Igmp Snooping Supported By The S3700 - Huawei Quidway s3700 series Configuration Manual

Quidway S3700 Series Ethernet Switches
Configuration Guide - Multicast
IGMP Snooping Advantages
The IGMP snooping protocol forwards multicast information only to the specified receivers
through Layer 2 multicast. It has the following advantages:
l
l
l

2.2 IGMP Snooping Supported by the S3700

This section describes IGMP snooping features supported by the S3700.
IGMP Snooping
The S3700 supports VLAN-based IGMP snooping.
IGMP snooping implements Layer 2 multicast and controls multicast data forwarding by
listening to multicast protocol packets sent between an upstream router and a downstream host
and maintaining downstream interface information.
You can configure user hosts to join a multicast group statically so that user hosts can steadily
receive multicast data packets.
You can also enable the S3700 to actively send IGMP Query messages so that the S3700 can
rapidly sense a Layer 2 network topology change and forward multicast data based on the new
topology, preventing multicast services from being interrupted.
Prompt Leave
When an interface of the S3700 receives an IGMP Leave message to leave a specified multicast
group, the S3700 deletes the interface from the downstream interface list of this multicast group
immediately. This is called prompt leave of a multicast group member. This feature is used in
the multicast IPTV scenario where one interface of the S3700 is commonly connected to only
one user host. Therefore, the prompt leave function shortens the speed at which the user switches
channels.
IGMP snooping prompt leave has the following advantages:
l
l
IGMP Snooping Querier
On a multicast network running IGMP, there should be a Layer 3 multicast device functioning
as an IGMP querier to send IGMP Query messages and create and maintain multicast forwarding
entries for normal multicast data forwarding.
If a multicast network does not have Layer 3 devices and Layer 2 devices do not support IGMP,
no IGMP querier can be configured. To solve such a problem, configure an IGMP snooping
querier on the Layer 2 device so that the Layer 2 device can create and maintain multicast
forwarding entries at the data link layer, implementing multicast data forwarding.
Issue 01 (2011-10-26)
Reducing broadcast packets on Layer 2 networks, and thus saving network bandwidth
Enhancing the security of multicast information
Performing accounting for each host independently
Reducing response delay
Saving the network bandwidth that is used by various types of messages
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
2 IGMP Snooping Configuration
8