[OpenAFS] Network becomes terribly slow when cache manager flushes updates over xDSL

Mattias Pantzare pantzer@ludd.ltu.se
Wed, 8 Jul 2009 19:24:56 +0200

On Wed, Jul 8, 2009 at 19:06, Carson Gaspar<carson@taltos.org> wrote:
> Sean O'Malley wrote:
>> -icmp shouldn't be used. Some BOFH block/drop icmp.
> ...
>> -is there a standard way to do UDP mtu link detection on any platform
>> already?
> The standard is ICMP WOULD FRAGMENT. People who block that don't deserve
> functional apps. Don't cater to them.

The end user seldom have control over all firewalls...

There are two goos solutions to this problem, one is to start using
TCP for AFS as these problems are solved in good TCP implementations.

The other solution is to look at how a good TCP implementation handles
path mtu discovery, including black hole detection (when the wold
fragment icmp packets are dropped) and copy that.