5.7 Multicast

How does Multicast differ from Unicast and Broadcast?

1. Multicast: Creates logical froups of hosts messages sent to the group are recievd by all group members. Multicast is typically used for streaming video and audio applications, such as video conferencin. 2. Unicasting: Messages are sent to a specific host address. the sending device must know the IP address of all recipients, and must create a seperate packet for each destination device. 3. Broadcasting: A single packet is sent to the broadcast address and is processed by all hosts. All hosts and not just group members, recieve the packet. Broadcast packets are not typically forwarded by routers, so broadcast traffic is limired to w/in a single subnet.

What does a regular switch do when it recieves a multicat frame?

A regular switch that recieves multicast traffic out all ports, b/c the destination MAC address will be an unknown address. this means that a host might see multicast traffic on its segment, even if it isn't a member of the group. However, hosts that are not members of the group will not process the frame b/c they will not associate the multicast MAC address with their own address.

What is the IP address range reserved for multicast groups?

Host that are members of any groups respond with a list of the they belong to. Each group is identified w/ a multicast IP address in the range of 224.0.0.0 to 239.255.255.255.

Which device would you configure to prevent multicast traffic from being sent to non-group members?

IGMP snooping on a switch allows the switch to control which ports get IGMP traffic for a specific group. With IGMP snooping the switch identifies which ports include members of a specific multicast group. When a message is revieved for a group, the message is sent only to the ports that have a group member connected.