[j-nsp] fragmentation in GRE tunnel

[Dan Rautio]

Hi Ruslan,

This knob will prefragment the packets before GRE to avoid reassembly on
the other side.  One caveat of this feature is it works only on IP
traffic, not mpls.  Another caveat is reassembly at the end of the GRE
tunnel is not yet officially supported.

Some work-arounds would be to:

- use 'vrf-table-label' if a VRF is involved in your topology.  In that
way the mpls label would be popped off and then GRE prefragment would
work on the exposed IP packets.

- even uglier, use mpls+gre+ip-ip encapsulation


- Dan

> -----Original Message-----
> From: Ruslan A. Magomedov [mailto:magpack at retn.net] 
> Sent: Friday, May 04, 2007 2:10 AM
> To: Dan Rautio
> Cc: juniper-nsp at puck.nether.net
> Subject: Re: [j-nsp] fragmentation in GRE tunnel
> 
> 
> Hi Dan
> 
> So using an AS PIC packets will be reassembled at the end of a
> tunnel and there are no problems with MPLS traffic also?
> 
> Thank you for your reply
> 
> Best regards
> Ruslan
> 
> Thu, 3 May 2007 21:09:51 -0700
> "Dan Rautio" <drautio at juniper.net> wrote:
> 
> > Hi Ruslan,
> > 
> > M-series tunnel pic there is no way to do what you want.  
> You can use
> > the 'clear don't fragment' option on the m-series although 
> it requires
> > an AS pic.
> > 
> > - Dan
> > 
> > > -----Original Message-----
> > > From: juniper-nsp-bounces at puck.nether.net 
> > > [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of 
> > > Ruslan A. Magomedov
> > > Sent: Thursday, May 03, 2007 10:11 AM
> > > To: Juniper Request Help List
> > > Subject: [j-nsp] fragmentation in GRE tunnel
> > > 
> > > 
> > > Hello
> > > 
> > > Could anybody help me with resolving this problem. Is it possible
> > > to transmit packets, then tunnel MTU is greather than MTU 
> of egress
> > > interface, in other words using only GRE fragmentation (not ip
> > > fragmentation). I have tried it on Juniper M-series with 
> tunnel PICs
> > > and have got no result. It looks like router does not reassemble
> > > GRE packets, but it's doing fragmentation on egress 
> > > interface. Is there
> > > any acceptable solution to transmit large packets with out using
> > > ordinary IP fragmentation. The final aim is transmitting of 
> > > MPLS traffic
> > > over GRE tunnel without limitations due to MTU value of 
> > > transit network
> > > 
> > > Best regards
> > > Ruslan
> > > _______________________________________________
> > > juniper-nsp mailing list juniper-nsp at puck.nether.net
> > > https://puck.nether.net/mailman/listinfo/juniper-nsp
> > > 
>