The MPLS WG Archive

[Francois Le Faucheur <flefauch@cisco.com>]

Curtis,

At 19:22 25/02/2000 -0500, Curtis Villamizar wrote:

>You have a fine I-D and I do agree that L-LSPs can be used if
>reservation per BA is desired.  It is just more efficient to use an
>E-LSP if more than one BA can be accomodated given the limited EXP
>bits and also given the requirements of the BAs wrt fast-reroute,
>adaptivity, and resilience match.  In the interest of making that
>improvement in efficience possible, I would prefer if you would add
>per BA (or per PHB as the MAPs are now defined) bandwidth as an option
>to the MAPs for E-LSPs.
>
>Please consider making this change to the I-D.
>

I am considering... but not convinced.

We agree that if one wants to do per-OA Routing and per-OA admission
Control, then this can be done using L-LSPs + bandwidth reservation as
currently defined. Call this Mode 1.
We also agree that if one  wants to do aggregate routing of Multiple-OAs
and Aggregate Admission Control of Multiple-OAs, then this can be done
using E-LSPs + bandwidth reservation as currently defined. CAll this Mode 2.

The suggestion above is for extensions allowing aggregate routing/transport
of multiple-OAs with per-OA admission control. Call this MOde 3. Firstly,
such an extension would also require defining the procedures and error code
for handling situations where the admission control for one OA is
successful while the admission control for another OA is rejected. You
woudl have to reject the E-LSP explaining which admission control failed.
Secondly, that would mean that you cannot route one OA onto a Path which
has capacity for it simply because it happens to travel on an E-LSP along
another OA which has run out of capacity. In other words, multi-OA Routing
with per-OA admission control achieves less efficient routing than Mode 2
would.
Is this not right?

So, all in all, I still think:
	- you can do pretty good and label-efficient with Mode 1 
	- you can do the ideal per-OA thing with Mode 2. 
	- Mode 3 does not have a strong application in between these 2.
	- there are already quite a lot of options in our spec...

Do you still see a strong application for Mode 3 which would justify
extensions in the MAP but also extensions in all the error codes and
procedures (today we rely on normal RSVP error handling to signal rejection
because of admission control)?

Opinions from others?

Cheers

Francois

>Thanks,
>
>Curtis
> 
_________________________________________________________________
Francois Le Faucheur   
Development Engineer, IOS Layer 3 Services 
Cisco Systems 
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