EE 122 Lecture 16 17 Integrated Services Ion Stoica October 30 November 1 2001 Integrated Services Intserv Provide three services see last lecture Best effort elastic applications Hard real time real time applications Soft real time tolerant applications istoica cs berkeley edu 2 Routing RSVP Admission Control Forwarding Table Data In Route Lookup Per Flow QoS Table Classifier istoica cs berkeley edu Scheduler RSVP messages Data Plane Routing Messages Control Plane An Intserv Node Architecture Data Out 3 Data Plane Input interface Lookup use forwarding table to select the router s output interface to forward the packet Output interface Classification classify each packet to the flow it belongs to A flow identified by source and destination IP addresses source and destination port numbers protocol type Buffer management Scheduling schedule each packet such that each flow achieves the promised service E g Weighted Fair Queueing istoica cs berkeley edu 4 Control Plane Resource Reservation Protocol RSVP Signaling protocol for establishing per flow state required for Admission control Classification buffer management and scheduling Carry resource requests from hosts to routers Collect needed information from routers to hosts At each hop Consult admission control and policy module Set up admission state or informs the requester of the failure 5 RSVP Design Features IP Multicast centric design Receiver initiated reservation Different reservation styles Soft state inside network Decouple routing from reservation istoica cs berkeley edu 6 The Big Picture Network Sender PATH Msg Receiver 7 The Big Picture Network Sender PATH Msg Receiver RESV Msg 8 RSVP Basic Operations Two message types PATH and RESV Sender sends PATH message via the data delivery path Set up the path state each router including the address of previous hop Receiver sends RESV message on the reverse path Specify the reservation style QoS desired set up the reservation state at each router Things to notice Receiver initiated reservation Decouple the routing from reservation Two types of state path and reservation istoica cs berkeley edu 9 Route Pinning Problem asymmetric routes You may reserve resources on R S3 S5 S4 S1 S but data travels on S S1 S2 S3 R Solution use PATH to remember direct path from S to R i e perform route pinning S2 S2 R R S S S1 S1 S3 S3 IP routing PATH RESV S4 S4 istoica cs berkeley edu S5 S5 10 PATH and RESV messages PATH also specifies Source traffic characteristics Use token bucket Reservation style specify whether a RESV message will be forwarded to this server RESV specifies Queueing delay and bandwidth requirements Source traffic characteristics from PATH Filter specification i e what senders can use reservation Based on these routers perform reservation istoica cs berkeley edu 11 Reservation Style Motivation achieve more efficient resource utilization in multicast M x N Observation in a video conferencing when there are M senders only a few can be active simultaneously Multiple senders can share the same reservation Various reservation styles specify different rules for sharing among senders istoica cs berkeley edu 12 Reservation Styles and Filter Spec Reservation style use filter to specify which sender can use the reservation Three styles wildcard filter does not specify any sender all packets associated to a destination shares same resources Group in which there are a small number of simultaneously active senders fixed filter no sharing among senders sender explicitly identified for the reservation Sources cannot be modified over time dynamic filter resource shared by senders that are explicitly specified Sources can be modified over time istoica cs berkeley edu 13 Wildcard Filter Example Receivers H1 H2 senders H3 H4 H5 Each sender sends B H1 reserves B listen from one server at a time B H2 H2 S1 S1 H1 H1 B B S2 S2 B B H3 H3 S3 S3 B H4 H4 H5 H5 receiver sender istoica cs berkeley edu 14 Wildcard Filter Example H2 reserves B H2 H2 B S1 S1 H1 H1 B B B S2 S2 B B H3 H3 S3 S3 B H4 H4 H5 H5 receiver sender istoica cs berkeley edu 15 Wildcard Filter Advantages Minimal state at routers Routers need to maintain only routing state augmented by reserved bandwidth on outgoing links Disadvantages May result in inefficient resource utilization istoica cs berkeley edu 16 Wildcard Filter Inefficient Resource Utilization Example H1 reserves 3B wants to listen from all senders simultaneously Problem reserve 3B on S3 S2 although 2B sufficient H3 H3 H2 H2 S1 S1 H1 H1 3B 3B S2 S2 3B S3 S3 H4 H4 H5 H5 receiver sender istoica cs berkeley edu 17 Fixed Filter Example Receivers H2 H4 H5 Senders H1 H3 H4 H5 Routers maintain state for each receiver in the routing table H2 H2 NextHop Sources H1 S2 H5 H4 H2 H1 H1 S2 H5 H4 S1 S1 S2 S2 H3 H3 S3 S3 H4 H1 H1 H5 receiver sender sender receiver istoica cs berkeley edu 18 Fixed Filter Example H2 wants to receive B only from H4 H2 H2 H3 H3 B H4 S1 S1 B H4 S2 S2 B H4 S3 S3 B H4 H1 H1 H4 H5 receiver sender sender receiver istoica cs berkeley edu 19 Dynamic Filter Example H5 requests a reservation for two streams from any source S2 makes the reservation forwards it to S1 and S3 S1 only reserves bandwidth b toward H1 S3 doesn t do anything H2 H2 B H4 S1 S1 H1 H1 H3 H3 B B H4 S2 S2 B H4 2B B S3 S3 B H4 H4 H5 receiver sender sender receiver istoica cs berkeley edu 20 Tire down Example H4 leaves the group H4 no longer sends PATH message State corresponding to H4 removed H2 H2 B H4 S1 S1 H1 H1 H3 H3 B B H4 S2 S2 B H4 2B B S3 S3 B H4 H4 H5 receiver sender sender receiver istoica cs berkeley edu 21 Tire down Example H4 leaves the group H4 no longer sends PATH message State corresponding to H4 removed H3 H3 H2 H2 S1 S1 H1 H1 B S2 S2 S3 S3 2B B H5 receiver sender sender receiver istoica cs berkeley edu 22 Soft State Per session state has a timer associated with it path state reservation state State lost when timer expires Sender Receiver periodically refreshes the state resends PATH RESV messages resets timer Claimed advantages no need to clean up dangling state after failure can tolerate lost signaling packets signaling message need not be reliably transmitted easy to adapt to route changes State can be explicitly deleted by a Teardown message istoica cs berkeley edu 23 RSVP and Routing RSVP designed to work with variety of routing protocols Minimal routing service RSVP asks routing how to route a PATH message Route pinning addresses QoS changes due to avoidable route changes while
View Full Document
Unlocking...