Juniper Contrail – how to check Next-Hop

One might need to check which MPLSoGRE/UDP/VXLAN tunnel is used to reach a specific prefix on a vrouter.

There are few steps needed to find it out after logging in to a compute node running a VM/contrainer with an interface of interest (its prefix or prefix reachable via it) :

    1. List all interfaces and see which vrouter VRF a specific interface maps to:

    2. Use the VRF id to dump routes in a routing table for this VRF and check a prefix in question and its next-hop id:

    3. Check next-hop id parameters with:

SDN course for free on

There is a great SDN introductory course available on run by Dr. Nick Feamster from Princetone University. Enroll on current session – but in order to get a certificate of course completion tasks must be followed weekly for 8 weeks in a row. Now a 3rd week has just started so there is still some space to catch up as later on it might be too late.