure:202503from
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Why I did it Ports with lane speed >=50G use PAM4 modulation and should indicate "fec": "rs" in the port config. This fixes issue Enhancement:FEC not configured for PAM4 speeds #23561 #### Why I did it Ports with lane speed >=50G use PAM4 modulation and should indicate "fec": "rs" in the port config. Without this, the FEC configuration is missing for PAM4 speeds, which can lead to link stability issues. ##### Work item tracking - Microsoft ADO **(number only)**: #### How I did it Modified `portconfig.py` to automatically set `"fec": "rs"` for ports where the lane speed is >=50G (PAM4 modulation). Updated the logic to detect lane speed based on port speed and number of lanes, and apply the appropriate FEC configuration. #### How to verify it 1. Generate port configuration for platforms with ports using >=50G per lane (e.g., 400G ports with 8 lanes, 200G ports with 4 lanes) 2. Verify that the generated config includes `"fec": "rs"` for these ports 3. Run the updated unit tests: `test_cfggen_platformJson.py` #### Which release branch to backport (provide reason below if selected) - [ ] 201811 - [ ] 201911 - [ ] 202006 - [ ] 202012 - [ ] 202106 - [ ] 202111 - [ ] 202205 - [ ] 202211 #### Tested branch (Please provide the tested image version) - [x] 202412 branch #### Description for the changelog Add automatic FEC RS configuration for ports with lane speed >=50G (PAM4 modulation) <!-- Ensure to add label/tag for the feature raised. example - PR#2174 under sonic-utilities repo. where, Generic Config and Update feature has been labelled as GCU. --> #### Link to config_db schema for YANG module changes <!-- Provide a link to config_db schema for the table for which YANG model is defined Link should point to correct section on https://github.com/Azure/sonic-buildimage/blob/master/src/sonic-yang-models/doc/Configuration.md --> #### A picture of a cute animal (not mandatory but encouraged)
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original PR #1950 and |
prgeor
approved these changes
Feb 21, 2026
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cherry-pick #1950 to 202503.
Why I did it
Ports with lane speed >=50G use PAM4 modulation and should indicate "fec": "rs" in the port config.
Work item tracking
How I did it
Check the lane speed and add "fec": "rs" for lanes with speed at least 50G.
How to verify it
sonic-cfggen -k <device-name> --print-data | grep Ethernet0 -C 10Make sure that fec rs is there by default if it's a PAM4 speed. Otherwise don’t insert anything To verify whether “fec”: “rs” is only being added for lane speeds above 50G, we used these 3 test inputs and show their respective outputs. Test Input 1:Should have fec because the lane speed is greater than 50G. Output:
Test Input 2:
Should not have fec because the lane speed is less than 50G. Output:
Test Input 3:
Should have fec because lane speed is 50G. Output:
Which release branch to backport (provide reason below if selected)
Tested branch (Please provide the tested image version)
Description for the changelog
Link to config_db schema for YANG module changes
A picture of a cute animal (not mandatory but encouraged)