Hello,
Quickly
went through the thread we had on BC models before/during Yokohama.
My take
on it is that:
1) There is some
concensus on BC Model objectives:
-i- it
should be possible to disable preemption as
some network may not want to use preemption
-ii- when preemption
is disabled, the Model should still work "reasonably" well.
-iii- there
should be effective use of bandwidth (ie good bandwidth sharing among
CTs).
-iv- there
should be some isolation (ie a CT cannot hogg the bw of another
CT).
-v- there
should be protection against QoS degradation (at least of the
premium CTs e.g Voice, Premium Data...).
-vi- the BC model should be
reasoanly simple and shouldn't require additional IGP
extensions.
2) Maximum
Allocation Model (MAM) :
- MAM is "intuitive"/easy to conceptualise
- In environments where preemption is not to be used, MAM is
attractive because:
* it is good at
achieving isolation.
* if one doesn't worry too
much about "QoS degradation" of lower/medium classes, then MAM can achieve
reasonable bw efficiency.
- it cannot simultaneously achieve isolation, bw efficiency and
protection against QoS degradation
3) Russian Dolls
Model (RDM):
- In environments where preemption can be used, RDM is attractive
because it can simultaneously achieve Bw efficiency, isolation and protection
against QoS degradation (ie -iii-, -iv- and -v-)
- in environments where preemption is not to be used, RDM cannot achieve good
isolation.
4) Other
Models:
- Jerry indicated it is actually possible to achieve -iii-, -iv-, -v-
without preemption and will document another BC Model (maximum allocation with
reservation (MAR)) which achieves this.
Are we in
synch?
Cheers
Francois