[xcp] Embedding XCP signalling in IP header

Marko Zec zec at icir.org
Thu Aug 19 03:50:39 PDT 2004


On Thursday 19 August 2004 00:36, Marko Zec wrote:
> On Wednesday 18 August 2004 20:56, Tim Shepard wrote:
> > I've also heard that some VPN tunnels ignore the DF bit and fragment
> > anyways.  (I believe this was mentioned in the pmtud WG at IETF60.)
>
> Well, wouldn't that mean those VPN tunnels are violating the standards? And
> how are end hosts supposed to reassemble such fragments, if they have DF
> flags set? That would have to be another undocumented / non-standard
> feature on host IP stacks.


Ugh I just saw what I previously wrote and certainly it was plain wrong - of 
course hosts will try to do reassembling regardless of the DF flag state. But 
that still doesn't mean those VPN tunnels you've mentioned (which are 
ruthlessly fragmenting packets with DF flag set) should be considered legal.

Marko


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