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Guaranteed QoS Synthesiser (GQS)

Guaranteed QoS Synthesiser (GQS). Bob Briscoe, Peter Hovell BT Research Jan 2005. GQS goals (realised). v cheap Internet-wide statistical guarantees for inter-domain μ flows cores rarely congest but if/when they do you’re screwed uses existing protocols, but not their architectures

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Guaranteed QoS Synthesiser (GQS)

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  1. Guaranteed QoS Synthesiser(GQS) Bob Briscoe, Peter Hovell BT Research Jan 2005

  2. GQS goals (realised) • v cheap Internet-wide statistical guarantees for inter-domain μflows • cores rarely congest but if/when they do you’re screwed • uses existing protocols, but not their architectures • RSVP (other signalling possible), DSCP, ECN • not Intserv, not Diffserv, not e2e ECN • neither path signalling nor state… • …on core AND border routers • incremental deployment • scales better as more networks join • no-one has to trust anyone else • incentives against inter-provider cheating

  3. 1 2 3 3 3 3 4 1 IP routers Data path processing Reservationenabled GQS system arrangement Reserved flow processing 1 Policing flow entry to G 2 table of ECN fraction per previousRSVP hop aggregate RSVP/ECNgateway Meter congestion per peer 4 ECN only Bulk ECN markingG prioritised over N 3 reservation signalling guaranteed guaranteed guaranteed (G) guaranteed non-guaranteed(N)

  4. legend connection-oriented (CO) connectionless gateways GQS GQS/core CO core CO/core CO access CO/core CO variousQoS signallingaccess networks heterogeneity b/w broker PSTN MPLSRSVP-TE ECN ECN ECN ECN ECN assume app layer signalling (SIP) initiates out of band ECN

  5. reserved flow table filterspec : flowspec 1 2 3 3 3 3 4 1 data plane functions: ingress GQS explanation easier if we start by assuming we have already admitted a flow set traffic class G and set ECN-capable transport Y filterspec matches reservation and passes policer packetarrives N re-mark any spoof G to BE

  6. virtualqueue vg+qn X virtualoutput  ~ 99% CoSg vg 1 2 3 3 3 3 4 1 ECN markingprobability data plane functions:virtual queue mgmt(VQM) Pg 1 qg+qn G priorityqueuing trafficclass? CoSn CoSg line rate,X qn qg N Pn 1 qn drop (or ECN marking)probability

  7. previous hop load prev RSVP hop : ECN fraction reserved flow table filterspec : prev RSVP hop 1 2 3 3 3 3 4 1 data plane functions: egress GQS maintain moving ave ECN fraction clear traffic class Gclear ECN-capable transport lookupprev hop G trafficclass? N

  8. transp transp QoS QoS QoS QoS IP IP IP IP IP IP IP IP 1 2 3 3 3 3 NB 4 1 NA R1 ND S1 Q wot, no inter-domain signalling gateway? Y A no  Q wot, no per session inter-domain charging? A no  could by intercepting signalling, but not necessary, so if you did I’d hide it  Q can’t X admit calls despite congestion in Y? A emulate inter-domain policing monthly charge for bulk ECN counter at each border dead simple to meter & account X

  9. it works it’s simple it’s cheap it’s robust it’s secure it’s deployable what else do you want? status two implementations (2000-4) FreeBSD & Linux extensive simulation full design documentation looking for vendor take-up summary

  10. Guaranteed QoS Synthesiser(GQS) spare slides

  11. no time for… • probing when no active flows between gateway pair • robustness during re-routes • ECN mechanisms for incentives • ingress setting of ECT(0) & ECT(1) • VBR • preventing starvation • policy-based admission control

  12. inter-class load self-balancing Guaranteed admissionthreshold Non-Guaranteed TCPop. point #flows

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