Multicast Router Responsibilities Learn of the existence of multicast groups through advertisement Identify links with group members Establish state to route packets k Replicate packets on appropriate interfaces Routing entry Src, incoming interface List of outgoing interfaces 2021/2/11
Multicast Router Responsibilities Learn of the existence of multicast groups through advertisement Identify links with group members Establish state to route packets Replicate packets on appropriate interfaces Routing entry: 2021/2/11 17 Src, incoming interface List of outgoing interfaces
Today's Lecture Why Multicast? iP multicast service models Host-Router Signaling: IGMP Multicast Distribution Trees and Forwarding Multicast Routing protocols Reliable multicast ulticast Overlay Reading List 2021/2/11
Today’s Lecture Why Multicast? IP multicast service models Host-Router Signaling: IGMP Multicast Distribution Trees and Forwarding Multicast Routing Protocols Reliable multicast Multicast Overlay Reading List 2021/2/11 18
Getting Packets to End Hosts We havent treated general methods for this yet but the problem is having both a unicast and multicast P Packets from remote sources will only be forwarded by ip routers onto a local network only if they know there is at least one ecipient for that group on that network 2021/2/11
Getting Packets to End Hosts We haven’t treated general methods for this yet but the problem is having both a unicast and multicast IP Packets from remote sources will only be forwarded by IP routers onto a local network only if they know there is at least one recipient for that group on that network 2021/2/11 19
Getting Packets to End Hosts(Cont) Internet Group Management Protocol(IGMP, RFC2236) Used by end hosts to signal that they want to join a specific multicast group k Used by routers to discover what groups have interested member hosts on each network to which they are attached Implemented directly over IP 2021/2/11
Getting Packets to End Hosts (Cont.) Internet Group Management Protocol (IGMP, RFC2236) Used by end hosts to signal that they want to join a specific multicast group Used by routers to discover what groups have interested member hosts on each network to which they are attached Implemented directly over IP 2021/2/11 20
IGMP- Joining a group IGMP Membership-Report Example: R joins to Group 224.2.0.1 R R sends igmP Mem bership- Report Network a to224.2.0.1 dr receives it dr will start forwarding packets for 224.2.0.1 DR to Network a Network b DR periodically sends IGMP Membership-Query to 224.0.0.1 (ALL-SYSTEMS MCAST.NET R: Receiver DR: Designated router R answers igmP Membership- Report to 224.2.0.1 2021/2/11
IGMP – Joining a group Example : R joins to Group 224.2.0.1 R sends IGMP MembershipReport to 224.2.0.1 DR receives it. DR will start forwarding packets for 224.2.0.1 to Network A DR periodically sends IGMP Membership-Query to 224.0.0.1 (ALL-SYSTEMS.MCAST.NET) R answers IGMP MembershipReport to 224.2.0.1 2021/2/11 21 R R: Receiver DR: Designated Router IGMP Membership-Report Network A Network B DR