(RSVP) Speaker: Dr. Whai-En Chen

Transcription

1 Resource ReSerVation Protocol (RSVP) Speaker: Dr. Whai-En Chen Assistant Professor Institute of Computer Science and Information Engineering National Ilan University (NIU) The source is obtained from Prof. Nen-Fu Huang. 1

2 Resource ReSerVation Protocol (RSVP) 國立清華大學資訊工程學系黃能富教授 Tel: Fax: URL: tw/~nfhuang All rights reserved. No part of this publication and file may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without prior written permission of Professor Nen-Fu Huang ( nfhuang@cs.nthu.edu.tw). 2

3 RSVP Documents RFC 2205 Resource ReSerVation Protocol (RSVP) -- Functional Specification RFC 2209 Resource ReSerVation Protocol (RSVP) -- Message Processing Rules RFC 2210 The Use of RSVP with IETF Integrated Services RFC 2211 Specification of Controlled-Load Network Element Service RFC 2212 Specification of Guaranteed Quality Service RFC 2215 General Characterization Parameter for Integrated Service Network Elements RFC 2216 Network Element Service Specification Template 3

4 Introduction of RSVP RSVP makes resource reservations for both unicast and multicast applications, adapting dynamically y to changing g group membership and routes. A resource reservation setup protocol designed for an integrated services Internet. Used by a host to request a specific QoS from the network. Also used by the routers to deliver QoS requests to all nodes along the path(s) of the data stream and to establish and maintain state to provide the requested service. 4

5 Introduction of RSVP RSVP reserve resources for simplex data streams (only one direction). Operates on top of IP (either IPv4 or IPv6), like ICMP, IGMP. Not a routing protocol, but designed to operate with current and future unicast and multicast routing protocol, like DVMRP (Distance Vector Multicast Routing Protocol), CBT (Core Based Tree), PIM (Protocol Independent Multicast), etc. An RSVP daemon consults the local routing database(s) to obtain routes. 5

6 Introduction of RSVP In the multicast case, a host sends IGMP messages to join a multicast group and then sends RSVP Resv messages to reserve resources along the delivery path(s) of that group. Incoming packets are passes through a packet classifier which determines the route and the QoS class for each packet. On outgoing g interface, a packet scheduler then makes forwarding decisions for every packet, to achieve the promised QoS on the particular linklayer medium. 6

7 Introduction of RSVP Admission control determines whether resources are sufficient to support the requested QoS. Policy control determines whether h the user is allowed to make the reservation. Uses soft state in the routers. RSVP sends periodic refresh messages to maintain the state along the reserved path(s); in absence of refreshes, the state will automatically time out and be deleted. 7

8 RSVP in Hosts and s Host RSVP RSVP AP RSVP daemon Policy Control Routing Protocol Daemon RSVP daemon Policy Control Data Classifier Packet Scheduler Admis Control Data Classifier Packet Scheduler Admis Control Data Packet Scheduler Data 8

9 RSVP Operation Example 2 Session (Ipa,PID,Port) 3 A path Session Manager 10 B IGMP 11 Receive (Ipa,PID,Port) 1 R 2 R Receive (Ipa,PID,Port) 13 Resv 6 path IGMP R 1 R 6 C DVMRP 14 7 path 8 Resv R 3 R 5 9 Resv path Resv 9

10 Data Flows RSVP defines a session to be a data flow with a particular destination and transport-layer protocol (TCP/UDP). The destination of a session is defined by DstAddr,, the IP destination address of the data packets. Protocol ID, DstPort, a generalized destination port (some further demultiplexing point in the transport or application protocol layer). 10

11 Reservation Model An elementary RSVP reservation request consists of a flow descriptor = (flowspec, filter spec). The flowspec defines a desired QoS and is used to set parameters in the node s packet scheduler. The filter spec defines the set of data packets (flow) to receive the QoS defined by the flow spec, and is used to set parameters in the node s packet classifier. 11

12 Reservation Model The flow spec includes a service class and two sets of numeric parameters: an Rspec (R for reserve) that defines the QoS, and a Tspec (T for Traffic) that describes the data flow. The filter specs may select arbitrary subsets of the packets in a given session. The one used in present RSVP consisting of sender IP addr and optionally the UDP/TCP port number SrcPort. 12

13 Reservation Styles A reservation request includes a set of options that are collectively called the reservation style. One concerns the treatment of reservations for different senders within the same session : establish a distinct reservation for each upstream sender, or else make a single reservation that is shared among all packets of selected senders. Another controls the selection of senders; an explicit list of all selected senders, or a wildcard that implicity selects all the senders to the session. 13

14 Reservation Styles Fixed-Filter (FF) Style Shared-Explicit (SE) Style Wildcard-Filter (WF) Style Sender Reservation Selection Distinct Shared Explicit Wildcard Fixed-Filter (FF) Style (None defined) Shared-Explicit (SE) Style Wildcard-Filter (WF) Style 14

15 Reservation Styles Wildcard-Filter d (WF) Style Shared reservation and wildcard sender selection. Creates a single reservation shared by all upstream senders. WF ( *{Q} ) Fixed-Filer (FF) Style Distinct reservation and explicit sender selection. Creates a distinct reservation for data packets from a particular sender. FF ( S {Q} ) <= a flow descriptor FF ( S1 {Q1}, S2 {Q2},... ) : The total reservation is the sum of Q1, Q2,... 15

16 Reservation Styles Shared Explicit (SE) Style Shared reservation and explicit sender selection. Creates a single reservation shared by selected upstream senders. SE ( {S1,S2,...}, {Q} ) 16

17 Reservation Styles These styles are all mutually incompatible. Shared reservations, created by WF and SE styles, are appropriate for those multicast applications in which multiple data sources are unlikely to transmit simultaneously (packetized audio). Distinct reservation (FF style) is appropriate for the flows from different senders (video signals). 17

18 Example of Styles S1 a c R1 S2,S3 b d LAN R2 R3 (a) Configuration WF (*{4B} }) S1 S2,S3 WF (*{4B} ) *{4B} *{3B} WF (*{4B} }) R1 WF (*{3B} }) LAN WF (*{2B} ) (b) WF Reservation Example R2 R3 18

19 Example of Styles FF (S1{4B} ) FF (S1{4B},S2{5B} ) S1{4B} S1 R1 S2{5B} S1{3B} FF (S1{3B},S3{B} S3{B} ) S2,S3 S3{B} LAN FF (S1{B} ) FF (S2{5B},S3{B} ) ()FFR (c) Reservation Example R2 R3 S1 SE (S1{3B} ) (S1,S2) {B} SE ((S1,S2){B} ) SE( (S1,S3){3B} S3){3B} ) (S1,S2,S3) S2,S3 {3B} SE (S2{2B} ) SE ((S2,S3){3B} ) (d) SE Reservation Example R1 LAN R2 R3 19

20 Example of Styles S1 a c S2,S3 b d R1 (a) Configuration LAN R2 R3 WF (*{4B} ) S1 *{4B} (*{3B} S2,S3S3 WF ) *{3B} WF (*{4B} ) WF (*{3B} ) WF (*{2B} ) R1 LAN R2 R3 (b) WF Reservation Example -Partial Routing 20

21 RSVP Protocol Mechanisms Previous Hops Incoming Interfaces data path A a c Resv data B path LAN b d B Resv Outgoing Interfaces data Resv path data Resv path LAN Next Hops C D D There are two fundamental RSVP message types: Resv and Path Each receiver host sends Rsev messages upstream towards the senders. These messages follow exactly the reverse of the path(s) the data packets will use, to all the selected senders. Each node along the path(s) creates and maintains i the reservation state. t 21

22 RSVP Protocol Mechanisms Each RSVP sender issues Path messages downstream along the uni-multicast routes provided by the routing protocol(s), following the paths of the data. Each node along the path(s) stores the path state (includes at least the IP address of the previous hop node). An RSVP session is normally defined by the triple: (Dest IP Address, Protocol ID, DstPort) TCP = 6, UDP = 17 22

23 Path Message Format <Path Message> ::= <Common Header> [<Integrity>] <Session> <RSVP_Hop> <Time_Values> [<Policy_Data>... ] [<Sender Descriptor>] <Sender Descriptor> ::= <Sender_Template> <Sender_Tspec> [<ADspec>] 23

24 Common Header Format Vers Flags Msg Type RSVP Checksum Send_TTL (Reserved) RSVP Length Message Type 1:Path 2 : Resv 3 : PathErr 4 : ResvErr 5 : PathTear 6 : ResvTear 7 : ResvConf 24

25 Object Formats Length (bytes) Class-Num C-Type (Object contents) 25

26 Class-Num NULL SESSION : (DestAddress, protocol ID, port) RSVP_HOP : The IP address of the RSVP-capable node that sent this message and logical outgoing interface handle (LIH). TIME_VALUES : Refresh period R. STYLE : Reservation style plus style-specific information. FLOWSPEC : Defines a desired QoS, in a Resv message. FILTER_SPEC : Defines a subset of session data packets that should receive the desired d QoS, in a Resv message. 26

27 Class-Num ADSPEC : Carries OPWA (one path with advertising) data, in a path message. ERROR_SPEC : Specifies an error in a PathErr, ResvErr, or a confirmation in a ResvConf message. POLICY_DATA : Carriers information for a local policy module to decide the permission of a reservation. INTEGRITY : Carriers cryptographic data to authenticate the originating g node and to verify the contents of the RSVP message. SCOPE : Carriers an explicit list of sender hosts. RESV_CONFIRM : Carriers the IP address of a receiver that requested a confirmation. 27

28 Path Message RSVP_Hop: IP address of previous RSVP node Sender Template : Describes the format of the data packets that the sender will originate. Sender Tspec Defines the traffic characteristics of the data flow that the sender will generate. Used by traffic control to prevent over-reservation. r : Token Bucket Rate (32-bit IEEE Floating Point number) b : Token Bucket Size (32-bit IEEE Floating Point number) p : Peak Data Rate (32-bit IEEE Floating Point number) m : Minimum i Policed Unit (32-bit integer) M : Maximum Packet Size (32-bit integer) 28

29 Sender Traffic Specific Sender r p > r data b M < b p M x <= (rt+b) min[pt, rt+b] b : Maximum burst size min[pt+m, rt+b] (packetize version) 29

30 Resv Message <Resv Message> ::= <Common Header> [<Integrity>] <Session> <RSVP_Hop> <Time_Values> [<Resv_Confirm>] [ <Scope>] [<Policy_Data>...] [<Style> <flow descriptor list>] <flow descriptor list> ::= <empty> <flow descriptor list> <flow descriptor> 30

31 Host Model Before a session can be created, the session ID must be assigned and communicated to all the senders and receivers by some out-of-band mechanism. When an RSVP session is being set up, the following events happen at the end systems: 31

32 Host Model A receiver joins the multicast group specified by DstAddr (Multicast), using IGMP. A potential sender starts sending RSVP Path messages to the DstAddr. A receiver application receives a Path message. A A receiver starts t sending appropriate Resv messages, specifying the desired flow descriptors. A sender application receives a Resv message. A sender starts sending data packets. 32

33 RSVP Attributes RSVP makes reservations for both unicast and multicast applications, adapting dynamically changing of group membership and routes. RSVP is simplex, it makes reservations for unidirectional data flows. RSVP is receiver-oriented. The receiver of a data flow initiates and maintains the resource reservation used for that flow. RSVP maintains soft state in the routers, providing graceful support for dynamic membership changes and automatic ti adaptation ti to routing changes. 33

34 RSVP Attributes RSVP is not a routing protocol but depends upon present and future routing protocols. RSVP transports and maintains opaque state for traffic control and policy control. RSVP provides several reservation models to fit a variety of applications. RSVP provides transparent operation through routers that do not support it. RSVP supports both IPv4 and IPv6. 34