[f-nsp] RSVP signaled MTU on XMR?

[Kevin Hodle]

Hi Richard,

   Yes, indeed I do have path-mtu rsvp mtu-signaling configured on the 
Junipers. In fact, I have another LSP for the other direction with the 
Juniper acting as ingress, and it seems to signal the path MTU correctly 
(sends it's interface MTU of 4470 in the Adspec object).


Richard A Steenbergen wrote:
> On Thu, Jan 17, 2008 at 11:45:46AM -0500, Kevin Hodle wrote:
>> 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 :)
> 
> I don't think that 1500 is an offical default according to the spec, but 
> Juniper seems to use it as such if you don't configure RSVP path-mtu 
> signaling.
> 
> http://www.juniper.net/techpubs/software/junos/junos84/swconfig84-mpls-apps/id-13749.html
> 
> Specifically:
> 
> A Juniper Networks transit router that does not support MTU signaling in 
> RSVP always propagates an MTU value of 1500 in the Adspec object.
> 
> Foundry might do something similar, though I can't actually find any 
> Foundry command to show the Adspec Path MTU. You do have protocols mpls 
> path-mtu rsvp mtu-signaling configured on both of your Juniper's right? :)
> 

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