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1 ©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl , 2003 1 Chapter 14 Multicasting And Multicast Routing Protocols INTRODUCTION MULTICAST ROUTING MULTICAST TREES MULTICAST ROUTING PROTOCOLS DVMRP MOSPF CBT PIM MBONE

Multicasting And Multicast Routing Protocols

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Chapter 14. Multicasting And Multicast Routing Protocols. INTRODUCTION MULTICAST ROUTING MULTICAST TREES MULTICAST ROUTING PROTOCOLS DVMRP MOSPF CBT PIM MBONE. Figure 14-1. 14.1 Introduction: Unicasting. In unicast routing, the router forwards - PowerPoint PPT Presentation

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Page 1: Multicasting And Multicast Routing Protocols

1©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 200311

Chapter 14

Multicasting And MulticastRouting Protocols

INTRODUCTION MULTICAST ROUTING MULTICAST TREES MULTICAST ROUTING PROTOCOLS DVMRP MOSPF CBT PIM MBONE

Page 2: Multicasting And Multicast Routing Protocols

2©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 200322

Figure 14-1

In unicast routing, the router forwards

the received packet through

only one of its interfaces.

14.1 Introduction: Unicasting

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3©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 200333

Figure 14-2

Multicasting

In multicast routing, the router may forward the

received packet through several of its interfaces.

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4©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 200344

Figure 14-3

Multicasting versus multiple unicasting

Emulation of multicasting through multiple unicasting is not

efficient and may create long delays,

particularly with a large group.

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5©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 200355

Application of Multicasting

Access to Distributed Databases Information Dissemination: e.g. multicast software updates to

customers News Delivery Teleconferencing, Web Seminars Distant Learning

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6©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 200366

14.3 Multicast Routing

Objectives Every member receives EXACTLY ONE copy of the packet Non-members receive nothing No loops in route Optimal path from source to each destination.

Terminology Spanning Tree: Source is the root, group members are the leaves. Shortest Path Spanning Tree: Each path from root to a leaf is the

shortest according to some metric

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7©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 200377

14.3 Multicast Trees

Source-Based Tree: For each combination of (source , group), there is a shortest path

spanning tree. Approach 1: DVMRP; an extension of unicast distance vector

routing (e.g. RIP) Approach 2: MOSPF; an extension of unicast link state routing

(e.g. OSPF) Group-Share Tree

One tree for the entire group Rendezvous-Point Tree: one router is the center of the group and

therefore the root of the tree. CBT and PIM-SP protocols.

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8©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 200388

Figure 14-4

14.4 Multicast routing protocols

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9©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 200399

14.5 Distance Vector Multicast Routing Protocol - DVMRP

No pre-defined route from source to destination. Tree is gradually created by successive routers along the path.

Uses shortest path (fewest hops) Prevent loops: apply Reverse Path Forwarding (RFP) Prevent Duplication: apply Reverse Path Broadcasting (RPB) Multicast with dynamic membership: apply Reverse Path

Multicasting (RPM) with pruning, grafting, and lifetime.

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10©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 20031010

Figure 14-5

Reverse Path ForwardingIn 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. No Loops

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11©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 20031111

Figure 14-6

Reverse Path BroadcastingPrevent Duplication in RPF

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12©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 20031212

Figure 14-7

RPF versus RPB

The router with the shortest path to the source becomes the designated parent of a network

A Router forwards packets only to its designated child networks

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13©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 20031313

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.

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14©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 20031414

Figure 14-8

RPF, RPB, and RPM

RPM adds pruning and grafting to RPB to create a multicast shortest

path tree that supports dynamic membership changes.

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15©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 20031515

MOSPF

14.614.6

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16©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 20031616

Figure 14-9

Unicast tree and multicast tree

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17©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 20031717

Core-Based TreeCBT

14.714.7

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18©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 20031818

Figure 14-10

Shared-group tree with rendezvous router

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19©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 20031919

Figure 14-11Sending a multicast packet to

the rendezvous router

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20©The McGraw-Hill Companies, Inc., 2000 © Adapted for use at JMU by Mohamed Aboutabl, 20032020

In CBT, the source sends the In CBT, the source sends the multicast packet (encapsulated in a multicast packet (encapsulated in a unicast packet) to the core router. unicast packet) to the core router. The core router decapsulates the The core router decapsulates the

packet and forwards it packet and forwards it to all interested hosts. to all interested hosts.