PMTU Discovery support

[Kevin Lahey]

On Tue, 20 Mar 2007 01:47:27 +0000
"Bruce M. Simpson" <bms at FreeBSD.org> wrote:

> I believe PMTU measurements may only be relied upon for active TCP 
> connections, but it's been a while since I read this code.

I think, according to RFC1191, that the probing should happen on any
given connection after 10 minutes.  Otherwise, a single ICMP message
could permanently reduce the MTU of a connection for good.  I believe
that FreeBSD and others did it that way 10 years ago, when I did a
survey of available PMTUD implementations.

I wonder if all applicable TCP connections ought to be notified when
the hostcache MTU is updated and when a hostcache entry with an MTU
set is deleted? (For that matter, can an entry ever be deleted while
outstanding connections are going to that host?)

Kevin
kml at patheticgeek.net