1G SFP (GLC-TE) seems not to work with C9300LM-24U

[gabrielgrabner]

Hello!

I might have encountered an issue with the Cisco C9300LM-24U switch. When using an GLC-TE SFP on one of the 25G SFP ports, I get a link but no layer 2 connections seems to work. when configuring switch 1 (9300LM) with ip 10.1.1.1/24 and switch 2 (9300LM) with ip 10.1.1.2/24, i get an ARP incomplete and no answers to my pings inbetween when connecting the 2 switches with 2 GLC-TE and a cat6 cable. When plugging the same cable to the normal copper ports on the switches, ping and arp works fine.

I already made a few tests with C9300-24 (normal model, not the LM one) or IE2000-8, the same SFPs work without problems here. Only when one C9300LM comes in, the problem appears.

The GLC-TE should be compatible to the C9300LM according to the compatibility matrix. The C9300LM is running on the latest version 17.09.03. The GLC-TE is recognised by the C9300LM and the Port is showing "10/100/1000BaseTX SFP" with 1G/full speed.

Any ideas why this does happen? Or how can i get the GLC-TE working with the C9300LM ?
Thanks in advance!

[Leo Laohoo]

(Oh no.  Not another one.)

What is the optic's country of origin, Malaysia or China?

[gabrielgrabner]

You mean the GLC-TE module? It says made in China.

[Leo Laohoo]

What is the first seven characters of the serial number of the GLC-TE? 

Just for giggles, upgrade the switch to 17.12.1.  

[gabrielgrabner]

Serial starts with AVC2438****
Is the upgrade necessary since 17.09.03 is the current recommended version?

[Leo Laohoo]

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@gabrielgrabner wrote:
Is the upgrade necessary since 17.09.03 is the current recommended version?

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I am suspecting this is an firmware bug but I cannot be certain until the switch is upgraded/downgrade to a different train.  

Please share both output to the command "sh interface <GLC-TE ports from both switches>" with it is in a broken state.

[gabrielgrabner]

attached the two outputs.

I upgraded the firmware to 17.12.1, now the link doesn't even come UP. Any advise?

[gabrielgrabner]

I've tried a few things now:

Version 17.09.03 - link comes up, but no arp entries
Version 17.09.04 - no link comes up but sfp is recognized
Version 17.12.01 - no link comes up but sfp is recognized

Any ideas?

[Leo Laohoo]

If one side is GLC-T and the other side is the copper port, does the issue still remain?

[gabrielgrabner]

Yes, issue still remains, connection does not work!

When I have the GLC-T in the IE2000 and connect the cable to a normal copper port on the C9300LM, the connection works!
Vice versa, the connection also does not work!

[Leo Laohoo]

Raising a TAC case is a waste of time.  If this is a bug, there time it will take for Cisco to release a fix will take several years.  

My recommendation is to look for 3rd party optics.  FS[.]com is very popular for a reason.

[gabrielgrabner · Accepted solution]

Cisco TAC confirmed this is a new bug:
Bug CSCwh51416

Cisco Developers are already aware, and they are checking for a solution.

[gabrielgrabner · Accepted solution]

Bug was fixed by Cisco with 17.09.05 which is also recommended by now!