The MPLS WG Archive

["Dominic-Savio, Patrick" <Patrick.Dominic-Savio@marconi.com>]

Hi,
The description for mplsTunnelResourcePointer indicates that 2 or more
segments can share resources if the user specifies the same value for this
object for different tunnels.

The description for mplsTunnelSessionAttributes:mergingPermitted indicates
that this is used for reducing resource overhead on downstream transit
routers.

I'm a bit confused about how these two parameters are related (if they are
indeed related). 
First off I'm assuming that mplsTunnelSessionAttributes:mergingPermitted
corresponds to the "SE Style desired" flag of the RSVP Session Attribute
Object [RFC3209] when RSVP is used for signalling. If this is the case then
this bit does not "permit transit routers to merge this session..." it is
only an indication to the egress LSR requesting SE style of reservation.
In any case could you confirm that the
mplsTunnelSessionAttributes:mergingPermitted value does correspond to the
"SE Style desired" flag in RSVP.

If my above assumption is correct then (again with RSVP), say the user sets
up a couple of tunnel instances and requests SE style reservation (using the
mergingPermitted flag) for them. Now, if the egress LSR honors the request
and responds with a SE STYLE reservation, shouldn't the ingress LSR (along
with the transit LSRs) share resources between these two instances ?.
So, receiving of an SE STYLE reservation by itself should indicate to the
ingress LSR that resources should be shared. What then is the purpose of
indication of resource sharing by specifying the same value of
mplsTunnelResourcePointer on the ingress LSR?, this appears to be redundant.

Thanks
-patrick.

---------------------------------------------------------
Patrick Dominic-Savio


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