06-21-2007 11:49 AM - edited 03-05-2019 04:53 PM
Hello
We have the following scenario: A router cisco 7206VXR (NPE300) connected with a cisco WS-C2950SX-24.
The router is showing a mismatch configuration between its interface fastethernet 0/0 (on I/O card C7200-IO-FE-MII/RJ45) and the switch interface FastEthernet0/1.
The interface on the switch is configuring speed/duplex auto
And the router interfaces as following
interface FastEthernet0/0
description To LAN
ip address 10.200.10.1 255.255.255.0
ip nat inside
duplex full
no clns route-cache
We tryed to fix the issue, changing the router config to auto, but this card only support full/half duplex configuration.
Then the option was change the switch to full duplex hardcoding but when we did it the interface went down and only when we changed to auto the interface came up.
Any idea?
Thanks in advance
06-21-2007 01:12 PM
Normally on a router -> switch connection the best practice is to set them both to 100/Full. If you do this and the interface goes down, I would check/change the cabling.
Also, you could try a different switch port -it's not unheard of for one to go bad.
HTH,
Paul
06-21-2007 01:29 PM
That is exactly the behavior I would expect with that configuration. Any time you have one side of a link trying to negotiate when the other side is not, the negotiating side (in this case, the switch) is going to fall back to half-duplex. You have the router set to full duplex - thus, you have a duplex mismatch.
I find it hard to believe that the router card does not support auto-negotiation. However, if it doesn't then the solution to the problem is to set the switch port to 100/full.
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