paket fragmentation and mtu

[Stephan von Krawczynski <skraw,AT,ithnet,DOT,com>]

Hello all,

the everlasting topic of mtu and paket fragmentation hit me again :-)
I currently have a cipe-connection up and running with internet on one side 
(cipe 1.4.3) and
windows clients on the other (internal) side (cipe 1.5.2).
I am currently not able to see webpages from certain sites (e.g. 
www.elsa.de), because
of an obvious problem with mtu/fragmentation.
During several tests I found out, that everything _should_ be ok, if these 
sites would not
send TCP-pakets with "Dont fragment" bit set. The length of the paket itself 
seems no
problem (1500 bytes of course), because I can ping them with the same paket 
length.
This is ridiculous. The pakets arrive at the cipe-router and it does not 
forward them, because
it cannot fragment them. Does anybody have any idea how to solve this? 
I tried of course: cipe mtu 576, 2048, 4096 on both sides. Does not work.

Weird question, but: is there a way to ignore the "dont fragment" bit somehow?

Regards,
Stephan