Asante Technologies 35516 - Manual (Page 62)

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debug ip rip packet [recv | send] detail Display detailed information about the RIP packets. The
information includes the origin and port number of the packet
as well as a packet dump.
show debugging rip Show all information currently set for RIP debug.
5.5 Configuring IP Multicast Routing
Multicast traffic is a means to transmit a multimedia stream from the Internet (a video conference, for example)
without requiring a TCP connection from every remote host that wants to receive the stream.
Traditional IP communication allows a host to send packets to one host (unicast transmission) or to all hosts
(broadcast transmission). IP multicast provides a third scheme, allowing a host to send packets to a group of hosts
(group transmission). A multicast address is chosen for the members of a multicast group. Senders use that address
as the destination address of a datagram to reach all hosts of the group. The stream is sent to the multicast address,
and from there it’s delivered to all interested parties on the Internet. Any host, regardless of whether it is a member of
a group, can send to that group. However, only the members of the group receive the message.
The IC35516 supports the following protocols to implement IP multicast routing:
• Internet Group Management Protocol (IGMP): used between hosts on a LAN and the router(s) on that LAN to
track the multicast groups of which hosts are members
• Distance Vector Multicast Routing Protocol (DVMRP): used on the MBONE (the multicast backbone of the
Internet)
5.5.1 IGMP
The Internet Group Management Protocol (IGMP) manages the multicast groups on a LAN. IP hosts use IGMP to
report their group membership to directly connected multicast routers. Routers executing a multicast routing protocol
maintain forwarding tables to forward multicast datagrams. Routers use the IGMP to learn whether
members of a
group are present on their directly attached sub-nets. Hosts join multicast groups by sending IGMP report messages.
IGMP uses group addresses, which are Class D IP addresses. The high-order four bits of a Class D address are
1110. Therefore, host group addresses can be in the range 224.0.0.0 to 239.255.255.255.
The address 224.0.0.0 will not be assigned to any group. The address 224.0.0.1 is assigned to all systems on a sub-
net. The address 224.0.0.2 is assigned to all routers on a sub-net.
5.5.2 Configuring IGMP
Use the following commands to configure IGMP.
Modifying the IGMP Host-Query Message Interval
Multicast routers send IGMP host-query messages to discover which multicast groups are present on attached
networks. These messages are sent to the all-systems group address of 224.0.0.1 with a time-to-live (TTL) value
of 1.
Multicast routers continue to periodically send host-query messages to refresh their knowledge of memberships
present on their networks. If, after some number of queries, the router software discovers that no local hosts are
members of a multicast group, the software stops forwarding onto the local network multicast packets from remote
origins for that group and sends a prune message upstream toward the source.