The MPLS-OPS Archive

[Spice Sylvia <falsesylvia@yahoo.co.uk>]

Hi,


> 
> If you will only ever have one LSP across your core,
> I agree that hierarchy doesn't save you much
> (although the technology boundaries may still make
> it desirable so that (e.g.) you odn't have to look
> at packets on a lambda router.
> 
> The saving comes when you have bulk parallel LSPs
> across the core. That ain't stitching.
> 
> (NB. Some people like to see stitching as a special
> case of 1:1 hierarchy without label stacking. I
> wouldn't like to comment :-)

Exactly, if I dont have something "changing" what is
wrong with statically provisioning once and for all.

> 
> Your figure is perhpas a rather simplistic network.
> Let us insert a whole network cloud between N2 and
> N3 so that the hierarchical LSP runs
> N2,n1,n2,n3,n4,N3.
> N2 will allocate a single lambda to reach N3.
> This lambda will carry all of the traffic from N1 to
> N4 and from N5 to N6.
> The traffic at N3 is easily discriminated so that it
> can be sent to N4 or N6. But within the core network
> (at the nx nodes) only one lambda needs to be
> switched.

Ok so we are building a "hierarchy of lambdas". At the
same time, how is this different from the statically
provisioned thin pipes of colored water pour into a
thick pipe analogy? As long as the thick pipe does not
have demuxing capabilities of each individual/or some
subs of thin pipes, it does nothing but carry all
water from here to there.

Similarly is there any resource that needs to be
"signalled" in this? I an understand signalling Call
Parameters as they are dynamic and unique per call,
but what basically confuses me is the aspect of
"signalling" when a resource cannot do any dynamic
allocation. (even in terms of lambdas/space matrix
switching, we are not looking at moving links
dynamically across ports, are we?)

> There is no difference in effect between a manually
> provisioned LSP and an LSP provisioned by the
> control plane. The purpose of a control plane is
> well discussed elsewhere, but includes dynamic
> utilisation of resources (so that the core can have
> resources that are used for different purposes at
> different times), dynamic provisioning (to simplify
> the management plane interactions), and
> responsiveness to network utilisation and faults (to
> allow repair and recovery as well as optimization).
> 
But a node with switching an no TE capabilities can
never fall in the category of being able to perform
"dynamic utilization of resources".


> Now it may be that you asking (subtly) how and when
> the FA LSP is provisioned. Is it triggered when the
> first LSP tries to cross the core? Is it
> pre-provisioned through management planning? Are new
> FA LSPs added automatically when load increases?

Agreed, now how do I add "lambdas" automatically?

Either we have a "waveguide/channel" or we dont. The
purpose of signalling here beats me.


> 

> 
> Yes!
> You can see the core network as a giant (virtual)
> cross connect. This is one of the models used to
> provide layer 1 VPN services.
> 
Yes, but only if I assume it is a pipe with "no
participation in TE from the edge's perspective".

Just like the router over TDM overlay. As far as the
end routers go, and from the signalling plane
perspective, the 2 links are as good as one "fat
conduit" between 2 nodes, if we assume that the TDM
network cannot participate in signalling.


I am still no grasping what is the element "which
needs to be programmed by the signal" when a node has
no TE properties.
-brgds
Sylvia

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