Re: [Sigtran] Clarify SCTP max packet size.

["Brian F. G. Bidulock" <bidulock at openss7.org>]

Michael,

Err, the MTU SCTP uses when bundling is the Association Path MTU.  It
subtracts IP header and SCTP header sizes from this Path MTU only when
considering how many chunks can be bundled.

--brian

Michael Tüxen wrote:                        (Tue, 07 Jul 2009 18:51:09)
> On Jul 7, 2009, at 8:50 AM, <pierre.allegret at orange-ftgroup.com> 
> <pierre.allegret at orange-ftgroup.com > wrote:
> 
> >Dear all,
> >
> >Just to add with the SCTP bundling feature. If the "SCTP MTU" is  
> >1500, and the system is bundling messages at the SCTP level, you  
> >should have the risk to segment at the IP level (because of the IP  
> >header). So it is not efficient
> The MTU SCTP uses is the link layer MTU minus the headers for IP and  
> SCTP.
> I have not seen an implementation which bundles at the SCTP layer and  
> than
> needs to fragment at the IP layer. I would consider this broken...
> >to bundle sctp messages and to segment them at the IP level. Some  
> >vendors limits "SCTP MTU" to avoid that. This is only the Maximum  
> >transmission unit. If one SCTP message to transmit is greater, they  
> >will segment it.
> >

-- 
Brian F. G. Bidulock
bidulock at openss7.org
http://www.openss7.org/