2948 - gbic ports

[mattyjenks]

Hi all,
I have a 2948 with two GBIC's to link to others

recently ive had problems with some 2948's whereby the gbic link disconnects and wont come back up.

i have temporarliy replaced these with 3500's

on test i connect the gbic and the port comes up then about 15 seconds later is will go down.

there is no config on the ports so they should just trunk shouldnt they???
ive even removed all config from the test switchs and they still connect then disconnect.

Any help would be appreciated.
matt

 

[vipergg]

They aren't going to trunk without configuring them properly . They should connect if the ports are admin up the fiber connection is ok and you have the same gbics on each end . ie lx to lx , sx to sx .

 

[buraglio]

Are you using fiber GBICS? I had some serious failure rates (like 5 out of 20) with copper gbics, just something to consider. As vipergg said, they won't "automatically trunk". If the light levels are correct and the optics are the same they should see link though after setting them to admin up.

nb

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Nicholas D. Buraglio

http://www.buraglio.com/nick/gpg-pub-key.txt

 

[mattyjenks]

thxs both
yeah its a fiber gbic - sx

both are set to admin up but no link will stay up.
the gbic's and fiber leads have both been swopped for brand new ones so it seems to be the switch and not the componenets.

 

[buraglio]

Test the light levels on both ends.

----------------------------------------
Nicholas D. Buraglio

http://www.buraglio.com/nick/gpg-pub-key.txt

 

[vipergg]

As buraglio said test the strands and see if you have adequate light coming out . Also if someone had configured udld on the ports and you have a one way link then the switch will automatically shut the port down , usually it will go into a errdisable state . To me it doesn't sound like a switch problem , we have never seen a problem with the 2948's. You said you are using sx gbics , are you sure you are using multimode fiber ?

 

[vipergg]

Does it indicate anything in the logs on the 2948's when the link goes down or on the switch it is connecting to ????You should be in the console on both ends on the link and see if it tells you anything when it goes down .