I have 2 routers connected by an HP switch. The 2 routers have incomplete ARP entries for each other. The switch sees the correct MAC address on their respective ports. I've changed cables on both sides, moved switch ports for both devices, and have not been able to resolve this. One router will have an ARP entry for the other every so often, but still no comms between the two. I've assigned static ARP entries just for kicks, and got the same results. Here are more specifics about each router:
Router 1: 2801 (12.4(22)T) port F0/1
Router 2: 3825 w/ HWIC-4ESW port F0/0/3 (in assigned access vlan)
I've also noticed that the vlans on the HWIC module apparently are completely independent of the vlans defined on the router itself. For example, I have G0/1 of my 3825 trunked with 2 subinterfaces (vlan 8 & 40). I have vlan 500 assigned to one of my HWIC ports. The router vlan database only shows the HWIC vlan definitions.
Is there anything else I can try to narrow the problem down? I tried removing all assigned vlans on the HWIC card, but still no luck.