TCP/IP Protocol Suite 1 Multicasting and Multicast Routing Protocols Differentiate between a unicast and a multicast message Understand multicast link state routing and MOSPF Understand the Protocol Independent Multicast Protocols Objectives

TCP/IP Protocol Suite 2 UNICAST and MULTICAST A message can be unicast, multicast, or broadcast. Let us clarify these terms as they relate to the Internet. In unicasting, the router forwards the received packet through only one of its interfaces. In unicast communication, there is one source and one destination. The relationship between the source and destination is one-to-one.

TCP/IP Protocol Suite 3 Multicasting In multicasting, the router may forward the received packet through several of its interfaces. In multicast communication, there is one source and a group of destinations. The relationship is one-to-many. Multicasting has many applications today such as access to distributed databases, information dissemination, teleconferencing, and distance learning.

TCP/IP Protocol Suite 4 Multicasting versus multiple unicasting Emulation of multicasting through multiple unicasting is not efficient and may create long delays, particularly with a large group.

TCP/IP Protocol Suite 5 Shortest path tree in unicast routing In unicast routing, each router in the domain has a table that defines a shortest path tree to possible destinations.

TCP/IP Protocol Suite 6 Source-based tree approach There are two types of shortest path tree in multicast routing: source- based tree and group-shared tree. In the source-based tree approach, each router needs to have one shortest path tree for each group.

TCP/IP Protocol Suite 7 Group-shared tree approach In the group-shared tree approach, only the core router, which has a shortest path tree for each group, is involved in multicasting.

TCP/IP Protocol Suite 8 Taxonomy of common multicast protocols MOSPF: Multicast Open Shortest Path First DVMRP: Distance Vector Multicast Routing Protocol PIM: Protocol Independent Multicast PIM-DM: PIM, Dense Mode PIM-SM: PIM, Sparse Mode CBT: Core-Based Tree No multicast router available in today’s Internet

TCP/IP Protocol Suite 9 Multicasting Routing Protocols MOSPF is a multicast link state routing using source-based tree approach. DVMRP is a multicast distance vector routing. The Core-Based Tree (CBT) protocol is a group-shared protocol that uses a core as the root of the tree. The autonomous system is divided into regions and a core (center router or rendezvous router) is chosen for each region. PIM-DM is used in a dense multicast environment, such as a LAN. PIM-SM is used in a sparse multicast environment such as a WAN.

TCP/IP Protocol Suite 10 1.Intradomain and interdomain routing 2.Unicast routing: distance vector routing, link state, path vector routing 3.RIP, OSPF and BGP 4.RIP table update 5.Dijkstra’s shortest path algorithm to find the shortest path tree 6.Difference between multicast and unicast 7.Source-based multicast tree and group based multicast tree Summary

TCP/IP Protocol Suite A router running RIP has a routing table with 20 entries. How many periodic timers are needed to handle this table? How many expiration timers are needed to handle this table? Suppose 5 routes are invalid, how many garbage collection timer are needed to handle this table? 2. Below is a network, using Dijkstra algorithm to find the shortest path tree of the node A and E, and construct their routing table. Excises A H B C D E F G

TCP/IP Protocol Suite periodic timer is needed. 20 expiration timer are needed 5 garbage timer are needed, each for 1 invalid entry 2. Shortest path tree for A Solutions A H B C D E F G 5

TCP/IP Protocol Suite Routing table of A Solutions-cont. I NodeCostNext Router A0- B4- C5- D7B E9B F11B G12B H14B

TCP/IP Protocol Suite Shortest path tree of E Solutions-cont. II A H B C D E F G

TCP/IP Protocol Suite Routing table of A Solutions-cont. III NodeCostNext Router A9D B5D C6- D2- E0- F2- G4F H5F