I have been trying to guess the syntax but, I can't figure out how to do it

enter image description here

Based on the above diagram, what should be the traceroute command on R1 to force the traffic go via R1->R2->R4?

1 Answer 1


Based on the comments, you need source routing enabled on the routers. It is disabled by default for security reasons, and the routing options in a packet will be ignored if source routing is disabled.

Your host must supply the route options in the path. You can use Cisco's extended traceroute to specify the route options, but it will not work unless you have source routing enabled on all the routers in the desired path.

This also forces traffic to be process switched, and this will slow routing. If your desire is to test propagation times, you will find they are slower with source routing.

Once you have finished testing, you should disable it. Your network design is fairly meaningless if the hosts determine the path which traffic will take, and it is a security problem. You are unlikely to find any businesses or Internet carriers/providers which have this enabled.

You can use the extended traceroute. Something like:

Protocol [ip]: 
Target IP address:
Ingress traceroute [n]: 
Source address:
Numeric display [n]:
Timeout in seconds [3]: 
Probe count [3]: 
Minimum Time to Live [1]: 
Maximum Time to Live [30]: 
Port Number [33434]: 
Loose, Strict, Record, Timestamp, Verbose[none]: Loose
Source route:

Cisco has documents explaining this command, e.g. Using the Extended ping and Extended traceroute Commands. You can search for cisco extended traceroute on the Internet.

  • Thanks Ron, your comments are valid but they do not address the question. The Cisco CLI allows you to do this; one use case scenario would be to test a path (propagation times) before you switch the traffic through that path.
    – MiniMe
    May 6, 2016 at 20:09
  • You can enable source routing in some Cisco routers, but your host will need to supply the route options, and you can be quite disappointed with the results since it often doesn't work as expected. It is dangerous to leave it enabled.
    – Ron Maupin
    May 6, 2016 at 20:16
  • I am asking here about using the traceroute command with the strict source routing option. Are you suggesting that I need to enable source route routing before I use this?
    – MiniMe
    May 6, 2016 at 20:18
  • Yes. The route options in a packet will be ignored with source routing disabled on the routers.
    – Ron Maupin
    May 6, 2016 at 20:23
  • OK I get it I will enable the source routing on the routers but then how do I force the packets to take the path I want using the traceroute command available via Cisco CLI
    – MiniMe
    May 6, 2016 at 21:46

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.