[c-nsp] IP communication problem

[Peter Rathlev]

On Sat, 2010-08-14 at 18:19 -0500, Christopher J. Wargaski wrote:
> 17w2d: IP: s=172.16.0.6 (local), d=172.16.0.5 (FastEthernet0/0.501),
> len 100, encapsulation failed

Encapsulation failed in this context simply means there's no ARP entry
for the destination. The router cannot create the relevant L2 frame
without it.

Your topology isn't all clear, but as Heath points out it might be the
switchport configuration facing the 2801, or maybe somewhere else.

> From the 2955 switch in the middle, I can ping a Vlan503 interface on
> the 3560G. Also, I see the both the 2560G and the 2801 in the CDP
> neighbor output.

You can see both? Out of the same port? That's a little strange from
your description of how they're connected. As if the "FS14" 3560 is
relaying CDP messages from the 2801.

Maybe post the interface configurations all the way through.

-- 
Peter