H3C S7500E Series Ethernet Switches Operation Manual

Operation Manual – Multicast
H3C S7500E Series Ethernet Switches Chapter 4 IGMP Configuration
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4.4.1 Configuration Prerequisites
Before adjusting IGMP performance, complete the following tasks:
z Configure any unicast routing protocol so that all devices in the domain are
interoperable at the network layer.
z Configure basic functions of IGMP
Before adjusting IGMP performance, prepare the following data:
z IGMP general query interval
z IGMP querier’s robustness variable
z Maximum response time for IGMP general queries
z IGMP last-member query interval
z Other querier present interval
4.4.2 Configuring IGMP Message Options
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:
z 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.
z 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.
I. Configuring IGMP packet options globally
Follow these steps to configure IGMP packet options globally:
To do... Use the command... Remarks
Enter system view
system-view
—
Enter IGMP view
igmp
—
Configure the router to
discard any IGMP message
that does not carry the
Router-Alert option
require-router-alert
Optional
By default, the device
does not check the
Router-Alert option.