Solution - Cisco 12000 User Manual

Appendix C Investigating LSP Black Holes Using Cisco 12000 Series Router Manager
The entry on the P router shows untagged, so label-switched packets for this destination will be sent out
without any labels. Since the VPN label was lost, it will never be received by PE2, and PE2 will not have
the correct information to forward the packet to the proper VPN destination.
This information is the same as that displayed when the following Cisco IOS command is executed:
show mpls forwarding-table
The output you see is as shown in
Table C-1 Example Output
Local Outgoing
tag tag or VC
12307 Untagged

Solution

There are several solutions to this problem, and the easiest is to change the sub-net mask for the loopback
address on PE2 to 255.255.255.255, from 255.255.255.0.
When you do this, and refresh the MPLS Forwarding Information window, or wait for it to manually
update, you now see:
Figure C-3
OL-4455-01
Table
Prefix
or Tunnel Id
10.5.5.5/32
Example MPLS Forwarding Information Window
C-1:
Bytes Tag Outgoing
Switched Interface
365 Gi1/0
Cisco 12000/10700 v3.1.1 Router Manager User Guide
Setup
Next Hop
10.8.8.5
C-3