Adjusting Igmp Performance - 3Com Switch 4800G 24-Port Configuration Manual

620 C 46: IGMP C
HAPTER
Configuring a Multicast
Group Filter
Adjusting IGMP
Performance
Configuration
Prerequisites
Configuring IGMP
Message Options
ONFIGURATION
n
Before you can configure an interface of a PIM-SM device as a static member
■
of a multicast group, if the interface is PIM-SM enabled, it must be a PIM-SM
DR; if this interface is IGMP enabled but not PIM-SM enabled, it must be an
IGMP querier.
As a static member of a multicast group, an interface does not respond to the
■
queries from the IGMP querier, nor does it send an unsolicited IGMP
membership report or an IGMP leave group message when it joins or leaves a
multicast group. In other words, the interface will not become a real member
of the multicast group.
You can configure a multicast group filter in IGMP Snooping. For details, see
"Configuring a Multicast Group Filter" on page 566.
n
For the configuration tasks described in this section
Configurations performed in IGMP view are effective on all interfaces, while
■
configurations performed in interface view are effective on the current
interface only.
If the same feature is configured in both IGMP view and interface view, the
■
configuration performed in interface view is given priority, regardless of the
configuration sequence.
Before adjusting IGMP performance, complete the following tasks:
Configure any unicast routing protocol so that all devices in the domain are
■
interoperable at the network layer.
Configure basic functions of IGMP
■
Before adjusting IGMP performance, prepare the following data:
IGMP general query interval
■
IGMP querier's robustness variable
■
Maximum response time for IGMP general queries
■
IGMP last-member query interval
■
Other querier present interval
■
As IGMPv2 and IGMPv3 involve group-specific and group-and-source-specific
queries, and multicast groups change dynamically, a device cannot join all
multicast groups. Therefore, when receiving a multicast packet but unable to
locate the outgoing interface for the destination multicast group, an IGMP router
needs to leverage the Router-Alert option to pass the multicast packet to the
upper-layer protocol for processing. For details about the Router-Alert option, refer
to RFC 2113.
An IGMP message is processed differently depending whether it carries the
Router-Alert option in the IP header: