Cisco 2821 15.1.3(T4) Multicast Tun0 int not formed for second VRF


[H]F Junkie
Mar 31, 2001
Hey Guys,

I have a Cisoc 2821 (rescued from the garbage) in my lab with 2 physical interfaces. We'll call this router "P"

Each physical interface on router "P" has no config, but has 3 802.1q under it and is plugged into a switch that allows trunking to these vlans. All BGP/routing/unicast works as expected between router "P" (simulated provider) and router "E" (simulated customer - our on-site router)

On router P (interfaces Gi0/0, and Gi0/1)

Gi0/0 has no config but Gi 0/0.1, Gi0/0.2, Gi0/0.3 all have config and are assigned to vrf "c"
Gi0/1 also has no config but Gi0/1.4, Gi0/0.5, Gi0/0.6 all have config & are assigned to vrf "s"

I've got these 2 vrfs to emulate 2 provider networks. Both vrfs run BGP & multicast (pim sparse mode, with autorp)

Gi0/0.1 goes to router E and does BGP
Gi0/1.4 also goes to router E and does BGP

As far as router E is concerned, it's talking to 2 different networks.

Multicast routing is turned on for both vrfs (Router P) & config is the same for both. Auto RP is also enabled as is pim-sparse mode for both interfaces on router E as well as router P.

vrf c works great & it finds the RP.
vrf s never finds an RP.

I've shut down the working vrf c parent interface (Gi0/0) just incase it was some RPF bug or something, but it still doesn't work.

Anyone seen this? I'm almost convinced this is a bug...
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Limp Gawd
Mar 18, 2016
not sure of your IP scheme, but try "ping vrf <vrf instance> <ip address>" for both, and see if it's what you're expecting, also examine your routing tables "Show ip route vrf <vrf name>" and see if the routes are what you're expecting