SFP module not working

Hi,

Module install and recognized on 3650 switch. Administrvely brought up. But the line is down. Not very familular with SFP installation. do I have to consider anything else on configuration?

If you need more info shout

Thanks in advance!

Find more posts tagged with

SAVE $250 on Your CISCO Boot Camp — Use Code "EXAM26"

Exclusively for TechExams members for Infosec Boot Camps starting before April 30, 2026

View CISCO Boot Camps

Comments

networker050184

I'd ensure the SFP is compatible with the IOS image you have first. Second what is it plugged into, a crossover patch between two switches? Have you tried another patch cable?

Pash

networker050184 wrote:

I'd ensure the SFP is compatible with the IOS image you have first. Second what is it plugged into, a crossover patch between two switches? Have you tried another patch cable?

Yeh im sure it is because it recognizes the module and the ports are recognized. They connect via fibre link switch to switch. We replaced cabling, just wanna know if we miss anything.

larkspur

silly question but is the other side connected?

3650 <-> ????

trunking this port?

networker050184

What IOS are you using?

dtlokee

You need to make sure they arethe same type at both ends (SX,LX,ZX) and that you have connected them with the TX and RX sides reversed on one end (a crossover). Other than that there shouldn't be too much to it, unless it's defective (the GBIC market has been a huge one for countefeit products)

Pash

dtlokee wrote:

You need to make sure they arethe same type at both ends (SX,LX,ZX) and that you have connected them with the TX and RX sides reversed on one end (a crossover). Other than that there shouldn't be too much to it, unless it's defective (the GBIC market has been a huge one for countefeit products)

Cheers DT. This is a legit module, all purchased from cisco vendors.

networker050184

The reason I asked about IOS is I read you need 12.2(20)EX to support this.

JohnDouglas

what does "test sfp show inf" give?

could be a problem with rommon code but in all likelihood it's just a mismatch of sfps like mentioned above.

but - remember with SX-SX you'll need multimode fibre! the rest are singlemode.

i wasn't so popular when an engineer drove 3 hours to site and forgot to tell him he'd need multimode (rarely used for anything these days i think!)

have fun. incidentally with the new SIP cards cisco has brought out they have a whole new load of SFPs. they can cope with the higher operating temperature in the densly packed sip.

Pash

Dt was spot on correct. This was actually my colleagues problem at another site but he needed a hand so i looked at the conf remotely for him and could see it was all good. Just needed to make the cables reversed on one end.