Troubleshooting and Verification 83

Type escape sequence to abort.

Tracing the route to 192.168.2.1

1 192.168.3.6 16 msec 16 msec 16 msec

2 204.134.83.6 48 msec 48 msec 48 msec

3 204.134.83.10 44 msec 44 msec 44 msec

4 192.168.3.10 [AS 65002] 60 msec * 60 msec

Hiding Service Provider Devices

In the previous section, I executed a traceroute command where all the service provider devices showed up in the traceroute output. To hide service provider devices, you need to execute the no tag-switching ip propagatettl on every device in the service provider network. Once this command is enabled on each and every service provider router, a client only sees the ingress and egress PE routers, not all the P devices. The required configuration for the troubleshooting network is as follows:

Core#conf t

Enter configuration commands, one per line. End with CNTL/Z. Core(config)#no tag-switching ip propagate-ttl

Raleigh#conf t

Enter configuration commands, one per line. End with CNTL/Z. Raleigh(config)#no tag-switching ip propagate-ttl

Atlanta#conf t

Enter configuration commands, one per line. End with CNTL/Z. Atlanta(config)#no tag-switching ip propagate-ttl

The MPLS version of this command is no mpls ip propagate-ttl.

The output of the traceroute command on Peer 1 to the loopback of Peer 2 is as follows:

Peer1#traceroute 192.168.2.1