Paradyne BitStorm 2400, User Manual

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1. BitStorm 2400 Overview
2400-A2-GB20-10 December 2002
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IGMP Protocols
IGMP v2 is backward compatible with IGMP v1. IGMP Version 2 extended the
IGMP Version 1 standard by adding support for an explicit group leave message
and a group specific query message. These new messages greatly improve the
efficiency of stopping the multicast flows once a subscriber no longer has interest
in the group (has shut down or changed the channel).
Most modern IP Multicast applications, routers, and end stations will support
IGMP V2 per RFC 2236. Support for the IGMP V1 messages and operation mode
is required by the IGMP standard for backward compatibility. IGMP v3 is still a draft
at this time and will be considered for future implementation.
IGMP protocol support requires the following operations:
!
Join Group
!
Membership Query
!
Membership Report
!
Leave Group
Join Group
When a host GigE joins a multicast group, it transmits an unsolicited Membership
Report for that multicast group.
Membership Query
Membership Queries are sent by IP multicast routers to learn which multicast
groups have members on its neighboring interfaces. Two types of query are
defined:
!
General Query – sent by a multicast router and received by all hosts with
membership in a multicast group.
!
Group-Specific Query (IGMP V2 only) – sent by a multicast router and
received by only those hosts that belong to the specific multicast group.
Membership Report
Membership Reports are generated and sent by hosts in response to Membership
Query messages that they have received. Membership Reports can also be
generated unsolicited as in the case of a Join Group operation.
In response to a General Query, end stations will generate report messages for
each group in which they are interested in participating. IGMP V2 hosts will
receive and respond to Group-Specific Query messages only if they are in the
specified group.