Re: Is the advertisement (IGP) of available BW at each pre-emption le vel is a DS-TE- requirement ?

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

Choudhury,

At 20:17 09/11/2001 -0500, Jim Boyle wrote:

> On Fri, 9 Nov 2001, Choudhury, Sanjaya
> wrote:

>       Q3. In a DiffServ TE domain, where the network administrator
>       initiates the creation the TE tunnels (using MPLS-TE-MIB ),
>       when/how can he take advantage of the following pre-emption
>       scheme:
>               a) Preemption within the same DiffServ traffic class
>               b) Preemption across different DiffServ traffic classes

I'm not sure how people use the MPLS-TE-MIB to setup TE tunnels, so I
can't help you there.  I think you mean class-type above, so again, that
is a specific proposal.

I am not sure I fully get the question (in particular I don't see the
relationship with the fact that you set up tunnels using MIB or not), but
let me quote some draft text from teh drafts we're working on as it may
help:

"
First, a Service Provider using two Class-Types (one for Voice and one
for Data), may elect to configure the following to ensure that Voice LSPs
are never driven away from their shortest path because of Data 
LSPs:

        -

all
Voice LSPs to preemption priority 0

        -

all
Data LSPs to preemption priority 1

Another Service Provider may elect to configure the following in order to
optimize global network resource utilization by favoring placement of
large LSPs first:

-       

all
large size Voice LSPs to preemption priority 0

-       

all
large size Data LSPs to preemption priority 1

-       

all
small size Voice LSPs to preemption priority 2

-       

all
small size Data LSPs to preemption priority 3
"

Note that this is based on the observation that, today, a common use for
preemption is to give higher preemption to large LSPs in order to get
better global utilisation. You get a much better network utilisation by
fitting big things first and then small ones (just like filling up the
boot of the family car when going away on holidays, really).


Hope that helps.

Francois

>
>       Thanks,
>       sanjay
>
>

_________________________________________________________

Francois Le Faucheur  

Development Engineer, IOS Layer 3 Services

Cisco Systems

Office Phone:          +33 4 97 23 26 19

Mobile :               +33 6 89 108 159

Fax:                   +33 4 97 23 26 26

Email:                 flefauch@cisco.com

_________________________________________________________

Cisco Systems

Domaine Green Side

400, Avenue de Roumanille

06 410  Biot - Sophia Antipolis

FRANCE

_________________________________________________________