Configuration Prerequisites; Configuring Igmp Message Options - HP 4800G Series Configuration Manual

Configuration Prerequisites

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:
Startup query interval
Startup query count
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

Configuring IGMP Message Options

IGMP queries include group-specific queries and group-and-source-specific queries, and multicast
groups change dynamically, so a device cannot maintain the information for all multicast sources and
groups, For this reason, 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 on whether it carries the Router-Alert option in
the IP header:
By default, for the consideration of compatibility, the device does not check the Router-Alert option,
namely it processes all the IGMP messages it received. In this case, IGMP messages are directly
passed to the upper layer protocol, no matter whether the IGMP messages carry the Router-Alert
option or not.
To enhance the device performance and avoid unnecessary costs, and also for the consideration
of protocol security, you can configure the device to discard IGMP messages that do not carry the
Router-Alert option.
Configuring IGMP packet options globally
Follow these steps to configure IGMP packet options globally:
To do...
Enter system view
Enter IGMP view
Configure the router to discard
any IGMP message that does
not carry the Router-Alert
option
Enable insertion of the
Router-Alert option into IGMP
messages
Use the command...
system-view
igmp
require-router-alert
send-router-alert
1-12
Remarks
—
—
Optional
By default, the device does not
check the Router-Alert option.
Optional
By default, IGMP messages
carry the Router-Alert option.