9.3. Traceroute Using Mixed Locators

9.3. Traceroute Using Mixed Locators

When either an IPv4 traceroute or IPv6 traceroute is originated and the ITR encapsulates it in the other address family header, one cannot get all 3 segments of the traceroute. Segment 2 of the traceroute cannot be conveyed to the traceroute source, since it is expecting addresses from intermediate hops in the same address format for the type of traceroute it originated. Therefore, in this case, segment 2 will make the tunnel look like one hop. All the ITR has to do to make this work is to not copy the inner TTL to the outer, encapsulating header's TTL when a traceroute packet is encapsulated using an RLOC from a different address family. This will cause no TTL decrement to 0 to occur in core routers between the ITR and ETR.