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

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

GQS system arrangement guaranteed guaranteed (G) non-guaranteed (N) reservation signalling guaranteed Reservation enabled RSVP/ECN gateway ECN only Reserved flow processing Policing flow entry to G Meter congestion per peer Bulk ECN marking G prioritised over N IP routersData path processing table of ECN fraction per previous RSVP hop aggregate

b/w broker ECN legend connection- oriented (CO) connectionless gateways GQS GQS/core CO core CO/core CO access CO/core CO ECN MPLS RSVP-TE ECN various QoS signalling access networks PSTN heterogeneity assume app layer signalling (SIP) initiates out of band

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

data plane functions: virtual queue mgmt (VQM) CoS g CoS n qnqn line rate, X traffic class? G N 1 qnqn PnPn priority queuing drop (or ECN marking) probability qgqg 1 q g +q n PgPg ECN marking probability virtual output  ~ 99% XX vgvg CoS g virtual queue v g +q n

data plane functions: egress GQS traffic class? G N clear traffic class G clear ECN-capable transport lookup prev hop reserved flow table filterspec : prev RSVP hop maintain moving ave ECN fraction previous hop load prev RSVP hop : ECN fraction

Q wot, no inter-domain signalling gateway? Ano Qwot, no per session inter-domain charging? A no could by intercepting signalling, but not necessary, so if you did I’d hide it Qcan’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 Y X NANA NANA NBNB NBNB NDND NDND R1R1 S1S1 IP QoS transp QoS transp

summary 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

Guaranteed QoS Synthesiser (GQS) spare slides

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

inter-class load self-balancing Guaranteed Non-Guaranteed admission threshold TCP op. point #flows