Adjusting igmp performance, Configuring router-alert option handling methods – H3C Technologies H3C S12500 Series Switches User Manual
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Setting the maximum number of multicast groups that an
interface can join
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 maximum
number of multicast groups
that the interface can join.
igmp group-limit limit
1024 by default.
NOTE:
This configuration takes effect in dynamically joined multicast groups but not in the statically configured
multicast groups.
Adjusting IGMP performance
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 IGMP functions.
•
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 delay for IGMP general queries.
•
Determine the IGMP last-member query interval.
•
Determine the other querier present interval.
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:
•
By default, for the consideration of compatibility, the device does not verify the Router-Alert option.
It processes all the IGMP messages that it received. In this case, IGMP messages are directly passed
to the upper layer protocol, whether the IGMP messages carry the Router-Alert option or not.