The MPLS WG Archive

["Daniel N. Bauer" <dnb@zurich.ibm.com>]

Shahram, Marcus,

What about the following thought:

For an E-LSP, the aggregate bandwidth is known. This aggregate bandwidth
corresponds to the sum of bandwidths that are requested for each PHB class
that are carried inside the E-LSP. In case that the distribution of the
PHB classes is known, then admission control could be carried out.
In networks where resources are pre-allocated per PHB class
and where this is done consistently on all LSR, then the distribution
of the pre-allocated resources can be used to carry out admission control
per E-LSP.

For example, consider the following distribution:
EF gets 5%, AF1.x gets 10%, AF2.x gets 20%, AF3.x gets 20%, AF4.x gets 20%;
meaning that on a 100Mbit/s link, EF could reserve up to 5 Mbit/s, AF1.x up
to 10Mbit/s, etc. etc.

If now an E-LSP requests 7 Mbit/s and this E-LSP carries EF, AF1.x and AF3.x
traffic, then the 7 Mbit/s could be split up and assigned to the classes
as follows:
EF - 1 Mbit/s
AF1.x - 2 Mbit/s
AF3.x - 4 Mbit/s
according to the 'weights' of the resource distribution.
Then, admission control for each class could be done seperately. The E-LSP
could be admitted if all of the admission control checks succeed.

Does this sound reasonable?

Of course, the whole scheme does not work if the pre-allocated resource distribution
is not consistent amont all LSR routers.

Best regards,

-Daniel



Marcus Brunner wrote:
> 
> Shahram,
> 
> In many scenarios, the admission control for a PBH scheduling classes is
> already fuzzy, which means on a statistical level, you will run into
> trouble if you want to do admission control for aggregates of different
> PHB classes.
> 
> Marcus
> 
> Shahram Davari wrote:
> >
> > Hi Daniel,
> >
> > You can do admission control for E-LSP too. But the admission control is done for the aggregate of all supported PHBs in that LSP.
> >
> > Regards,
> > -Shahram