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Bandwidth Constraints Models for DS-TE Where do we stand?

Bandwidth Constraints Models for DS-TE Where do we stand?. Francois Le Faucheur flefauch@cisco.com. Concensus on BC Model objectives. efficient use of bandwidth (ie good bandwidth sharing among CTs) Isolation across CTs (ie a CT cannot hogg the bw of another CT)

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Bandwidth Constraints Models for DS-TE Where do we stand?

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  1. Bandwidth Constraints Models for DS-TEWhere do we stand? Francois Le Faucheurflefauch@cisco.com

  2. Concensus on BC Model objectives • efficient use of bandwidth (ie good bandwidth sharing among CTs) • Isolation across CTs(ie a CT cannot hogg the bw of another CT) • protection against QoS degradation(at least of the premium CTs e.g Voice, Premium ...) • possible to operate without preemption(when preemption is disabled, still work "reasonably" well) • reasonably simple , no additional IGP extensions.

  3. Documented Models • Russian Dolls Model (RDM) • Maximum Allocation Model (MAM) • Maximum Allocation with Reservation (MAR)

  4. Concensus on RDM properties • Where preemption can be used, RDM works very well: • simultaneously achieves Bw efficiency, isolation and protection against QoS degradation • Where preemption can not be used, RDM works alright, but cannot achieve good isolation

  5. Concensus on MAM properties • MAM is "intuitive"/easy to conceptualise • Where preemption can not be used, MAM is attractive: • it is good at achieving isolation • if one doesn't worry too much about "QoS degradation" of lower/medium classes, then MAM can achieve bw efficiency and isolation

  6. A view on MAR(not Concensus view) • MAR works alright in some situations • (eg CT load on every link known a priori…) • But, in general, MAR: • cannot provide isolation and efficiency sumultaneously • See example on alias (link=100, RBW=10): • CT0 takes 90 • CT1 is only left with 10 • CT2 and CT3 are leaft with 0 • Cannot control CTs individually

  7. A Proposed Approach • Specify two models • RDM • MAM • Pick one Default, one Optional • Get some deployment experience and evaluate the need for another model

  8. Russian Dolls Model for DS-TEdraft-ietf-tewg-diff-te-russian-00.txt F Le Faucheur, T Nadeau : Cisco Systems Jim Boyle : PDNets K Kompella : Juniper Networks W Townsend : Tenor Networks D Skalecki : Nortel Networks

  9. Changes since proto-01 • Only change is to split from proto document

  10. Open issues • None

  11. Next Steps • Update diff-te-russian- to specify whether it is Default/Optional • Go for Last Call

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