Monday, November 18, 2013

Error Of the Day - Static Route from Global RT to a Loopback Interface On The Same Router - VRF Leaking

This Message was Generated after i configured a static route from the global routing table pointing to a loopback interface in a VRF.

this is a snippet from the configuration of the same router

ip vrf a
 rd 100:1
 route-target export 100:1 route-target import 100:1
interface Loopback0
 ip address !
interface Loopback10
 ip vrf forwarding a
 ip address
ip route loopback10

Now when i try to ping from lo0 in the global routing table to loopback10 in vrf a

*Nov 18 22:14:12.067: %IP-3-LOOPPAK: Looping packet detected and dropped -
src=, dst=, hl=20, tl=100, prot=1, sport=0, dport=0 in=Loopback10, nexthop=, out=Loopback10
options=none -Process= "IP Input", ipl= 0, pid= 97,  -Traceback= 0x61ECB070z 0x61ECC2B4z 0x61ECD200z 0x61ECD63Cz 0x61ECD9FCz 0x61EB6780z 0x61EB71B4z 0x61EB7638z 0x61EB772Cz 0x61EB7980z 0x6339B980z 0x6339B964z

The funny part is even though Cisco allowed you to configure that static route and didn't generate an error while configuration. But what's interesting is that the source packet is although it should've been of lo0 in the GRT

Feel free to drop a comment regarding this issue :)

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