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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 problem is that the user is unable to ping from CE1 to CE2 (192.168.1.196). The reason for this is
because we have manually created an LSP Blackhole between the P router, which in this case is the GSR,
and PE2. This has been manually configured in the running-config for PE2 by specifying a loopback
address for PE2 to be:
• interface Loopback0
–
ip address 10.5.5.5 255.255.255.0
–
no ip directed-broadcast
Analysis of Problem
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 from the dialog, there is no out-going label for 10.5.5.5. When the packet leaves PE1 it
carries two labels, the BGP next hop label generated by the P router (12307) and the VPN label generated
by PE2.
Figure C-2 Example MPLS Forwarding Information Window