Trying to connect three 2950-48T SI switches G0/1 ports to a 3550-12T switch. No connectivity between the 2950 and 3550 switch is made. I have checked the switch ports out by connecting the 2950 G0/1&2 and all the 3550 G ports all check out good.
The 2950 switch IOS is c2950-i6q4l2-mz.121-22.EA4.bin the 3550 switch IOS isc3550-ipservices-mz.122-25.SEB4.bin
When restarting the 3550 switch the connections to 2950 G0/1 ports light up and appear to be active but as soon as the 3550 switch has booted up fully the lights go out and show in the down-down state.
Can you show us the config on the 3550? Do you have any of the ports on the 3550 set to no switchport? Try going onto the interface, type switchport, and see if you get a connection.
Please check your cabling. It is best to use a straight cable for this as the GB-interfaces will negotiate the required crossover. If you are using a cross-cable please try replacing it, not all crosscables have the correct wiring for gigabit.
You may also try to set both sides fixed to trunk, nonegotiate and fix the encapsulation on the 3550 to dot1Q.
The problem was a cable issue I replaced the cat5e cables with cat6 cables clearing the connectivity problem.
Thank you for your input