Long hops on international paths

Mark Tinka mark at tinka.africa
Tue Jan 18 15:23:02 UTC 2022


On 1/18/22 16:28, Saku Ytti wrote:

> 2) MPLS-TTL expires in transit
> 2a) generate TTL exceeded and put it back to tunnel, sending it to
> egressPE, which is guaranteed to know how to return to sender

This is what we run - our core is BGP-free (LDP), so the traceroute 
value customers see will be the egress PE router.

> 2nd best is to tunnel, but the
> RTT will confuse uneducated, or as it may be, hjghly educated, users.

It is very confusing, even for some educated users.

It's become less of problem, as years of educating users seems to have 
bedded in.

> We could implement something like
> https://ytti.github.io/icmp-eo-timestamp/draft-ytti-intarea-icmp-eo-timestamp.html
> to offer correct forward latencies to P/LSR in 2a scenario.

I recall you and I chatted about this some 3 or so years ago. Do you 
know if anyone of the (un)usual suspects have implemented?

Mark.



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