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New Member

GBIC WS-G5486 Connectivity issue

Dear All,

We have a problem with the GBIC WS-G5486 regarding its connectivity with the

fiber cables as explained below:

The problem simply is that the link distance is less than 1 Km, and the

Fiber Optic cable is single-mode, i'm installing the GBIC both ends in

7206-VXR with NPE-G1 router, the status of the interface in one side is

up/up and the other end is down/down...!!! when i disconnect the cable from

the down/down side, the other end becomes down/down, which means that there

is some kind of signaling reaches that end.

Any Idea can help us to resolve this problem??

Thanks in advance...

Best regards,,

Magdy Hossein

New Member

Re: GBIC WS-G5486 Connectivity issue


We have similar problem between 2 switches.

A 2950 switch with a WS-G5486 module and on the other side a 2970 switch with a mini gbic module WS-G5486.

At a given moment de fiber link goes down.If I ping from the 2950 switch to the 2970 switch there is no reply,2970 is not accessible. If I to a "show intf gi0/2 "(link to the 2970) the interface is up. After a while the link is back up. If I check the logs on the 2970 the interface to the 2950 was down.but for the 2950 the interface was up.

What can cause this problem ?

the 2950 WS-G5486 module has a serialnr.AGS09110372

The 2970 WS-G5486 module has a serialnr.FNS0921D13N

So AGS and FNS is this a different manufacturer and can that create problems.

Best regards

Michel van Riet

VIP Purple

Re: GBIC WS-G5486 Connectivity issue


in addition to Michel´s post, you might want to try and shut/no shut the interfaces. I had a very similar issue a while ago. Eventually I got it working by removing the GBICs, entering the interface configuration, configuring the interface for ´speed nonegotiate´ and plugging the GBIC back in.

Also, there is a hidden IOS command that might solve the problem when 3rd party GBICs are used, not sure if this is supported on the 7206:

7206#conf t

Enter configuration commands, one per line. End with CNTL/Z.

7206(config)#service unsupported-transceiver

Warning: When Cisco determines that a fault or defect can be traced to

the use of third-party transceivers installed by a customer or reseller,

then, at Cisco's discretion, Cisco may withhold support under warranty or

a Cisco support program. In the course of providing support for a Cisco

networking product Cisco may require that the end user install Cisco

transceivers if Cisco determines that removing third-party parts will

assist Cisco in diagnosing the cause of a support issue.



New Member

Re: GBIC WS-G5486 Connectivity issue


Thanks for the info.

We did a shut and no shut but the problem returns

Perhaps we have to try the "speed nonegotiate"

We are using Cisco Gbic's (cisco reseller).

But I think that we have a mixed of manufacturer on the GBIC's (see serialnr in previous mail)


Re: GBIC WS-G5486 Connectivity issue

Hello Magdy,

You seem to have an unidirectional link condition. I know of two reasons for that:

1) one of the fibers of the pair is broken

2) one GBIC transmitter and/or receiver is broken

Regarding option 1):

Can you swap the fibers and see whether the interface down/down swaps sides? Replace the fiber in this case.

Regarding option 2):

In case the test above reveals no change in up/up and down/down, then you might have a GBIC problem. Either the receiver on the down/down side or the transmitter on the up/up side is broken. So replace a GBIC at a time until you get the link working.

Hope this helps! Please rate all posts.

Regards, Martin