Introduction To Layer 2 Multicast; Layer 2 Multicast Features Supported By The S9300 - Huawei Quidway S9300 Configuration Manual - Multicast

1 Layer 2 Multicast Configuration

1.1 Introduction to Layer 2 Multicast

This section describes the functions and advantages of Layer 2 multicast.
To correctly transmit multicast packets on a local physical network, you need to provide link
layer multicast, namely, Layer 2 multicast, in addition to the network layer IP multicast.
Static Layer 2 Multicast
When multicast packets are transmitted on an Ethernet network, the destination of packets is a
group of unspecific members instead of a specific receiver. Therefore, multicast forwarding
entries cannot be generated when multicast packets are forwarded to the link layer from the IP
layer. As a result, the multicast packets are broadcast on the link layer. This wastes the bandwidth,
makes the accounting of user services inconvenient, and poses a threat to information security.
When the S9300 is deployed between a router and user hosts and needs to apply the Layer 2
forwarding feature, you can configure the static Layer 2 multicast, that is, configure the
forwarding entries manually. In this manner, multicast data is forwarded to the users who needs
to receive the multicast data within a long time.
Multicast VLAN Replication
In the traditional multicast mode, when users in different virtual local area networks (VLANs)
require data of the same multicast source, a switch replicates multicast packets for each VLAN
and sends the multicast packets to all the VLANs. This wastes the bandwidth and imposes extra
burden on routers.
The multicast VLAN replication function is introduced to solve this problem. You can configure
a multicast VLAN on the S9300 and configure other VLANs as user VLANs of the multicast
VLAN. When users in different VLANs require data of the same multicast source, the upstream
router sends multicast packets only to the multicast VLAN, and do not needs to replicate
multicast packets for each VLAN.
IGMP Snooping
Internet Group Management Protocol (IGMP) snooping monitors the multicast protocol packets
exchanged between a router and hosts to maintain information about the outgoing interface of
multicast packets. In this way, IGMP snooping manages and controls forwarding of multicast
data packets to implement Layer 2 multicast.

1.2 Layer 2 Multicast Features Supported by the S9300

This section describes the Layer 2 multicast features supported by the S9300.
Static Layer 2 Multicast
You can add an interface to a multicast group statically. This feature is called static Layer 2
multicast. It has the following advantages:
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Preventing attacks from protocol packets
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Quidway S9300 Terabit Routing Switch
Configuration Guide - Multicast
Issue 01 (2009-07-28)