CH1' Introduction

1
CH1. Introduction

• Why multicasting?
• Outline and scope of the book
• Multicast tree
• Rate control, Scalability
• Sender-based rate control
• Receiver-driven rate control
• Hierarchy of agents combine two approaches
• Transport-layer services
• Total ordering
• Group membership

2
CH2. Multicasting Fundamentals

• Application of Multicast
• Interactive Streaming Reliable
• Ethernet Multicast
• Broadcast medium a little complicated for
  multicasting
• Broadcast address ffffffffffff
• IP multicast Class D address
• IP multicast using Ethernet broadcast / multicast
• 1st link layer broadcast, discarded at the IP
  layer
• 2nd a mapping of the IP multicast address to
  Ethernet multicast address
• 25 to 1 mapping problem
• IGMP
• Used between a host on a subnet and the
  corresponding router for the subnet
• A host informs the router that it want to join a
  particular IP multicast group
• Tree

3
CH 3. Multicast Routing Algorithms

• Shortest Path Tree algorithms
• Bellman-Ford, Dijkstra algorithms
• For each send-receiver pair -gt Minimize the
  end-to-end delay
• Minimum Cost Tree algorithm
• Minimize the overall cost of the tree
• Minimum Spanning Tree algorithm, Minimum Steiner
  Tree algorithm
• Constrained Tree algorithm
• Compute the minimum cost tree which does not have
  any path from the sender to a receiver that
  exceeds a delay bound
• Majority of the multicast routing protocols used
  in the Internet Today
• based on shortest path tree
• easy to implement
• provide minimum delay from the sender to each
  receiver

4
CH 4. IP Multicast

• Evolution of multicasting in the Internet
• Constructing the multicast tree at the IP layer
• Reverse Path Forwarding
• Source-based tree such that distance between S
  and any R is minimum
• Flood
• Only When interface that the router users to send
  packets to the sender
• Problems
• No notion of group membership, Broadcast tree
  (not multicast tree)
• Internet Group Management Protocol
• IGMP Host-Membership Query
• IGMP Host-Membership Report
• Source filtering version 3
• Deregister
• Do not need to explicitly inform soft state
• Explicitly inform version 2

5

• Truncated Broadcasting
• Reduce traffic in the leaf subnet
• pruning
• Distance Vector Multicast Routing Protocol
  (DVMRP)
• Refines truncated broadcast by using a mechanism
  called pruning
• Prune message is sent to its neighboring routers
• There is no group member on the subnet
• All interfaces except for the one on the reverse
  shortest path to S
• Soft-state protocol
• Graft message
• Cancels the prune state at the relevant routers

6
CH 5. MOSPF

• OSPF
• Link-State Protocol
• Complete picture of the topology of AS
  (Autonomous System)
• MOSPF
• Add Group membership-LSA
• Intra-area multicasting, Inter-area multicasting,
  Inter-AS multicasting
• Design Goals
• Extend OSPF to support multicasting
• Add minimal functionality to OSPF to support
  multicast

7

• Protocol Data Structures
• Local Group Database
• Local group DB group, subnet
• Create group-member-LSAs (Link State
  Advertisement)
• Forwarding Cache
• Upstream node, Downstream Interfaces
  (interfacehops)
• Multicasting routing capability
• Inter-area Multicast forwarder

8

• Protocol
• Joining a multicast group
• IGMP query
• IGMP response
• Create an entry in local group database
• Send group membership LSA
• Create an entry in local group databaseCreate a
  forwarding cache entry
• Leaving the multicasting group

9

• Data Forwarding
• Intra-area multicasting
• Link-state database
• Shortest path tree computation
• On demand
• Inter-area multicasting
• Group membership LSA
• Summary group membership LSA
• Multicast data forwarding
• Multicast forwarder routers - made into wild-card
  receivers
• Inter-area shortest path tree computation
• Based on Summary-link LSAs
• On demand
• Merging multiple shortest path tree
• Guarantee Inter-AS multicast