IP over SONET considered harmful?

Fri Mar 20 21:41:36 UTC 1998

Paul E. Erkkila writes:
>	Without going to far into the traceroute source , would
>  a solution to this problem be a modified traceroute that 
>  "understood" and could report Tag/MPLS "hops" as well as
>  the normal method? There would need to be some way of
>  identifying which devices were forwarding using Tag/Mpls
>  and which were not, as well as getting and reporting
>  the information. I think it falls into the same category of
>  tracing cell forwarding in ATM without having access to the
>  equipment doing the work.

Without getting into whether this is a good idea - I suspect many
service providers would disable such a capability - one of the nice
aspects of traceroute is that it uses the usual packet forwarding path
until the last hop. In other words, it's a little hard to break the
normal packet forwarding mechanism without breaking traceroute too.
This charcteristic would be hard to preserve with such a solution.

>	Alan and I discussed the "knob" solution before, it seems
>   to solve the problem, but under certain circumstances a packet 
>   could end up being forwarded forever because of (mis)configuration.

You do have to make sure that tunnels always move packets closer to
their destination, yes.