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New Member

3750 switch port trouble, connecting to a 3800 router

Have a 3750 Switch connected to a 3800 series router using fiber. The 3800 series switch is externally managed.

On the switch interface I dont get an LED, plus when I run a "show interface gi 1/0/20" I get the following:

GigabitEthernet1/0/20 is down, line protocol is down (notconnect)

The port is configured similar to as follows:

no switchport

ip address 192.168.1.1 255.255.255.0

ip route-cache flow

with the router port its connected to being 192.168.1.2/24.

Have switched cables but no difference, cant get the port up and running.

How can I resolve this

10 REPLIES

Re: 3750 switch port trouble, connecting to a 3800 router

Hi,

Please make sure that the Rx is connected to the Tx (and vice versa), and that the other end is not adminshut.

HTH, please do rate all helpful replies,

Mohammed Mahmoud.

New Member

Re: 3750 switch port trouble, connecting to a 3800 router

I have tried that too, but it hasnt made a difference

Re: 3750 switch port trouble, connecting to a 3800 router

Hi,

Ok, this is a physical layer problem, please make sure that the other end is not adminshut (contact however is managing it), and then check the physical path between the 2 devices.

HTH,

Mohammed Mahmoud.

New Member

Re: 3750 switch port trouble, connecting to a 3800 router

I thought so too, but when I had confirmed that the remote port isnt in shutdown.

Also physically checked the cable run, to be sure we were dealing with the right connection.

Re: 3750 switch port trouble, connecting to a 3800 router

Hi,

Ok, lets go to the last choice, can you please try another interface.

HTH,

Mohammed Mahmoud.

New Member

Re: 3750 switch port trouble, connecting to a 3800 router

Didnt have a free port, but had another ideal L3 switch, so I replicated the necessary configuration, and tried it on one of the gigabitethernet ports, and it still wont come up.

Have considered having the fiber checked again, but a colleague said that the particular finer worked on another connectiong that since became idle

Re: 3750 switch port trouble, connecting to a 3800 router

Hi,

Ok, finally its either a problem on the remote router (you should have the other end administrator do the checks for you), or its a path error.

HTH,

Mohammed Mahmoud.

New Member

Re: 3750 switch port trouble, connecting to a 3800 router

Hi,

as suspected it was a problem with the remote router. The interfacing gigabitethernet port had its duplex and speed manually set, which caused the problem. When switched back to auto, the link came up. Unfortunately it took a whole day just because am seated in Europe, while the remote admin is on the US Pacific Coast, making it hard to find a time when we are both awake and in office to resolve problems at the same time.

Thanks all

Re: 3750 switch port trouble, connecting to a 3800 router

Hi,

You are very welcomed, and i am glade it worked out :)

HTH,

Mohammed Mahmoud.

Purple

Re: 3750 switch port trouble, connecting to a 3800 router

Sometimes on the routers the ports are bundled together with a fiber and a copper together and you have to select in the config which interface you want to use I would have whover is responsible for the 3800 check for something like that . Unless you can get a look at the 3800 this could be tough .

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