Supported Link modes - Unable to set Speed

I am unable to set speed of a switch. I could see that the supported modes of port is 10000

cumulus@cumulus:~$ sudo ethtool xxx
Settings for swp8s3:
Supported ports: [ FIBRE ]
Supported link modes: 10000baseT/Full
Supported pause frame use: Symmetric Receive-only
Supports auto-negotiation: Yes
Advertised link modes: Not reported
Advertised pause frame use: No
Advertised auto-negotiation: No
Speed: 10000Mb/s
Duplex: Full
Transceiver: internal
Auto-negotiation: off
Link detected: yes

When I try to execute the command

ethtool -s swp8s2 speed 1000 duplex full

it throws error,
Cannot set new settings: Operation not supported
not setting speed
not setting duplex

Is it because its not in the "Supported link modes"?

1 reply

Hi Nivas. Yes, that is correct. the supported speed interpreted for the module is 10,000 and you are trying to do 1,000.

It is possible to get 1G over a 4x10G breakout scenario, but it requires modules that support it and it may require a CL version change.
What is your use case and what module/cable do you have installed? Also what switch hardware and CL version are you running?

It may be a good idea to open a support case to sort out the particulars of your scenario.