Multicast Dan lI CS Department, Tsinghua University 2021/2/11
Multicast 2021/2/11 1 Dan LI CS Department, Tsinghua University
Today's Lecture Why Multicast? iP multicast service models Host-Router Signaling: IGMP Multicast Distribution Trees and Forwarding Multicast Routing protocols Reliable multicast ulticast Overlay Reading List 2021/2/11
Today’s Lecture Why Multicast? IP multicast service models Host-Router Signaling: IGMP Multicast Distribution Trees and Forwarding Multicast Routing Protocols Reliable multicast Multicast Overlay Reading List 2021/2/11 3
Multicast Routing Unicast: one source to one destination w Multicast: one source to many destinations Main goal: efficient data distribution Avoid data duplication within network 2021/2/11 4
Multicast Routing Unicast: one source to one destination Multicast: one source to many destinations Main goal: efficient data distribution Avoid data duplication within network 2021/2/11 4
Multicast- Efficient Data Distribution Src Src ↓↓| 2021
Multicast – Efficient Data Distribution 2021/2/11 5 Src Src
EXample Applications Broadcast audio/video Push-based systems(e. g. BGP updates Software distribution Web-cache updates Teleconferencing (audio, video, shared whiteboard, text editor) Multi-player games Other distributed applications 2021/2/11
Example Applications Broadcast audio/video Push-based systems (e.g., BGP updates) Software distribution Web-cache updates Teleconferencing (audio, video, shared whiteboard, text editor) Multi-player games Other distributed applications 2021/2/11 6
Multicast Advantages Enhanced Efficiency: Co and reduces serverand ctpplsoaetwork trattic Optimized performance: Eliminates traffic redundancy Distributed Applications: Makes multipoint applications possible Example: Audio Streaming □ Multicast All clients listening to the same 8 Kbps audio 口 Unicast 0.8 0.6 Traffic Mbps 0.4 0.2 20 40 60 80 100 20 40 60 80 100 2021/2/11 f clients
Multicast Advantages Enhanced Efficiency: Controls network traffic and reduces server and CPU loads Optimized Performance: Eliminates traffic redundancy Distributed Applications: Makes multipoint applications possible 2021/2/11 7 1 20 40 60 80 100 Example: Audio Streaming All clients listening to the same 8 Kbps audio 0 0.2 0.4 0.6 0.8 Traffic Mbps 1 20 40 60 80 100 # Clients Multicast Unicast
Multicast Disadvantages Multicast is udP based!!! Best Effort Delivery k Drops are to be expected No Congestion Avoidance Lack of TCP windowing and"slow-start mechanisms can result in network congestion Duplicates Out of Order Delivery 2021/2/11
Multicast Disadvantages Multicast Is UDP Based!!! Best Effort Delivery: Drops are to be expected No Congestion Avoidance: Lack of TCP windowing and “slow-start” mechanisms can result in network congestion Duplicates Out of Order Delivery 2021/2/11 8
Today's Lecture Why Multicast? IP multicast service models Host-Router Signaling: IGMP Multicast Distribution Trees and Forwarding Multicast Routing protocols Reliable multicast ulticast Overlay Reading List 2021/2/11
Today’s Lecture Why Multicast? IP multicast service models Host-Router Signaling: IGMP Multicast Distribution Trees and Forwarding Multicast Routing Protocols Reliable multicast Multicast Overlay Reading List 2021/2/11 9
IP Multicast Architecture Service model Hosts Host-to-router protocol (IGMP) Routers Multicast routing protocols varIous 2021/2/11
IP Multicast Architecture 2021/2/11 10 Hosts Routers Service model Host-to-router protocol (IGMP) Multicast routing protocols (various)
IP Multicast service Model Each group identified by a single IP address Variable size. k groups of any size sparse or dense Variable location mem bers may be located anywhere on Internet Dynamic membership Members can join and leave at will 2021/2/11 11
IP Multicast Service Model Each group identified by a single IP address Variable Size: Groups of any size; sparse or dense Variable Location: Members may be located anywhere on Internet Dynamic membership: Members can join and leave at will 2021/2/11 11