100GE DAC cable (QSFP-100G-CU1M) connection between NCS55A2-MOD and Cat9K stays down

[filopeter]

Hello,

I need to connect NCS55A2-MOD (MPA NC55-MPA-4H-S) with Catalyst C9500-48Y4C using the DAC cable. Although this cable is supported by both devices, the connection remains down on physical level.

Based on the missing autonegotiation support on Cat9K (bug id CSCvk07538), I have tried to disable it on NCS using the following command

!
RP/0/RP0/CPU0:router(config)# interface HundredGigE 0/0/1/2
RP/0/RP0/CPU0:router(config-if)# no negotiation auto
!

but it does not help.

Any ideas how to bring the connection up and running?

Best Regards,

Peter

[tkarnani]

I have seen a few issues with auto negotiation and that particular cable. what version are you running?

have you tried negotiation auto on both sides ?

[filopeter]

I have tested 6.5.3, 6.6.3 and 7.0.2 version on NCS55A2, always with the same result.

According the NCS interface config guide,  the default setting for auto-negotiation varies with different platforms under the NCS 5500 family. On NCS 540 and NCS 55A2, 100G auto-negotiation is enabled by default.

I hope it can be turned off, the command is there but I do not know if it works.

The opposite device is Catalyst 9500, which, according the bug mentioned in the original message,  does not support auto negotiation on 100GE ports.

It looks like an interoperability issue, because 100GE connection between two NCSes using the DAC cable works, also 100GE connection over DAC cable is up between the Catalyst switches, it just does not work between the NCS and Catalyst switch.

Best Regards,

P.