C-2
Cisco 12000/10700 v3.1.1 Router Manager User Guide
OL-4455-01
Appendix C Investigating LSP Black Holes Using Cisco 12000 Series Router Manager
Setup
•P—PE2 :Gigabit Ethernet
•PE2—CE2 : POS
Problem
The prob lem is t hat the us er is unab le to ping fro m CE1 to CE 2 (19 2.1 68.1. 196 ). Th e re aso n f or this is
becau se we hav e manu ally create d an LSP Blackho le between th e P router , w hich in thi s case is the G SR,
and PE2. T his ha s bee n manua ll y con figured in the runni ng- config f or PE2 by sp ec ifyi ng a lo opba ck
address for PE2 to be:
•interfac e Loopb ack0
–
ip add re ss 1 0.5 .5 .5 255 .255. 255 .0
–
no ip dire cted- broad cast
Analysis of P rob lem
The LSP Black Hole can be easily displayed when you select the P router, and launch the MPLS
Forwarding Information window. This can be found on the pull-right menu of the chassis, under Fault>
MPLS> MPLS Forwarding Information.
As can be seen fr om the dia log, th ere is no ou t- goin g la be l for 10 .5.5. 5. Whe n th e packet le aves PE1 it
carries two labels, the BGP next hop label generated by the P router (12307) and the VPN label generated
by P E2.
Figure C-2 Example MPLS Forwarding Information Window