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New Member

Virtual Interface Routing Issue

I have a 3845 router with 2 4 port ESW modules. I've configured virtual vlan interfaces and put the physical switch port int's in their respective VLAN. However, I cannot get layer 3 traffic to forward out any of the switch ports.

I have a 2800 configured the same way and it works fine. Is there something different in the 3800 architecture for this to work differently?

I run a debug IP packet, I get encapsulation failed or unroutable. On the other hand, the arp table populates the IP I'm trying to reach with the correct MAC. The routing table on the router shows my interface as connected as well. Plus,I just upgraded the router to the latest Enterprise IOS.

The built in Fast Ethernet interfaces route layer 3 traffic just fine; so it's something with the interaction of IOS and the 4 port switch modules for routing layer 3 traffic. I'm at a loss!


Re: Virtual Interface Routing Issue

Maybe you can post a "show ip int brief" and the router config and maybe we can see something. Did you you create the layer 2 vlan ? Does it sh up with a show vlan-switch command?

New Member

Re: Virtual Interface Routing Issue

Good Afternoon Glen,

Sure, I'll paste some of the config; it's rather long and a sh ip int br below. Yes, I can see the vlan's if I perform a show vlan-switch. I've been banging my head up against the wall for days on this. I'm in crunch time, so maybe you can see something. Just to let you know; the network I'm having issues with is configured on the vlan1 interface. I have the physical int (Fa0/2/2)in vlan1. I appreciate your help!

a00.snjsca03#sh ip int brief

Interface IP-Address OK? Method Status Protocol

Vlan1 YES NVRAM up up


Here's the config:

interface FastEthernet0/2/2

duplex full

speed 100


interface Vlan1

ip address


Here's the routing table:

Gateway of last resort is not set is subnetted, 1 subnets

C is directly connected, Vlan


Here's sh vlan-switch output:

VLAN Name Status Ports

---- -------------------------------- --------- -------------------------------

1 default active Fa0/2/1, Fa0/2/2, Fa0/2/3



New Member

Re: Virtual Interface Routing Issue

Looks like I have a bad slot on my router. Things work fine if I terminate the ethernet cable into my other 4 port ESW.

Thanks anyway Glen!