Problems with 1000BaseSX SFP and "speed nonegotiate"

[vesk01]

Hello guys,

I have a question about a very particular situation and I need your ideas and hints how to solve the problem.

The situation is like that. I have two devices: a Cisco ME-3600X and a Cisco WS-C3560. The C3560 is a service provider device and I cannot change anything there.

There is a link between these devices which is connecting a TenGigabitEthernet port with 1000BaseSX SFP on the 3600X side (my side) with a GigabitEthernet port with 1000BaseSX SFP on the C3560 side (Service Provider side).

The SP side is configured with "speed nonegotiate" under the GigabitEthernet interface and unfortunately this setting must stay like that.

If I configure the same "speed nonegotiate" under my TenGigabitEthernet port with 1000BaseSX SFP it switches to 1G but still the link doesn't come up. If both the sides switch to auto negotiation then the link comes up (tested in a lab environment), but unfortunately the SP will not change to auto, so the "speed nonegotiate" must stay on their side and I must configure somehow my side to be able to build up a conneciton.

Any suggestions?

Thanks in advance,

Vesko

[rsimoni · Accepted solution]

Hi Vesko,

unfortunately there is no solution for you if your SP does not want to collaborate.

This is a known issue documented on a bug:

CSCtt42712    link is not up if 1G SFP inserted in 10G slot with speed nonegotiate

Release-note:

Symptom:

ME3600x failed to get the 10G port UP when inserting a 1G SFP on 12.2(52)EY2

Conditions:

This happens when config the "speed nonegotiate" on the 10G SFP+ port and insert a supported 1G SFP

Workaround:

Use speed auto on both side.

=========

There is no other workaround as the command 'nonegotiate' is not supported (it has nothing to do with the particular software release mentioned above but applies to the platform).

This is also documented in the configuration guide:

"•The nonegotiate keyword is available but is not supported. When a Cisco1000BASE-T SFP module is in the SFP module slot, the speed can be configured to 10, 100, 1000, or to auto, but not to nonegotiate."

http://www.cisco.com/en/US/docs/switches/metro/me3600x_3800x/software/release/15.1_2_ey/configuration/guide/swint.html#wp1028628

I think you have to go down on your knees and beg your SP to change their setting

or else don't use the tengiga link but a giga one.

please rate and close the question if helpful.

BR,

Riccardo

[vesk01]

Hello Riccardo,

thank you very much for the detailed answer!

Vesko