The MPLS WG Archive

[Zhi-Wei Lin <zwlin@lucent.com>]

Hi Kireeti,

I agree that the judge of relevancy is the SPs. The SPs will tell us
(vendors) what their business models are, and what we need to support
first. 

In your example, you suggest that a router is setting up diverse paths
for protection without the service provider knowing about this. Is the
router part of the service provider network or part of the customer
network?

What is the reason for requesting those two diverse paths? Is it to meet
some availability requirement? Or is it for something else?

Thanks in advance for your clarification.

Zhi


Kireeti Kompella wrote:
> 
> > I don't see why TE and protection require the routers to specify explicit
> > routes.
> > The routers can simply specify to the optical layer what type of optical
> > layer protection
> > it requires.
> 
> Suppose router A wants to get to router B, and wants to take two
> different ingress and egress points in the optical domain, X->Y
> for the primary LSP, and W->Z for the backup.  A does not require
> optical protection for the X->Y path, nor for the W->Z path.  A
> *does* require that the X->Y path and the W->Z path do not share
> common links.  How is this to be done?
> 
> If A did the full path computation, this is simplicity itself.
> 
> > Based on its traffic flow a router only needs to know between
> > which
> > two routers it needs to establish a new lightpath.  How the lightpath is
> > routed in the
> > optical layer seems to me irrelevant to TE.
> 
> It's not up to you or me to say "irrelevant to TE"; the judge of
> relevancy is the user (SP), and it depends very much on how
> integrated the TE is between the optical domain and the routing
> domain.  I know several SPs that would like *in the long term* to
> have a tightly integrated TE between the two domains; of course
> the majority today prefer loose or no coupling, as that fits their
> current mode of operation.
> 
> From an analytical point of view, though, if you define TE as the
> mapping of flows to physical links, then it seems to me that how
> the lightpath is routed in the optical domain is very relevant.
> 
> Kireeti.

-- 
Zhi-Wei Lin
Lucent Technologies                       Tel: +1 732 949 5141
101 Crawfords Corner Rd, Rm 3C-512        Fax: +1 732 949 3210
Holmdel, New Jersey 07733-3030 USA      Email: zwlin@lucent.com