R3303-HP HSR6800 Routers IP Multicast Configuration Guide

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Configuring Router-Alert option handling methods

IGMP queries include group-specific queries and group-and-source-specific queries. Multicast groups

change dynamically, so a device cannot maintain the information for all multicast sources and groups.

For this reason, when an IGMP router receives a multicast packet but cannot locate the outgoing interface

for the destination multicast group, it must use the Router-Alert option to pass the multicast packet to the

upper-layer protocol for processing. For more information about the Router-Alert option, see RFC 2113 .

An IGMP message is processed differently depending on whether it carries the Router-Alert option in the

IP header:

• For compatibility, the device by default ignores the Router-Alert option and processes all received

IGMP messages, no matter whether the IGMP messages carry the Router-Alert option.

• To enhance device performance, avoid unnecessary costs, and ensure protocol security, configure

the device to discard IGMP messages that do not carry the Router-Alert option.

Configuring Router-Alert option handling methods globally

Ste

Command Remarks

1. Enter system view.

system-view N/A

2. Enter public network IGMP

view or VPN instance IGMP

view.

igmp [ vpn-instance

vpn-instance-name ]

N/A

3. Configure the router to

discard any IGMP message

that does not carry the

Router-Alert option.

require-router-alert

By default, the device does not

check the Router-Alert option.

4. Enable insertion of the

Router-Alert option into IGMP

messages.

send-router-alert

By default, IGMP messages carry

the Router-Alert option.

Configuring Router-Alert option handling methods on an interface

Ste

Command Remarks

1. Enter system view.

system-view N/A

2. Enter interface view.

interface interface-type

interface-number

N/A

3. Configure the interface to