Catalyst 2940's, No Link Light?

[daytonajames]

Trying to hook up a 2940 to a 3560. Right now we have a remote location that is connected via a hub to a 3560, with the fiber strands connected through a transceiver. We just got a 2940 for this location so that we can run the fiber straight to the gigabit port. However, I can't seem to get any link light on the 2940 with the fiber connected. Since the 2940 only supports dot1q, and since you cant set encapsulation on the 2940, I figure just setting the g0/1 port on the 2940 to switchport mode dynamic auto, and the connecting gigabit port on the 3560 to encapsulation dot1q and switchport mode dynamic desirable would work? Still no link light. I have tried pretty much every combination of trunking, using switchport mode trunk to try and force the switch to trunk, but nothing seems to work. I know its not a layer 1 issue because the same fiber connection works fine with connected through a transceiver to one of the fast ethernet ports on the 3560. Anybody know of a possible issue here?

BTW, I was thinking that the problem might be with VTP? I have the 2940 set to transparent mode, as it only supports up to (I think) 100 vlans. I haven't tried setting it to client, but I dont see how this would cause the 2940 to not have a link light with the fiber connected.

Thanks for any help in advance.

 

[daytonajames]

Also, I know the gbic is fine because I had it connected to our core 4510 switch when I was setting the 2940 up, and it trunked fine then.

 

[jdeisenm]

What are the config on each switch port?

I think it should look something like this.

3560
interface GigabitEthernet0/1
switchport trunk encapsulation dot1q
switchport mode trunk
no ip address

2940
int g0/1
switchport mode trunk

 

[vipergg]

How is it hooked into the 3560 , is it a straight fiber connection or are you using a media converter ? Also what model 2940 are you using 2940-8tf ??? If so then the sfp is gig only and you have to be hooked into a gig fiber port on the 3560 not a 100 meg port .

 

[vipergg]

After looking further I see that it has a 100 meg fiber port on it along with a gig fiber , it says you can only have one active at a time so I would check to make sure the gig fiber is in shutdown state.

 

[daytonajames]

Right now the hub is connected to the 3560 via a transceiver. What we want to do is run the fiber strait from the 3560 to the 2940, no converter. And yes, the port on the 3560 and the 2940 that the fiber is connected to is gigabit, not 100meg. I haven't noticed if the 100meg fiber port is administratively down or not, I will try that and let you know. Thanks for the ideas.

 

[daytonajames]

OK This is really wierd. I connected an SC patch cable to the gigabit port on the 3560, and then to the gigabit port on the 2940. The link light went up, the port went up, and everything seemed fine. As soon as I unplug the SC cable and plug the ST/SC cable that we have running, the link light goes off and the port goes down. I know the cable itself is fine, because its running through a transceiver into the 3560, and it works fine. I don't really know what's going on.