C9500-12Q connecting to C2960X with GLC-SX-MM

[rlcole]

Hi,

I have a C9500-12Q-E that I'm trying to connect to a C2960X-48FPD using GLC-SX-MM's.  The 9500 is running 16.9.3 and the 2960 is running 15.2(6)E1.  To use the GLC I have the QSFP to SFP converters install (CVR-QSFP-SFP10G) and I know these work because I have a GLC-T in the switch that is working fine.  

When I try to connect with the GLC-SX the 9500 says that it's linked and trunked, but the 2960 never shows a link.  I've checked the logs and the logs for the 9500 shows Fo1/0/1 up and line protocol up,  though CDP never shows the 2960.  From the 2960 side, there's nothing in the log that shows it even made and attempt.

Am I missing something?  I know both will do 10G, but I have 1G optics that I was hoping to use until I could get them swapped out.

Thanks for any help you can give.

[Reza Sharifi]

Hi,

I think on the 2960x model you are using, the uplinks are SFP+ only, which means they support 10G only.

HTH

[rlcole]

We use the 1G SFP's in most of our 2960X's with no problem. Where the 9500 is destined to go currently has 2960Xs connected 1G back to a 3750G. The 2960 is also correctly identifying the SFP, as is the 9500. So both sides know what it is, I just have to figure out why it's not linking fully.
It's probably also worth noting that these are true Cisco branded SFP's, not third party units.

[Leo Laohoo]

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@rlcole wrote:

I have a C9500-12Q-E

The 9500 is running 16.9.3

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I know the reason why:  CVR-QSFP-SFP10G and C9500-12Q are not compatible.  

Under "Hardware Features Introduced on Cisco Catalyst 9500 Series Switches-High Performance" it is stated that the compatible models for the CVR-QSFP-SFP10G are the following:  C9500-48Y4C and C9500-24Y4C

WARNING:  16.10.1 is very, very buggy.  Use this version at your own peril.  (I am not even recommending this.)

CVR-QSFP-SFP10G is compatible with the C9500-12Q if the switch is running 16.10.1.

You might try loading the switch with 16.11.1 and see if it works.

[rlcole]

Do you know if this is a change from 16.8.x?  The release notes for 16.8 specifically states that it's compatible with the 9500-12Q:  Release Notes for Cisco Catalyst 9500 Series Switches, Cisco IOS XE Fuji 16.8.x

I had to move off of 16.8 due to a bug that kept filling up the log with SNMP errors, I'd assumed that since 16.9 is the recommended version that it had all the same HW compatibilities that 16.8 did, I know, probably not a safe assumption.  

[nazimkha]

I see a contradicting version on the SFP compatibility tool (TMG), it shows the the adapter CVR-QSFP-SFP10G and the SFP GLC-SX-MMD are supported since IOS XE 16.8.1

https://tmgmatrix.cisco.com/?npid=188

[rlcole]

Thanks for confirming what I was seeing and thinking in the release notes.

This has got me baffled... because on further testing, the 9500 talks fine to a 3560-8 with a SX SFP in it, but... so does the 2960X.   It's really a communications issue between the 9500 and the 2960, when using a GLC-SX.   GLC-T works, SFP+ works... Things that make you go hmmmm

[rlcole · Accepted solution]

Solved!

The solution is to add "speed nonegotiate" to the interface configuration on the 2960X's end.  A quick cast to TAC found the solution.  I should have caught that and tried it, live and learn.