Bringing up a 25Gbps interface on Nexus 93108YC-EX

[c.walsh]

I have a N9K-C93180YC-EX & i am trying to bring up a connection to a C9500-24Y4C switch.

Tested connection with 10Gbps SFP's no problem, but when using a pair of SFP-10/25G-CSR-S SFP's & can't get the link to come up.  I have tested the fibre patch lead & both SFP-10/25G-CSR-S SFP's between a pair of C9500-24Y4C switches.

There is no option to set the interface speed to 25Gbps on the Nexus, am i missing some interface configuration?

Thanks in advance

Colin

[Andrea Testino · Accepted solution]

Hi Colin,

A couple of clarification questions:

1 - Are you saying when you connect the 10/25G SFP between a pair of C9500-24YC4C, the links do come up/up?

2 - What version of NXOS is the 93108YC-EX running versus the C9500? (minimum would be 9.2(1) for that specific's SFP support)

3- Have you tried configuring "negotiate auto 25000" on both sides of the 25G link b/w the two Nexus?

Page 58-59 here https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/93x/interfaces/configuration/guide/b-cisco-nexus-9000-nx-os-interfaces-configuration-guide-93x.pdf

[c.walsh]

Hi Andrea,

      We are using version 7.0(3) as that is the suggested version on CCO.

Will upgrade & test.

thanks

Colin

[c.walsh]

Hi Andrea,

    Upgraded Nexus to version 9.3.5, but the interface would still not come up. 

Had the change the FEC mode on each switch to bring up both sides.

On Nexus...

interface Ethernet1/1
switchport mode trunk
mtu 9100
fec fc-fec
channel-group 1 mode active
no shutdown

On Catalyst 9500...

interface TwentyFiveGigE1/0/1
switchport mode trunk
mtu 9100
speed 25000
fec cl74
channel-group 1 mode active