 SNU INC Lab Integrated Services RSVP Differentiated Services 전산과학과 정보통신 연구실 최 선 웅 9 월 23 일

 SNU INC Lab History  IP-based Internet provide a simple best-effort delivery service to all applications  New real-time, multimedia, and multicasting applications are not well supported, in IP-based Internet. construct a second networking infrastructure for real-time traffic replace the existing IP-based configuration with ATM

 SNU INC Lab Integrated Services Architecture(ISA)  Strong need to support a variety of traffic with a variety of QoS requirements, within the TCP/IP architecture  Fundamental requirement add new functionality to routers and a means for requesting QoS-based service from Internet  IETF is developing a suite of standards under the general umbrella of the Integrated Services Architecture(ISA)

 SNU INC Lab Integrated Services(intserv)  Integrated Services The transport of audio, video, real-time, and classical data traffic within a single network infrastructure  Purpose of this working group Define the enhanced Internet service model Defining the application service, router scheduling and (general) subnet interfaces Developing router validation requirements which can ensure that the proper service is provided  RFC’s Specification of the Controlled-Load Network Element Service (RFC 2211) Specification of Guaranteed Quality of Service (RFC 2212)

 SNU INC Lab Internet Traffic  Elastic Traffic can adjust to change in delay and throughput across Internet and still meet the needs of its applications non-real-time application FTP, SMTP, TELNET, SNMP, HTTP  Inelastic Traffic does not easily adapt to changes in delay and throughput across Internet real-time application

 SNU INC Lab Inelastic traffic  Inelastic traffic Tolerant / Intolerant  depending on whether they can tolerate occasional loss Adaptive / Non-adaptive  depending on their adaptability  Delay-adaptive / Rate-adaptive  Requirement for inelastic traffic need of means to give preferential treatment to applications with more demanding requirements elastic traffic must still be supported

 SNU INC Lab ISA Service Class  Guaranteed(RFC 2212) provide assured capacity level, or data rate specified upper bound on the queuing delay no queuing losses  Controlled load(RFC 2211) approximation no specified upper bound on the queuing delay, but ensure that a very high percentage of the packets do not experience delays that greatly exceed the minimum transit delay almost no queuing loss  Best effort

 SNU INC Lab Flow  Flow distinguishable stream of related IP packets that results from a single user activity and requires the same QoS  Flow vs. TCP connection A flow is unidirectional There can be more than one recipient of a flow(multicast)

 SNU INC Lab Internet Traffic Control  Conventional Traffic Control Routing algorithm  Most routing protocols in use in Internet allow routes to be selected to minimize delay Packet discard  When overflows, discard packets  Typically, the most recent packet is discarded  These tools have worked reasonably well

 SNU INC Lab Requirements  ISA Approach Flowspec Admission Control Routing algorithm  may be based on a variety of QoS parameters, not just minimum delay Queuing discipline Discard policy Resource reservation  Reservation Protocol(RSVP)

 SNU INC Lab IS Router Components  Classifier Incoming packet must be mapped into some class Choice of a class is based on fields in the packet header  Packet scheduler Manage queues for each output port Determine the order of packet transmission and discard Based on a packet’s class, the contents of the traffic control database, and current and past activity on this outgoing port Determine whether the packet traffic in given flow exceeds the required capacity and if so, decide how to treat the excess packets policing

 SNU INC Lab IS Router Components(Cont’d)  Admission Control Implement the decision algorithm Enforce administrative policy Accounting and administrative reporting  Reservation Setup Protocol Create and maintain flow-specific state Carry flowspec to admission control

 SNU INC Lab IS Host/Router Components

 SNU INC Lab Resource Reservation: RSVP  Design goals Heterogeneous receivers Dynamic multicast group membership Enable receivers to select one source from among multiple sources transmitting to a multicast group Deal gracefully with changes in routes, automatically reestablishing tree the resource reservation along the new paths Minimize protocol overhead Be independent of routing protocol  RFC’s Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification(RFC 2205)

 SNU INC Lab RSVP Characteristics  Characteristics Unicast and multicast Soft state Receiver-initiated reservation Simplex Different reservation styles Transparent operation through non-RSVP routers Support for IPv4 and IPv6

 SNU INC Lab Receiver-initiated Reservation  In ATM, the source of a data flow requests resources In unicast, this approach is reasonable Inadequate for multicasting  Why? Some members of a multicasting group may not require delivery from a particular source over some period of time Some members of a group may only be able to a portion of the source transmissions  Sender provide the routers with the traffic characteristics of the transmission  Receiver specify the desired QoS

 SNU INC Lab Soft State  Reservation state is cached information in the router  Periodically refreshed by end system  If a state is not refreshed within a required time limit, the router discards the state  If a new route becomes preferred for a given flow, the end systems provide the reservation to the new routers on the route

 SNU INC Lab RSVP Admission Control  RSVP process communicates with two local decision modules admission control  determines the node has sufficient available resources to supply the requested QoS policy control  determines whether the user has administrative permission to make the reservation

 SNU INC Lab RSVP Admission Control(Cont’d)  If either check fails, RSVP returns an error notification to the application process that originated the request  If both check succeed, RSVP sets parameters in a packet classifier and packet scheduler to obtain the desired QoS  The packet classifier determines the QoS class for each packet  The packet scheduler orders packet transmission to achieve the promised QoS for each stream

 SNU INC Lab RSVP Admission Policy(rap)

 SNU INC Lab Scalability  Scalability Receiver-oriented reservation requests that merge as they progress up the multicast tree  While RSVP protocol is designed specifically for multicast applications, it may also make unicast reservations

 SNU INC Lab Robustness  RSVP is designed to utilize the robustness of current Internet routing algorithms RSVP does not perform its own routing Use underlying routing protocols to determine where it should carry reservation requests As routing changes paths to adapt to topology changes, RSVP adapts its reservation to the new paths wherever reservations are in place  RSVP runs over IP, both IPv4 and IPv6

 SNU INC Lab Data Flows  Session Destination IP address IP protocol id Destination port  Flow spec Service class RSpec TSpec  Filter spec Source address UDP/TCP source port

 SNU INC Lab Relationship

 SNU INC Lab RSVP Operation: Filtering  An example of filtering Fig. Filtering a substream

 SNU INC Lab Reservation Styles  Reservation attribute shared/ distinct  Sender selection explicit/ wildcard

 SNU INC Lab Reservation Style Notation  Notation Filterspec{Flowspec}  Wildcard Filter(WF) style WF(*{Q})  Shared Explicit style SE(S1, S2, … {Q})  Fixed Filter(FF) style FF(S1{Q1}, S2{Q2}, …)

 SNU INC Lab

 SNU INC Lab Basic RSVP Message  Two basic message type Resv / Path  Path message Provide upstream routing information Each host that wishes to participate as a sender in a multicast group issues a Path message Transmitted throughout the distribution tree to all multicast destination  Resv message Originate at a receiver and propagate upstream, being merged Must be repeated periodically to maintain the soft states

 SNU INC Lab RSVP Mechanism Overview  Procedure a. A receiver joins a multicast group by sending an IGMP join message to a neighboring router b. A potential sender issues a Path message to the multicast group address c. A receiver receives a Path message identifying a sender d. The receiver sends Resv messages, specifying the desired flow descriptors e. The Resv message propagates through the internet and is delivered to the sender f. The sender starts sending data packets g. The receiver starts receiving data packets

 SNU INC Lab Reservation Example R1 S1 S2 R2N1N2 R3 Path(S1, S1)Path(N1, S1)Path(N2, S1) Path(N1, S2) Path(N2, S2)

 SNU INC Lab Reservation Example : WF R1 S1 S2 R2N1N2 R3 Resv(WF(*{5B}))Resv(WF(*{3B})) Resv(WF(*{2B})) Resv(WF(*{5B})) Resv(WF(*{5B})Resv(WF(*{5B}))

 SNU INC Lab Reservation Example : FF R1 R2N2 R3 Resv(FF(S1{4B}, S2{2B})) Resv(FF(S1{B}, S2{3B})) Resv(FF(S1{5B})) S1 S2 N1 Resv(FF(S1{5B}, S2{3B}))Resv(FF(S1{5B}))Resv(FF(S2{3B}))

 SNU INC Lab Reservation Example : SE R1 R2N2 R3 Resv(SE(S1, S2{2B})) Resv(SE(S1, S2{3B})) Resv(SE(S2{5B})) S1 S2 N1 Resv(SE(S1, S2{5B}))Resv(SE(S1{5B}))Resv(SE(S2{5B}))

 SNU INC Lab Flow Specification  Flowspec = Traffic Spec + QoS Spec = TSpec + RSpec  TSpec : Peak rate(p), bucket rate(r), bucket size(b), max datagram size(M), min policed unit(m) All datagrams less than m are counted as m bytes Peak rate may be unknown or unspecified  RSpec : Rate(R) and delay slack(S) S = Extra acceptable delay over that obtainable with R Zero slack ==> Reserve exactly R.  RSpec specified only for guaranteed rate service. Not for controlled load service.

 SNU INC Lab Guaranteed Service  Firm end-to-end delay bound  Error terms : C, D

 SNU INC Lab Path Message  Phop last node address  Sender Template Filter specification  Sender TSpec  Optional ADSPEC One Path With Advertising(OPWA) information

 SNU INC Lab Processing Path Message  Update the path state If no path state exists, create it  Store Phop In order to route Resv message  Set cleanup timer Expiration of the cleanup timer triggers deletion of the path state Soft-state

 SNU INC Lab ADSPEC  Optional object to advertise to receivers the characteristics of the end-to-end communication path  ADSPEC format Message header Default General Parameters fragment  minimum path latency, Global break bit, Path bandwidth, Integrated Service Hop Count, PathMTU Guaranteed Service fragment  C tot, D tot, C sum, D sum, Guaranteed Service Break bit, Guaranteed Service General Parameters Header/Values Controlled-Load Service fragment  Controlled-Load Service Break Bit, Controlled-Load Service General Parameters Headers/Values

 SNU INC Lab Reservation using OPWA  Q delreq : the required bound on end-to-end queuing delay End-to-end delay required by the receiver’s application – the minimum path latency  Initial check (R = p) Choose an equation  Find R

 SNU INC Lab Slack Term  S : slack term End-to-end delay required by the application – End-to-end delay bound C tot i : the cumulative sum of the error terms, C for all the routers that are upstream of, and including, the current element i

 SNU INC Lab

 SNU INC Lab Problems of Intserv  Resource reservations for flow-based traffic High overheads of setting-up a reservation Difficult determination of required resources Overhead of authentication, authorization, and accounting per flow  Scalability problem

 SNU INC Lab Differentiated Services (diffserv)  Objective Provide scalable service discrimination in the Internet without the need for per-flow state and signaling at every hop Simple and coarse methods of providing differentiated classes of service for Internet traffic  How-to-do Setting bits in the TOS octet at network edges and administrative boundaries Using those bits to determine how packets are treated by the routers inside the network Conditioning the marked packets at network boundaries in accordance with the requirements of each service

 SNU INC Lab Related Proposals  Premium Service(V. Jacobson) Scheduling priority Strict admission control Virtual leases line  Assured Service(D. Clark) Drop priority A better best-effort  User-Share Differentiation(Z. Wang) User  Who are granted some bandwidth Share  How much bandwidth is allocated to a user

 SNU INC Lab Diffserv Working Group  Feb 98 Working group formed  Goals Standardize the 'DS byte’ Assign specific per-hop behaviors to the DS byte Define the framework of the differentiated services architecture Experiment with other per-hop behaviors that can be used to produce additional services

 SNU INC Lab Terminology  Behavior aggregate A collection of packets with the same code point crossing a boundary in a particular direction  DS byte IPv4 TOS octet or IPv6 Traffic Class octet  Per-hop Behavior(PHB) Forwarding treatment applied at a differentiated services- enabled node to a behavior aggregate

 SNU INC Lab DS byte  PHB: per-hop behavior  CU: currently unused PHBCU

 SNU INC Lab Per-Hop Behaviors  Differentiated services model Router has a set of parameters that can be used to control how packets are scheduled onto an output interface N separate queues with settable priorities, queue lengths, round-robin weights, drop algorithm, drop preference weights and thresholds, etc  Two per-hop behaviors Default(DE: )  common, best-effort forwarding Expedited Forwarding(EF: )  high priority behavior typically used for network control traffic such as routing updates

 SNU INC Lab Traffic Classification and Conditioning  Packet classification Identify the subset of traffic which may receive a differentiated service within the DS domain  Traffic conditioning Metering, shaping, policing and remarking

 SNU INC Lab Classifier and Conditioner ClassifierMarker Meter Shaper/ Dropper Packets Conditioner

 SNU INC Lab Traffic Management  Traffic conditioner Meter  Measures traffic against profile  Passes state information to other conditioning functions Marker  Sets codepoint(possibly based on metering) Shaper/dropper  Delays or drops packets

 SNU INC Lab Summary  Support QoS in the Internet Intserv/RSVP Diffserv