Using IP Multicast

- What is IP Multicast ?

Traditionally, IP packets are transmitted in two ways - unicast or broadcast. Multicast is a third way to deliver IP packets to a group of hosts. Host groups are identified by class D IP addresses, i.e., those with "1110" as their higher-order bits. In dotted decimal notation, host group addresses range from 224.0.0.0 to 239.255.255.255. Among them, 224.0.0.1 is assigned to the permanent IP hosts group, and 224.0.0.2 is assigned to the multicast routers group.

IGMP (Internet Group Management Protocol) is the protocol used to support multicast groups. The latest version is version 2 (see RFC2236). IP hosts use IGMP to report their multicast group membership to any immediate-neighbor multicast routers so the multicast routers can decide if a multicast packet needs to be forwarded. At start up, the Prestige queries all directly connected networks to gather group membership.

After that, the Prestige updates the information by periodic queries. The Prestige implementation of IGMP is also compatible with version 1. The multicast setting can be turned on or off on Ethernet and remote nodes.

- IP Multicast Setup

Enable IGMP in Prestige's LAN in menu 3.2:

Menu 3.2 - TCP/IP and DHCP Setup DHCP Setup DHCP= Server Client IP Pool Starting Address= 192.168.1.33 Size of Client IP Pool= 32 Primary DNS Server= 0.0.0.0 Secondary DNS Server= 0.0.0.0 Remote DHCP Server= N/A TCP/IP Setup: IP Address= 192.168.1.1 IP Subnet Mask= 255.255.255.0 RIP Direction= Both Version= RIP-1 Multicast= IGMP-v2 IP Policies= Edit IP Alias= No Press ENTER to Confirm or ESC to Cancel:

Enable IGMP in Prestige's remote node in menu 11.3:

`Menu 11.3 - Remote Node Network Layer Options` `IP Options: Bridge Options:` `Rem IP Addr: Ethernet Addr Timeout(min)= N/A` `Rem Subnet Mask= 0.0.0.0` `My WAN Addr= 0.0.0.0` `NAT = None` `Address Mapping Set= N/A Metric= 2` `Private= No` `RIP Direction= Both` `Version= RIP-2B` `Multicast= IGMP-v2` `IP Policies=` `Enter here to CONFIRM or ESC to CANCEL:`

Key Settings:

Multicast | IGMP-v1 for IGMP version 1, IGMP-v2 for IGMP version 2.

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