RE: What we disagree on RE: TE Requirements Draft-ELSP

[Shai Herzog <sherzog@hyperchip.com>]

>-----Original Message-----
>From: owner-te-wg@ops.ietf.org [mailto:owner-te-wg@ops.ietf.org]On
>Behalf Of Sudhakar Ganti
>Sent: December 5, 2001 11:27 PM
>To: te-wg@ops.ietf.org
>Subject: RE: What we disagree on RE: TE Requirements Draft-ELSP
>
>
>Shai,
>
>If multiple BW signaling is a bad thing and yet
>we want a separation (or control) of BW between
>OAs of E-LSP, we can statically map the BW
>ratios of OAs in the whole network (say
>AF1/AF2=1/10 in your example) to solve the
>equation.

???

Are we in the DiffServ or the MPLS-TE WG?

Are we playing a game of "how many ways can we do BW encoding?"

What's the difference between signaling two BW numbers and signalling
one BW with a ratio split. It is only an encoding difference, but has
the same implementation/implications.

1. A fixed ratio around the network? How does that relate to
   End-to-End tunnel BW? (I hope you at least recognize that).

   Saying AF1 to AF2 is 1/10 in BW is no different than saying
   that all AF1 in the network get X BW, and AF2 get Y BW. Both
   have nothing to do with Traffic Engineering because the provide
   NO per tunnel QoS guarantees.

>The fun part is,

I not sure if find it funny hearing different "BW encoding" proposals 
that have no analysis of their implications. I wish we could take
a step backwards from the "What/how can we signal" but rather 
"What's the implications of a certain set of signalled constraints".

At some point one may ask him/her self what's the added benefits
vs. complexity. I will try to later today or tomorrow send out a 
more or less "methodical" analysis of implications of the different 
options of E-LSP and OAs. At least hoping to show the complexity side 
(not arguing the benefits side). 
 
The fun part would be arguing for/against it in the WG ;-)

Shai

>
>-Sudhakar
>> -----Original Message-----
>> From: owner-te-wg@ops.ietf.org [mailto:owner-te-wg@ops.ietf.org]On
>> Behalf Of Shai Herzog
>> Sent: Wednesday, December 05, 2001 4:05 PM
>> To: 'Siva Sivabalan'; 'te-wg@ops.ietf.org'
>> Subject: RE: What we disagree on RE: TE Requirements Draft-ELSP
>>
>>
>>
>>
>> >-----Original Message-----
>> >From: owner-te-wg@ops.ietf.org [mailto:owner-te-wg@ops.ietf.org]On
>> >Behalf Of Siva Sivabalan
>> >Francois,
>> >
>> >I totally agree with you ....
>> >
>> >My take is that we have to associate one and only one set 
>of signaled
>> >parameters with E-LSP, regardless of how many OAs it carries.
>>
>> I fully agree. Multiple BW and other parameters
>> is a BADDDDD thing.
>>
>> >When carrying
>> >multiple OAs, having different (per-OA) values for one set of
>> >parameters
>> >(e.g., bandwidth) and the same values for other set of
>> >parameters (e.g.,
>> >affinity) makes E-LSP complicated without strong incentives.
>>
>> Agree. But do you support multiple OAs with a single BW parameters?
>>
>> My point is that this doesn't make sense either because one can't
>> split the
>> BW between the different OAs.
>>
>> So, basically, if you use multiple OAs in an E-LSP, many 
>other parameters
>> (like BW, CSPF) become useless (and not permitted). This 
>means such E-LSPs
>> are only good for vanilla DiffServ (no signalled BW, no 
>constraint routes,
>> etc.). I'm not sure how usefull this could be for TE purposes.
>>
>> So, we're left with only the case of an E-LSP with a single OA as a
>> meaningfull TE approach. (which sounds awfully close if not 
>identical to
>> L-LSP).
>>
>> The fact that it is on someone's wish list doesn't cure the
>> problem at all.
>> It is computationally impossible to solve. (i.e., my example 
>of "How many
>> watermelons and cherries can you fit together into a given size box).
>>
>> If you disagree, please solve the following problem given only
>> the following
>> information:
>>
>> AF1+AF2=200Mb/s; how much BW is allocated to AF1?
>> (for admission control computation and queueing).
>>
>> Shai
>>
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