Cat 3550 over 5484 GBIC

[pkpatel]

Hello,

I tried to connect two 3550s, one with inline power using 5484 GBIC module on each side and fiber link which was in use and in working condition. Initially, none of the port became active. Eventually, port on one side of the switch became active. There is no other fiber run in the facility.

Fiber is going to be tested, but I like to see what else can be done to solve the problem.

Both sides are configured to be dot1q trunks.

Any thoughts? Please reply.

Paresh.

[frenzeus]

Hi Paresh,

I have had certain issues like this before. But after a thorough check on configuration of the 3550s, everything should work. last thing i did was to clean the fiber connectors and when i inserted it to the GBICs, did a no shut and the interfaces were up.

U could also use a fiber tester to test the fiber media end-end that it is working 100%.

[pkpatel]

Hello,

Thanks for your response. I verified the config and found it ok. Cleaned the connectors and did sh and no sh on both sides.

What blows mt mind is, why would a port on one side come up (turns Green) and the other side does not.

I am thinking that it might have to do with signal strength. The fiber test will tell us if that's the case.

Thanks again,

Paresh.

[frenzeus]

Hi paresh,

u could actually check and see if either side of it is actually receiving signal. Unplug the cables and hold the tip of the connectors close to ur palm etc and see if u're getting any red-light! At least that gives u a good indication if both sides are actually receiving the transmitted light from the GBICs.

It could be the case of UDLD, where the local side receives the signal, but not the remote side.

[pkpatel]

Hi,

The fiber test revelaed that a couple of strands, 1 nd 3, were questionable. Right now, we are using fiber strands 2 and 4, fiber to cat 5 transceiver, which is working correctly.

However, when I connect 3550s using GBICs over strands 2 and 4, port on only one side comes up. The second side remains un-lit.

The config is:

========================================

int g 0/1

switchport trunk encapsualtion dot1q

switchport modr trunk

!

========================================

Has anyone seen this kind behavior before?

Any suggestion? Please post.

Thanks.