Cisco switches don't talk to each other 3

[msworld]

We tried to connect two buildings using fiber cable. One building has Catalyst 3520 and other building has 3750. But they don't talk to each other and the led has no light.

To find out the problem, we bring these two switches in the same room and connect them directly with a 5 feet fiber cable. They still have the same problem. The following are what i try so far.

1. Connecting between two 3500 switches directly.
2. Connecting between 3750 and 3500 switches directly.
3. I also tried different fiber cable.
4. The sh int shows ?GigabitEthernet0/1 is down, line protocol is down?. What could be the problem?

Bob Lin, MS-MVP, MCSE & CNE
How to Setup Windows, Network, VPN & Remote Access on

http://www.HowToNetworking.com

 

[MTandSAV]

that looks to me like a layer 1 problem, ie cable or ports. you should be using cross cable. If you use a straight cable you probably need to turn on mdix

CCNA, CCNP..partly

 

[rmcp2k]

Bob,


do a sh run

verify that gi0/1 is trunk if it then it must be administrative shut down

do int gi0/1 then issue a no shut on that

 

[lerdalt]

double check your gbics. And like MTandSAV said, you need to check your cable...try flipping one end of the fiber cable around

can you make the 2 switches talk with a cat5 crossover cable?

 

[msworld]

Thank you for the help.

1. I did try flipping one end of the fiber cable around.
2. That is correct "verify that gi0/1 is trunk if it then it must be administrative shut down". However, no shutdown doesn't make any differences.
3. Cat 5 crossover cable connecting two switches works.

Bob Lin, MS-MVP, MCSE & CNE
How to Setup Windows, Network, VPN & Remote Access on

http://www.HowToNetworking.com

 

[ptdog]

You could possibly have bad gbic or sfp. One thing to do is power up each switch and make sure the sfp and gbic is plugged in. Without plugging in fiber patch cable, look inside each sfp or gbic, one of the ports should have a red light. If one does not, then the gbic or sfp could be bad.

This happened to me, two switches connected via fiber wouldn't trunk. It turns out it was bad gbic when I checked the light.

 

[GunnarD]

Check that your GBIC is the sametype and using the same frequency.

 

[msworld]

Thank you for all help. We had a consultant come to take look them. He could not fix it. He think it is hardware issue. He brought the two switches back to his office to test them. Will post back with the result.


Bob Lin, MS-MVP, MCSE & CNE
How to Setup Windows, Network, VPN & Remote Access on

http://www.HowToNetworking.com

 

[JRMS]

What was the fix????

 

[msworld]

Update:

1. They found one of 3500 switches was broken and another one is good.
2. They brought the good one back. At beginning , the 3500 and 3750 don't talk to each other (no green light).
3. Finally, they found one of gbic in the 3750 switch was broken (the 3750 has 4 gibcs and two have been using for years). The problem is if they have the bad gbic in the switch 3750 doesn't talk to the 3500. After they took it out, both switches works.

Thank you for all inputs.

Bob Lin, MS-MVP, MCSE & CNE
How to Setup Windows, Network, VPN & Remote Access on

http://www.HowToNetworking.com