UCB Implementing QoS Jean Walrand EECS Outline UCB What Where End to End Edge to Edge Edge to End Overlay Mechanisms Bandwidth Delay Access Control Packet Marking Vegas Incentive Compatible Protocols DiffServ MPLS Pricing Flat Usage Congestion What UCB Throughput R Mbps Flow e g TCP connection Pipe e g IP source IP destination Possibly class e g VoIP Hose Aggregate rate out of port Timescale 1 Mbps over every ms 1 Mbps over every second What UCB continued Latency Upper bound T Dmax e g conference Dmax 200ms Jitter Tmax Tmin Jitter Playback buffer CBR What UCB continued Other Security e g VPN Measure of security Physical Fiber Link VLAN IP Ipsec Availability e g except for 1 hour every 10 years MTBF MTBR UCB Where Edge to edge Edge to edge End to end UCB Where continued Overlay Network QoS box edge to edge with QoS Mechanisms UCB Access Control Example MAN R 1 Gbps bi dir Police R to 1 Gbps N Guaranteed UCB Mechanisms Packet Marking continued Frank Kelly Mark with probability that the extra packet creates a loss User pays per mark and slows down when pay rate reaches budget Revenues Loss rate times unit cost Distributed according to willingness to pay By choosing unit cost adjust loss rate Throughput is then divided according to user utilities Single class but differentiated services UCB Mechanisms continued Vegas Window rate x Prop backlog Try to maintain a fixed backlog Equal backlogs Equal throughputs B Davie Extension to multiple bottleneck case J Mo Difficulty Not compatible with Reno Mechanisms UCB continued Incentive Compatible Protocols Problem If QoS is free users will ask for best As result wasted resources Solution Design protocols that discourage waste Attempt Voice Low delay larger loss Data Larger delay small loss E g differentiated RED with priority Shortcoming Can cheat with FEC for data Mechanisms UCB DiffServ Typically three classes continued Expedited Forwarding Low lagency e g VoIP Assured Forwarding Guaranteed rate Best Effort MPLS Typically long term SLAs Protection switching is possible Traffic Engineering to optimize network Mechanisms UCB continued Proposal Overlay Network Network domains implement AF or MPLS QoS Boxes implement Classification Policing Pricing QoS Transport e g Vegas Pricing UCB Flat Fee 30 00 month Usage Based 0 01 Mbyte Pro Encourages rational use Cons Unpredictable can learn risky can cap requires sophistication Congestion Based time of day spot price Pros Simple predictable bounded Cons Wasteful cannot provide 10Mbps on demand Pro Most rational leads to best utilization Cons Sophisticated requires software agents Mechanisms Heavy infrastructure necessary
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