[6bed4-devel] Anycast addresses and debugging.

[<ebi...@xm...>]

There are two issues that using anycast addresses can trigger that both
impact debugging, and until I had those two issue conflated.

- Anycast addresses are a good way to trigger assymetric routing.
- Anycast addresses hide which machine is the router in your path.

Assymetric routes can happen with ipv4 and they are a pain, because
getting a reverse traceroute requires tracing from the other side.

Having multiple routers at very different places in the network
operated by different people report the same address in traceroute
makes figuring out who to blame for slow traffic a real challenge.

So I suggest adding:  "ICMP time exceeded errors MUST NOT be reported
with a 6bed4 address."  to make it possible to figure out whose 6bed4
router is malfunctioning.

Eric