EE 122: Lecture 16/17 (Integrated Services)Integrated Services (Intserv)An Intserv Node ArchitectureData PlaneControl Plane: Resource Reservation Protocol (RSVP)RSVP Design FeaturesThe Big PictureSlide 8RSVP Basic OperationsRoute PinningPATH and RESV messagesReservation StyleReservation Styles and Filter SpecWildcard Filter ExampleSlide 15Wildcard FilterWildcard Filter: Inefficient Resource Utilization ExampleFixed Filter ExampleSlide 19Dynamic Filter ExampleTire-down ExampleSlide 22Soft StateRSVP and RoutingRecap of RSVPAdministrative StuffEE 122: Lecture 16/17(Integrated Services)Ion StoicaOctober 30/November 1, [email protected] 2Integrated Services (Intserv)Provide three services (see last lecture)-Best-effort (“elastic” applications)-Hard real-time (“real-time” applications)-Soft real-time (“tolerant” applications)[email protected] 3An Intserv Node Architecture Admission ControlData InData Out Control PlaneData PlaneSchedulerRouting Routing MessagesRSVP messagesClassifierRSVPRoute LookupForwarding TablePer Flow QoS [email protected] 4Data PlaneInput interface: -Lookup: use forwarding table to select the router’s output interface to forward the packetOutput 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 Queueing5Control Plane: Resource Reservation Protocol (RSVP)Signaling protocol for establishing per flow state required for-Admission control -Classification, buffer management, and schedulingCarry resource requests from hosts to routersCollect needed information from routers to hostsAt each hop-Consult admission control and policy module-Set up admission state or informs the requester of the [email protected] 6RSVP Design FeaturesIP Multicast centric designReceiver initiated reservationDifferent reservation stylesSoft state inside networkDecouple routing from reservation7The Big PictureNetworkSenderReceiverPATH Msg8The Big PictureNetworkSenderReceiverPATH MsgRESV [email protected] 9RSVP Basic OperationsTwo message types: PATH and RESVSender sends PATH message via the data delivery path-Set up the path state each router including the address of previous hopReceiver sends RESV message on the reverse path-Specify the reservation style, QoS desired-set up the reservation state at each routerThings to notice-Receiver initiated reservation-Decouple the routing from reservation-Two types of state: path and [email protected] 10Route PinningProblem: asymmetric routes-You may reserve resources on RS3S5S4S1S, but data travels on SS1S2S3R !Solution: use PATH to remember direct path from S to R, i.e., perform route pinning S1S1S2S2S3S3SSRRS5S5S4S4PATHRESVIP [email protected] 11PATH and RESV messagesPATH also specifies -Source traffic characteristics•Use token bucket-Reservation style – specify whether a RESV message will be forwarded to this serverRESV 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 [email protected] 12Reservation StyleMotivation: 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 reservationVarious reservation styles specify different rules for sharing among [email protected] 13Reservation Styles and Filter SpecReservation style-use filter to specify which sender can use the reservationThree 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 [email protected] 14Wildcard Filter ExampleReceivers: H1, H2; senders: H3, H4, H5Each sender sends BH1 reserves B; listen from one server at a timeS1S1S2S2S3S3H2H2H1H1H5H5H4H4H3H3(B,*)(B,*) (B,*)(B,*)(B,*)(B,*)[email protected] 15Wildcard Filter ExampleH2 reserves BS1S1S2S2S3S3H2H2H1H1H5H5H4H4H3H3(B,*)(B,*) (B,*)senderreceiver(B,*)(B,*) (B,*)(B,*)[email protected] 16Wildcard FilterAdvantages-Minimal state at routers•Routers need to maintain only routing state augmented by reserved bandwidth on outgoing linksDisadvantages -May result in inefficient resource [email protected] 17Wildcard Filter: Inefficient Resource Utilization ExampleH1 reserves 3B; wants to listen from all senders simultaneously Problem: reserve 3B on (S3:S2) although 2B sufficient ! S1S1S2S2S3S3H2H2H1H1H5H5H4H4H3H3(3B,*)(3B,*) (3B,*)[email protected] 18Fixed Filter ExampleReceivers: H2, H4, H5; Senders: H1, H3, H4, H5Routers maintain state for each receiver in the routing tableS1S1S2S2S3S3H2H2H1H1H3H3senderreceiverH5H4sender+receiverNextHop Sources H1 S2(H5, H4) H2 H1(H1), S2(H5, H4)[email protected] 19Fixed Filter ExampleH2 wants to receive B only from H4S1S1S2S2S3S3H2H2H1H1H3H3senderreceiverH5H4sender+receiver(B,H4)(B,H4)(B,H4)(B,H4)[email protected] 20Dynamic Filter ExampleH5 requests a reservation for two streams from any sourceS2 makes the reservation, forwards it to S1 and S3S1 only reserves bandwidth b toward H1S3 doesn’t do anythingS1S1S2S2S3S3H2H2H1H1H3H3senderreceiverH5H4sender+receiver(B,H4)(B,H4)(B,H4)(2B,*)(B,H4)(B,*)(B,*)[email protected] 21Tire-down Example H4 leaves the group-H4 no longer sends PATH message-State corresponding to H4 removedS1S1S2S2S3S3H2H2H1H1H3H3senderreceiverH5H4sender+receiver(B,H4)(B,H4)(B,H4)(2B,*)(B,H4)(B,*)(B,*)[email protected] 22Tire-down Example H4 leaves the group-H4 no longer sends PATH message-State corresponding to H4
View Full Document
Unlocking...