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Community Member

Subinterfaces on Router

I created 3 subinterfaces on a 3800 router for VLANs on different switches but the subintefaces protocl shows "down" {see attached for output}. Can someone tell me what I missing?

Thanks in advance,

sK

5 REPLIES
Hall of Fame Super Blue

Re: Subinterfaces on Router

Hi

What is the gigabit interface connected into at the other end. It should be a switch and the port on the switch needs to be configured as an 802.1q trunk.

Jon

Hall of Fame Super Bronze

Re: Subinterfaces on Router

The physical interface is down, verify cabling.

What device is this physical interface attached to?

Can you post the configuration for the physical interface on this router and the device it's attached to?

__

Edison.

Community Member

Re: Subinterfaces on Router

The router's phyiscal interface is connected to a trunk port on a 3560 switch. The port has been verified to be configured properly. Attched is the output of the port status on that switch.

Hall of Fame Super Blue

Re: Subinterfaces on Router

Okay, can you

1) check speed/duplex settings on both the 3800 and the 3560 switch

2) Try a different cable.

3) Post full interface configuration from router

Jon

Community Member

Re: Subinterfaces on Router

I replaced the path cord and everything worked fine. I should have checked the patch cord first but I didn't since the same patch cord and setting was working fine with a different switch.

Thanks so much for your efforts.

sK

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