Sun, May 19, 2002 at 12:32:08PM -0700, Wolfgang Rupprecht:
> 
> The examples in the source were from the days when it was unusual for
> routers to do the TTL decrementing for ICMP messages correctly.
> Traceroute was the tool that caused folks to fix these bugs.
> 
> I can't recall a single case within the last few years where I did a
> traceroute and saw a "hole" of 5 or more hops.

iirc, this could easily occur where a MPLS LSP exchanges the MPLS and IP
on push/pop and decrements the ttl per-MPLS-hop while the standards
dictate that an LSP should not return ttl-expired icmp's.
so, should an LSP exist between say .au and new york, its likely to have
more than 5 MPLS hops and you wouldnt rx icmp's for the hops within the
LSP.