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5 Multicast

Multicast features on switches

1. IGMP Snooping 1.1 Enabling IGMP Snooping Normally, a switch should forward multicast frames out all ports. It will forward the traffic to all receivers, but it will also forward it to many hosts that don’t need it. To optimize this behavior, Cisco routers implement IGMP Snooping. With IGMP Snooping, …

IPv6 Multicast

1. IPv6 Multicast Addressing FF00::/8 Multicast addresses represent a group of interfaces, just like in IPv4 multicast. The format of a multicast address is: Flags: The R Flag is used for addresses with an embedded RP. The P Flag indicates a multicast address that is assigned based on the network …

Inter Domain Multicast

1. MSDP (Multicast Source Discovery Protocol) PIM-DM is not a viable solution to use over Internet, so we will use PIM-SM for interdomain multicast routing. PIM-SM Requires a Randezvous Point. In PIM-SM, when a source starts to transmit, the DR on it’s segment will register the source with the RP.Then, …

IGMP 101

To make multicast work, we use 2 types of protocols: one that is used to signal the receivers to the routers, and the other used by the routers to build distribution trees from the source to the receivers. In the first category we have IGMP (Internet Group Management Protocol), while …

PIM 101

1. PIM basics PIM is a protocol used to create loop-free multicast delivery trees from the source to the receivers. There are 2 different modes for PIM – Dense Mode and Sparse Mode, and a few other variations: PIM Sparse-Dense Mode, Bidirectional PIM and Source Specific PIM. PIM uses the …

Multicast 101

1. Multicast Addressing 1.1 Layer 3 Addressing Multicast IP packets are sent from the source to a destination IP in the range 224.0.0.0/4 (224.0.0.0 – 239.255.255.255). It means every multicast IP address starts with 1110 bits. This range is further subdivided in several blocks. The most important ones are: Local …