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Fibre between Cisco ME6524 and Extreme Summit switch

Hi folks

I am having trouble with a fibre connection between a Cisco ME6524 and a Extreme Summit switch.

I am using LX Single mode SFP's at both ends, but the link won't come up.

If i set "speed nonegotiate" at the Cisco side, I get at link led at the Extreme side. The technician responsible for the Extreme switch tried to set auto off 1000 full on the port, but nothing happens at the Cisco switch..

The fibre has been inspected, and found OK with nearly no loss (about 10 metres of patch). Also tried with 5db attenuators, but no luck..

Anyone got a solution, or at least a tip?

Hall of Fame Super Silver

Re: Fibre between Cisco ME6524 and Extreme Summit switch

Hello Lars,

I had similar problems connecting an Agilent router tester gigabit port to a giga port on a c6500.

Fist of all, I would keep

the command speed nonegotiate on the port that in my case solved the issue.

you can also try to use 10 dB attenuators.

You can also add the following

switchport nonegotiate

that could have some positive effects

hope to help



Re: Fibre between Cisco ME6524 and Extreme Summit switch

How long did you try to connect BEFORE you tried the attenuators?

You could have burned out the receivers. LX lasers at 30 Meters is nothing for attenuation.

I'm not sure but 5db night even be inadequate.

Try some other known-good SFP/GBICs and make sure you're hitting the proper signal level window adding attenuation as needed to get the signal level down before you connect them.

Make sure your fiber ends (and receptacles) are clean. It doesn't take much to block a light beam that's only 8 micron diameter.

Good Luck


Hall of Fame Super Silver

Re: Fibre between Cisco ME6524 and Extreme Summit switch

Hello Scott,

5 db is too less attenuation to get a working link with this type of GBIC.

However, I don't think you can damage the receivers so fast in a few minutes.

otherwise builders should put a red warning label on them.

I've noticed in our production network that SFPs are more likely to become not working in uplinks of c4506 access switches then traditional GBICs but in some mounths time window not hours.

best regards