Igmp Queries; Igmp Reports - HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual

Configuring Multicast Support for a Stub Network
Overview
10-6
Group 99
Figure 10-4. Multicasting with IGMP

IGMP Queries

On the ProCurve Secure Router, you enable an interface to act as a multicast
agent when you do one of the following:
configure the interface as a multicast stub downstream interface
enable PIM-SM on the interface
The multicast agent broadcasts IGMP queries to all hosts, asking them to
generate a report for each host group to which they belong. The multicast
agent only forwards packets destined to a certain multicast address into the
networks from which it has received a report for that address.
The ProCurve Secure Router stores a list of the group memberships in
connected networks and a timer for each membership. When the membership
expires, the IGMP interface sends a new query.

IGMP Reports

When a host receives an IGMP query, it replies with IGMP reports. Each report
contains the multicast address of a group to which the host belongs. Hosts
minimize IGMP reports, which might otherwise flood the network, in
two ways:
Instead of immediately sending a report for every group to which it
belongs, the host staggers them. It sets a random timer for when it should
send each report.
Multicast
packet
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Multicast
packet
Router
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