Strange public traceroutes return private RFC1918 addresses

Tue Feb 3 10:47:52 UTC 2004

>Which (as discussed previously) breaks things like Path MTU Discovery, 
>traceroute, 

If RFC1918 addresses are used only on interfaces with jumbo MTUs
on the order of 9000 bytes then it doesn't break PMTUD in a
1500 byte Ethernet world. And it doesn't break traceroute.
We just lose the DNS hint about the router location.

A more important question is what will happen as we move out
of the 1500 byte Ethernet world into the jumbo gigE world. It's
only a matter of time before end users will be running gigE
networks and want to use jumbo MTUs on their Internet links.
Could we all agree on a hierarchy of jumbo MTU sizes that 
with the largest sizes in the core and the smallest sizes at
the edge? The increment in sizes should allow for a layer or
two of encapsulation and peering routers should use the
largest size MTU.

Thoughts?

--Michael Dillon