Multicast - Nortel BSR222 Configuration

Chapter 6 LAN screens 95
Both RIP-2B and RIP-2M send routing data in RIP-2 format; the difference
being that RIP-2B uses subnet broadcasting while RIP-2M uses multicasting.
Multicasting can reduce the load on nonrouter machines since they generally do
not listen to the RIP multicast address and so do not receive the RIP packets.
However, if one router uses multicasting, then all routers on your network must
use multicasting, also.
By default, RIP Direction is set to Both and RIP Version to RIP-1.

Multicast

Traditionally, IP packets are transmitted in one of two ways—Unicast (1 sender-1
recipient) or Broadcast (1 sender-everybody on the network). Multicast delivers
IP packets to a group of hosts on the network—not everybody and not just 1.
IGMP (Internet Group Multicast Protocol) is a network layer protocol used to
establish membership in a Multicast group—it is not used to carry user data.
IGMP version 2 (RFC 2236) is an improvement over version 1 (RFC 1112) but
IGMP version 1 is still in wide use. If you want to read more detailed information
about interoperability between IGMP version 2 and version 1, see sections 4 and 5
of Internet Group Management Protocol (RFC 2236). The class D IP address is
used to identify host groups and can be in the range 224.0.0.0 to 239.255.255.255.
The address 224.0.0.0 is not assigned to any group and is used by IP multicast
computers. The address 224.0.0.1 is used for query messages and is assigned to
the permanent group of all IP hosts (including gateways). All hosts must join the
224.0.0.1 group in order to participate in IGMP. The address 224.0.0.2 is assigned
to the multicast routers group.
The Business Secure Router supports both IGMP version 1 (IGMP-v1) and
IGMP version 2 (IGMP-v2). At start up, the Business Secure Router queries all
directly connected networks to gather group membership. After that, the Business
Secure Router periodically updates this information. IP multicasting can be
enabled or disabled on the Business Secure Router LAN, WAN or both interfaces
in the WebGUI (LAN; WAN). Select None to disable IP multicasting on these
interfaces.
Nortel Business Secure Router 222 Configuration — Basics