102
•
Determine the startup query interval.
•
Determine the startup query count.
•
Determine the IGMP general query interval.
•
Determine the IGMP querier's robustness variable.
•
Determine the maximum response time for IGMP general queries.
•
Determine the IGMP last-member query interval.
•
Determine the other querier present interval.
•
Determine the DSCP value for IGMP messages.
Configuring Router-Alert option handling methods
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 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
Step
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
examine 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
Step
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
discard any IGMP message
that does not carry the
Router-Alert option.
igmp require-router-alert
By default, the device does not
examine the Router-Alert option.
