The MPLS WG Archive

[Jim Boyle <jboyle@Level3.com>]

if the lambda's are unprotected (which is debatable), then the routers can
communicate amongst themselves and decide what are the failure scenarios,
and request more or less capacity based on that analysis.  

A complex alternative is to support things like:

a) "setup these two circuits in a diverse manner"
b) same as (a) but over different UNIs, in fact in different towns
(e.g. setup nyc-sfo diverse from wdc-lax)
c) "setup this circuit diverse from SRLG A,B,C" (which may be infeasible
if the circuit which those SRLGs were derived from preclude a diverse
route).

As for path selection in general, a knowledge of the underlying topology
is probably necessary for most optimal path selection when establishing
lightpaths for non-direct traffic.

This only makes sense in the 2001 timeframe to support one's ISP over
one's optical network.  An argument can be made that a good OSS makes a
lot of this level of integration unnecessary.  Inter-company is a whole
other issue.

regards,

Jim




On Mon, 23 Oct 2000, Sid Chaudhuri 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.  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.
> 
> Sid Chaudhuri
> 
> 
> 		-----Original Message-----
> 		From:	Kireeti Kompella [mailto:kireeti@juniper.net]
> 		Sent:	Monday, October 23, 2000 11:43 AM
> 		To:	xuyg@lucent.com; yxue@UU.NET
> 		Cc:	ip-optical@lists.bell-labs.com; mpls@UU.NET
> 		Subject:	Re: [IP-Optical] RE: Optical link bundling.
> Was Re: DraftMinutes From         Pittsburgh
> 
> 		Hi,
> 
> 		> > (router determines the explicit routes). 
> 		> 
> 		> This point has been raised by several folks. It really
> confuses me. If the
> 		> optical switches are equipped with path calculation
> ability, what's the benefit
> 		> to bother router to determine the explicit routes within
> optical domain
> 		> (assuming router can be smart enough to handle all optical
> network specific
> 		> attributes and constrains) than just have routers to
> determine the end points of
> 		> optical trails.
> 
> 		Why does this confuse you?  Routers may want to determine
> the exact
> 		path that their LSPs take for a number of reasons, including
> TE and
> 		protection.  If a router doesn't care where its LSPs are
> laid out,
> 		it can install loose hops at the boundaries of the optical
> cloud.
> 
> 		Kireeti.
>