Nexus 5672UP/ GLC-T Module Issue (Link not connected)

[nsti_0682]

I've run across an issue with a new 5672UP switch and GLC-T modules that I was hoping someone had an answer for. When I insert the GLC-T modules into the 5672UP and plug in another device (via CAT 6 Ethernet), the other device (an ASA in this example) gives me a link light and show 'UP/UP' but the interface on the 5672UP shows "Link not connected". I've tried another port within the first 32 ports with the same result. When I insert the GLC-T module into one of the UP's (ports 33-48), it works just fine. I can't think of any other reason for this behavior other than a bug. I'm running the latest version, 7.3(1)N1(1). I'd open a Cisco TAC case but I'm waiting on the devices to get covered under a contract which will likely take a week or so. In the meantime I figured I'd try this forum.

[Wes Austin]

Looks like you need GLC-TE for 5600. GLC-T is not supported:

http://www.cisco.com/c/en/us/td/docs/interfaces_modules/transceiver_modules/compatibility/matrix/GE_Tx_Matrix.html#_Toc462044450

Wes

[nsti_0682]

I saw that but I am confused because 5600 datasheet does list the GLC-T as supported.

http://www.cisco.com/c/en/us/products/collateral/switches/nexus-5000-series-switches/datasheet-c78-730760.html

[Wes Austin]

Double checking, GLC-T should work for 5600.

Try to hard code the speed on the interface to 1000 MB

speed 1000

If this does not work:

See if this command on the interface has any impact on the link status:

'service unsupported-transceiver'

Wes

[nsti_0682]

Yea I already tried both. You have to manually set the speed to otherwise you'll get 'SFP validation failed'. 

[Wes Austin]

Try to disable auto-nego:

no negotiate auto

Also, are we sure this is a supported Cisco GLC-T?

-Wes

[nsti_0682]

Yea I tried disabling negotiate auto and the link status went to 'SFP validation failed'. They say GLC-T on the outside and below is the output of the 'show interface e1/1 transceiver' command...

Ethernet1/1
transceiver is present
type is SFP-1000BASE-T
name is CISCO-METHODE
part number is GLC-T
revision is E
serial number is XXXXXXX
nominal bitrate is 1300 MBit/sec
Link length supported for copper is 100 m
cisco id is --
cisco extended id number is 4

[Wes Austin]

If you have multiple GLC-T exhibiting the same behavior, I suspect it is something to do with that specific transceiver batch.

I would open a TAC case and have them send you a replacement to rule out hardware.

-Wes

[nsti_0682]

Yes all of the GLC-T's exhibit the same behavior but because they all work in ports 33-48 but not 1-32 I don't see it being a GLC-T issue but rather an issue with the switches themselves. 

[Wes Austin]

Researching some internal knowledge bases, we have customers using those GLC-T with those switches and no issues.

I believe this could be a GLC-T specific issue, but until you have a replacement or a TAC case to investigate the switch, it will be hard to tell.

-Wes

[nsti_0682]

What code version are they running?

[Wes Austin]

Earlier releases than 7.3....some are on 7.0.

7.0(1)N1(1)

Are we sure the ASA interface does 1GB ? It's not a 10/100 port is it?

What if you put 2x GLC-T in the Nexus and loop back to each other?

-Wes

[nsti_0682]

Ok. I'll try that code version.

Yes I tried plugging in a 2960 and also my laptop to rule out something with the ASA.

I also tried looping them as well. Same result.

[Wes Austin · Accepted solution]

I just found this, looks pretty specific to your issue.

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvb42221/?reffering_site=dumpcr

Please try one of the fixed releases and see if there is any positive results.

-Wes

[nsti_0682]

Good find. I suspect this is the issue although none of the "Known Fixed Releases:" (7.1.5 or 7.3.2) are available for download...the latest available for download are 7.1.4 and 7.3.1.