encapsulation failed udp

[tmcmillion]

I have numerous network issues that started between 2 of my campus sites across a T1 between 2501's. They can't save file to the network, can't get to outlook, illegal operation and numerous others.

When I look at "debug ip packet detail" on the local router I am getting the following message "IP: s=172.19.200.17 (Ethernet0), d=172.17.3.6 (Ethernet0), len 229, encapsulation failed UDP src=138, dst=138". I have never come accross this message and am not sure if it is related to the network problems or not. Any thoughts on this?

[burtsr]

The encapsulation failed error message indicates that when the router attempted to build the layer two header there was some necessary piece of information that the router did not have, so it could not build the header and not send the packet.

The first thing I would check is the MAC address of the destination. Do a show arp and look to see if the table includes an address for 172.17.3.6.

It also strikes me that the source and destination are both on Ethernet 0. Is this some situation where you have secondary addresses or something like that?

[Georg Pauwen]

Hello,

UDP port 138 is used for NETBIOS Datagram Service, I assume you do not have any access lists blocking that port ? Can you post the configs of both 2501s ? Which IOS version are you using ?

Regards,

Georg