MTU path discovery and IPSec

Arjan Hulsebos ahulsebos at
Thu Dec 4 18:18:45 UTC 2003

> On Wed, 03 Dec 2003 16:05:39 GMT, jgraun at  said:
> > 1) I assume MTU path discovery has to been in enabled on 
> each router in the path in order for it work correctly?!
> Actually, no.  All that's required is that:

You also need an OS that does not set the DF-bit on every packet it sends
out. IIRC, out-of-the-box Solaris 8 is excellent at doing that. No matter
how many icmp messages it gets, it happily ignores them by insisting on
sending out frames of 1500 bytes with the DF-bit set. Makes trouble-shooting
IPSec connections, uhm.... interesting.


Arjan H

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