The MPLS WG Archive

[Toby Smith <tob@laurelnetworks.com>]

Giles Heron <giles@packetexchange.net> writes:

> Narasimha Swamy wrote:
> > 
> > Hi,
> > In case of L2VPN sessions configuration, it is possible for an edge LSR to
> > receive unmatched MTU or vc-type from other edge LSR for a particular l2vpn
> > session.
> 
> By L2VPN here do you mean draft-martini?
> 
> If so then yes - it is possible for the edge LSR to receive unmatched
> MTU or vc-type from the peer edge LSR.
> 
> > What type of message should be sent in this case to indicate this error. If
> > notification message is sent, what will be the Status Code.
> 
> A label release should be sent.

Hi,

Are you sure about this last bit?  If one LSR has a configured MTU of
1400, and receives information from its peer for the same VC ID &
interface type, but with an advertised MTU of 1500, I would think that
this situation would be better served by maintaining the received
mapping and relaying this status to the local user, who has a better
chance of configuring the local interface to a matching MTU (or fixing
things up on the remote side).

If a release is sent instead, it then opens up the issue of having the
LSR who issued the release later send a request for that mapping.

Either that, or the remote LSR who receives the release from the local
LSR now has enough information to pick a new MTU that might be more
amenable to the LSR which sent the release.  But now we're talking
about MTU negotiation, aren't we.

Regards,
Tob