[f-nsp] RSVP signaled MTU on XMR?

[Kevin Hodle]

Greetings f-nsp,

    I am testing a fairly simple 3 node RSVP signaled LSP topology 
looking like this:

(ingress/XMR)--(transit/Juniper)--(egress/Juniper)

If my understanding of the RFC is correct, the XMR acting as the ingress 
LER should be able to specify a desired MTU when signaling the LSP 
setup. We are utilizing the 'ipmtu' statement within the LSP definition 
on the XMR as follows:

lsp test_lsp
   to 192.168.1.6
   from 192.168.1.7
   primary test_path
   ipmtu 4470
   enable

However when looking at 'show mpls lsp detail' on the transit and egress 
routers, i see an MTU of 1500 sent in the Adspec object:

192.168.1.6
   From: 192.168.1.7, LSPstate: Up, ActiveRoute: 0
   LSPname: test_lsp
   Suggested label received: -, Suggested label sent: -
   Recovery label received: -, Recovery label sent: -
   Resv style: 1 FF, Label in: 3, Label out: -
   Time left:  137, Since: Fri Jan 11 17:45:26 2008
   Tspec: rate 0bps size 0bps peak 0bps m 20 M 1500
   Port number: sender 1 receiver 14 protocol 0
   PATH rcvfrom: 192.168.1.93 (so-0/0/0.0) 12002 pkts
   Adspec: received MTU 1500
   PATH sentto: localclient
   RESV rcvfrom: localclient
   Record route: 192.168.1.49 192.168.1.93 <self>

Foundry support has indicated that the 'ipmtu' statement in the LSP 
definition is only relevant to the local router and that they do not 
support RSVP signaled MTU at this time. The problem here is that there 
are no interfaces in the path between the ingress & egress with an MTU 
of 1500, so I have no idea where it is getting this value from. Is this 
a default value that can be changed? I would hate to think that this 
value is somehow hard coded :)

This is on an XMR 4k running 3.5c code.

Any input or experiences you guys have had with this would be appreciated.

Regards,

-- 
|| Kevin Hodle, WAN Team
|| 1&1 Internet Inc.
|| 10950 Strang Line Rd, Lenexa, KS 66215, USA
||
|| (610)-560-1637 (Voice)  (610) 560-1631 (fax)

PGP key    | fingerprint
0xBBDE8ED7 | 3E1B 1F10 938E A831 8CF2 670C 1329 0B8B BBDE 8ED7