Cisco Systems 12000/10700 V3.1.1 manual Solution, Local Outgoing Prefix Bytes Tag Next Hop

Appendix C Investigating LSP Black Holes Using Cisco 12000 Series Router Manager

Setup

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:

Table C-1 Example Output

Local	Outgoing	Prefix	Bytes Tag	Outgoing	Next Hop
tag	tag or VC	or Tunnel Id	Switched	Interface
12307	Untagged	10.5.5.5/32	365	Gi1/0	10.8.8.5

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 Example MPLS Forwarding Information Window

Cisco 12000/10700 v3.1.1 Router Manager User Guide

OL-4455-01 C-3