1. UCB Multicasting Jean Walrand EECS

2. UCB Outline Definitions Broadcast, Multicast, Anycast Examples ARP, ICMP, Group Flooding Routing Multicast Tree of shortest paths; shortest tree Multicast Backbone Overlay Join Groups Soft State Reliable Multicast Nacks, Aggregation Multilayer Multicast

3. UCB Definitions Broadcast One to all Multicast One to all members of a group Anycast One to any member of a group

4. UCB Examples ARP: Broadcast to LAN (Note: VLANs) 11…11 = “broadcast” address on Ethernet ICMP: Routers broadcast their link states in OSPF Group: Multicast of seminar to “subscribers” Class-D IP addresses = group addresses

5. UCB Flooding Send on all other ports: Remember seen packets, or Mark route on packets BC A  [1]  {1} [1] BC A [1; A] [1; A, C][1; A, B]

6. UCB Routing Multicast Simplest: Tree of shortest paths Example 2 1 2 2 2 1 1 1 1 S D1 D2

7. UCB Routing Multicast (continued) Optimal: Shortest tree Example 2 1 2 2 2 1 1 1 1 S D1 D2

8. UCB Routing Multicast (continued) Comparison: 2 1 2 2 2 1 1 1 1 S D1 D2 2 1 2 2 2 1 1 1 1 S D1 D2 Tree of shortest paths Sum of lengths = 9 Shortest tree Sum of lengths = 8

9. UCB Routing Multicast (continued) RPB: Reverse Path Broadcast Router R sends packet received from A if A is on the shortest path from R to S. 2 1 2 2 2 1 1 1 1 S D1 D2 R Link AR A

10. UCB Routing Multicast (continued) RPM: Reverse Path Multicast RPB + Prune back if no member of Mcast group 2 1 2 2 2 1 1 1 1 S D1 D2 P R Link RP G Not G Prune

11. UCB Join G G Routing Multicast (continued) PIM-Dense Mode RPR + Prune + Graft (+ periodic RPR + Prune) 2 1 2 2 2 1 1 1 1 S D1 D2 Prune Graft

12. UCB Routing Multicast (continued) PIM-Sparse Mode Periodic Join/Prune Messages from DR to RP Assumption: Relatively few group members

13. UCB Reliable Multicast (continued) ACKs do not scale NACKs may implode => NACK aggregation 1 1 1 1 1 11

14. UCB Reliable Multicast (continued) ACKs do not scale NACKs may implode => NACK aggregation 2 2 22

15. UCB Reliable Multicast (continued) ACKs do not scale NACKs may implode => NACK aggregation 3 3 3 3 3 33 NACK2 [Remember for T seconds]

16. UCB Reliable Multicast (continued) Other idea: Designated Receivers NACK n [n] Source DR

17. UCB Multilayer Multicast Different channel bandwidths => Multiple Layers Source Layer 1 Layer 2 Random “join” experiments