复旦大学：《计算机网络 Computer Networking》课程电子教案（PPT课件讲稿）11 Multicast

Computer Networking ecture 11-Multicast

Computer Networking Lecture 11 – Multicast

Multicast Routing Unicast: one source to one destination Multicast: one source to many destinations Main goal: efficient data distribution Lecture11:10-3-2006

Lecture 11: 10-3-2006 2 Multicast Routing • Unicast: one source to one destination • Multicast: one source to many destinations • Main goal: efficient data distribution

Overview IP Multicast Service Basics Host/router Interaction · MOSPF/DVMRP Overlay Multicast Lecture11:10-3-2006 3

Lecture 11: 10-3-2006 3 Overview • IP Multicast Service Basics • Host/Router Interaction • MOSPF/DVMRP • Overlay Multicast

Multicast- Efficient data distribution Src Src ↓↓| ↓↓|4↓ Lecture11:10-3-2006

Lecture 11: 10-3-2006 4 Multicast – Efficient Data Distribution Src Src

EXample Applications Broadcast audio/video Push-based systems Software distribution Web-cache updates Teleconferencing(audio, video, shared whiteboard, text editor) Multi-player games Server/service location Other distributed applications Lecture11:10-3-2006 5

Lecture 11: 10-3-2006 5 Example Applications • Broadcast audio/video • Push-based systems • Software distribution • Web-cache updates • Teleconferencing (audio, video, shared whiteboard, text editor) • Multi-player games • Server/service location • Other distributed applications

P Multicast architecture Service model Hosts Host-to-router protocol (IGMP Routers Multicast routing protocols (various) Lecture11:10-3-2006

Lecture 11: 10-3-2006 6 IP Multicast Architecture Hosts Routers Service model Host-to-router protocol (IGMP) Multicast routing protocols (various)

Logical Naming Single name/address maps to logically related set of destinations Destination set multicast group Key challenge: scalability Single name/address independent of group growth or changes Lecture11:10-3-2006

Lecture 11: 10-3-2006 7 Logical Naming • Single name/address maps to logically related set of destinations • Destination set = multicast group • Key challenge: scalability • Single name/address independent of group growth or changes

Multicast Router responsibilities Learn of the existence of multicast groups (through advertisement) Identify links with group members Establish state to route packets Replicate packets on appropriate interfaces Routing entry Src, incoming interface List of outgoing interfaces Lecture11:10-3-2006

Lecture 11: 10-3-2006 8 Multicast Router Responsibilities • Learn of the existence of multicast groups (through advertisement) • Identify links with group members • Establish state to route packets • Replicate packets on appropriate interfaces • Routing entry: Src, incoming interface List of outgoing interfaces

P Multicast Service Model (rfc1112) Each group identified by a single IP address Groups may be of any size Members of groups may be located anywhere in the Internet Members of groups can join and leave at will Senders need not be members Group membership not known explicitly Analogy. Each multicast address is like a radio frequency, on which anyone can transmit, and to which anyone can tune-in Lecture11:10-3-2006

Lecture 11: 10-3-2006 9 IP Multicast Service Model (rfc1112) • Each group identified by a single IP address • Groups may be of any size • Members of groups may be located anywhere in the Internet • Members of groups can join and leave at will • Senders need not be members • Group membership not known explicitly • Analogy: • Each multicast address is like a radio frequency, on which anyone can transmit, and to which anyone can tune-in

P Multicast Addresses Class d IP addresses 224.0.0.0-239255.255.255 1110 Group ID How to allocated these addresses? Well-known multicast addresses assigned by lanA Transient multicast addresses assigned and reclaimed dynamically, e.g., by sdr program Lecture11:10-3-2006

Lecture 11: 10-3-2006 10 IP Multicast Addresses • Class D IP addresses • 224.0.0.0 – 239.255.255.255 • How to allocated these addresses? • Well-known multicast addresses, assigned by IANA • Transient multicast addresses, assigned and reclaimed dynamically, e.g., by “sdr” program 1 1 1 0 Group ID