Cisco 3550 to 3550/2950 trunk

[paveldudaibm]

Hello,

I'm trying to connect Cisco 2950 to 3550 and configure trunking but my Fa interfaces do not get up at all. I have tried cross-over cable and straight cable as well however I do not see any link on those ports. I have even tried to connect other 3550 and again no luck as if either cable or port is broken (ruled out that possibility by using other cables and different ports). When I use connection with the exactly same configuration on the Gi port between two 3550 using fibre then it works fine so i wonder what could be wrong and why metalic cable doesn't work.

Any idea what might be wrong?

Just for reference here is the config on the port(s):

interface FastEthernet0/2
 description Trunk connection
 switchport trunk encapsulation dot1q
 switchport mode trunk
 ip dhcp snooping limit rate 90
 ip dhcp snooping trust

[chrihussey]

Is your crossover cable the following pins:

1---3

2---6

3---1

6---2

Have you tried removing all configs and just connecting them that way?

What is the status of the ports...up/down or down/down?

Not ruling out bad ports on one or the other if you are doing things right, just asking is all.

Regards

[paveldudaibm]

To be sure I've created my own crosslink cable so yes 1-3 and 2-6 swapped.

Both ports are down (notconnect).

[chrihussey]

Doesn't sound like you are doing anything unusual. May just be a bad switch.

[paveldudaibm · Accepted solution]

I have tested another 3550 and 2950 switch and basically ended up at the same state. Interesting was that when I connected both switches for the first time I got link on both ends but then the 2950 switch did sort of "reset"?! (all diods got light up for a few seconds on all ports) and after that it exhibits same behavior eg. no matter what I do or reset the link between device is not established (diods not even blink). Unfortunately I did not have the console connected at the first time so I can't even say what has happened. Anyway the fibre links are working fine so I did throw out the C2950 and kept just 3550 connected via fibre...