McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Chapter 14 Multicasting And Multicast Routing Protocols

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 CONTENTS INTRODUCTION MULTICAST ROUTING MULTICAST TREES MULTICAST ROUTING PROTOCOLS DVMRP MOSPF CBT PIM MBONE

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 INTRODUCTION 14.1

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure 14-1 Unicasting

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 In unicast routing, the router forwards the received packet through only one of its interfaces.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure 14-2 Multicasting

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 In multicast routing, the router may forward the received packet through several of its interfaces.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure 14-3:a Multicasting versus multiple unicasting

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure 14-3:b Multicasting versus multiple unicasting

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Emulation of multicasting through multiple unicasting is not efficient and may create long delays, particularly with a large group.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 MULTICAST ROUTING 14.2

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 MULTICAST TREES 14.3

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 In a source-based tree approach, the combination of source and group determines the tree.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 In the group-shared tree approach, the group determines the tree.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 MULTICAST ROUTING PROTOCOLS 14.4

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure 14-4 Multicast routing protocols

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 DVMRP 14.5

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure 14-5 Reverse path forwarding

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 In reverse path forwarding (RPF), the router forwards only the packets that have traveled the shortest path from the source to the router; all other copies are discarded.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 RPF prevents the formation of loops.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure 14-6 Reverse path broadcasting

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure 14-7 RPF versus RPB

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 RPB creates a shortest path broadcast tree from the source to each destination. It guarantees that each destination receives one and only one copy of the packet.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure 14-8 RPF, RPB, and RPM

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 RPM adds pruning and grafting to RPB to create a multicast shortest path tree that supports dynamic membership changes.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 MOSPF 14.6

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure 14-9 Unicast tree and multicast tree

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 CBT 14.7

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure Shared-group tree with rendezvous router

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure Sending a multicast packet to the rendezvous router

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 In CBT, the source sends the multicast packet (encapsulated in a unicast packet) to the core router. The core router decapsulates the packet and forwards it to all interested hosts.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 PIM 14.8

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 PIM-DM is used in a dense multicast environment, such as a LAN environment.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 PIM-DM uses RPF and pruning/grafting strategies to handle multicasting. However, it is independent from the underlying unicast protocol.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 PIM-SM is used in a sparse multicast environment such as a WAN.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 PIM-SM is similar to CBT but uses a simpler procedure.

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 MBONE 14.9

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure Logical tunneling

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Figure MBONE

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 DVMRP supports MBONE