The MPLS WG Archive

["Arvind, K" <arvind@tenornetworks.com>]

	David:

	>The maximum size for most RSVP messges is the interface's MTU size,
	>since an RSVP message must fit entirely into a single
non-fragmented IP
	>datagram.

	According to RFC2205, Section 3.3:

	"In this version of the spec, each RSVP message must occupy exactly
one IP datagram. If it exceeds the MTU, such a datagram will be fragmented
by IP and reassembled at the recipient node. This has several consequences:
	o A single RSVP message may not exceed the maximum IP datagram size,
approximately 64K bytes.
	o A congested non-RSVP cloud could lose individual message
fragments, and any lost fragment will lose the entire message.

	Future versions of the protocol will provide solutions for these
problems if they prove burdensome.
	"

	The paragraph quoted above doesn't seem to mandate that "an RSVP
message must fit entirely into a single non-fragmented IP datagram"(I
interpret "non-fragmented ip datagram" to mean one which is less than MTU) ,
though it does point out the potential practical consequences of
fragmentation. I don't remember seeing any explicit prohibition of
fragmentation in the RSVP-TE spec. Did I miss something?

	>The one exception is a bundle message (one of the RSVP extensions
in RFC
	>2961).  Bundle messages may be as large as an IP datagram, since
they
	>may be fragmented.  This means a maximum size of 64K.

	RFC2961 states explicitly that both Srefresh and Bundle messages may
be IP fragmented,

      Regards,
      Arvind.


> -----Original Message-----
> From:	David Charlap [SMTP:david.charlap@marconi.com]
> Sent:	Wednesday, June 13, 2001 9:12 PM
> To:	mpls@UU.NET
> Subject:	Re: MAX rsvp-te message size
> 
> Hong Liao wrote:
> > 
> > Hi,
> > 
> > Can anyone tell me the max size of RSVP-TE message sent out?
> > 
> > I saw cr-ldp spec, the max size for cr-ldp is 4096 bytes.
> > 
> > Thanks in an advance.
> 
> The maximum size for most RSVP messges is the interface's MTU size,
> since an RSVP message must fit entirely into a single non-fragmented IP
> datagram.
> 
> The one exception is a bundle message (one of the RSVP extensions in RFC
> 2961).  Bundle messages may be as large as an IP datagram, since they
> may be fragmented.  This means a maximum size of 64K.
> 
> -- David