ISIS Single Topology strange behavior
For CCIE-SP Workbook lab problem 2.17 "Single Topology IS-IS" where you issue the “traceroute 18.104.22.168” and “traceroute 2001::20:20:20:20” command from R1 to XR2, the result should be that IPv4 and IPv6 traffic must follow the same path throughout the network as the shortest Path Tree for each of them are the same. This seems to be true when issuing the traceroute command from R1 to XR2 (with the condition that no ISIS process ID (null) is used for regular IOS. For some reason when I use a number for a process id it does not work as it should), but when you try to do a traceroute from XR2 to R1 (22.214.171.124, 2001::1:1:1:1) in the other direction, it does not follow the same path......ipv4 goes through R5 and ipv6 goes through R6. If you do the same traceroute from XR1 to R1 (126.96.36.199, 2001::1:1:1:1) it follows the same path correctly as it should. Is this a bug?