MTU handling in 6RD deployments

[Templin, Fred L]

> cache a boolean "ACCEPTS_BIG_PACKETS" for this CE.

BTW, the reason I am saying that the only thing we are trying
to determine is whether/not the CE<->BR path can pass a 1500
byte packet is that 1500 bytes is the de facto Internet cell
most end systems expect to see w/o getting an ICMP PTB back.

So, if we can give the hosts at least 1500 then if they want
to try for a larger size they should use RFC4821. This makes
things much easier than trying to probe the CE<->BR path for
an exact size.

Thanks - Fred
fred.l.templin at boeing.com