3Com MSR 50 Series Configuration Manual page 1093

This section provides only general descriptions about applications and functions of
the Layer 2 and Layer 3 multicast protocols in a network. For details of these
protocols, refer to "MPLS L2VPN Configuration" on page 1425
Configuration" on page
Currently, the MSR series routers do not support IGMP Snooping, multicast VLAN,
IPv6 multicast VLAN and MLD Snooping.
Layer 3 multicast protocols
Layer 3 multicast protocols include multicast group management protocols and
multicast routing protocols.
are in a network.
Figure 322 Positions of Layer 3 multicast protocols
Receiver
IGMP/MLD
PIM/IPv6 PIM
1 Multicast management protocols
Typically, the internet group management protocol (IGMP) or multicast listener
discovery protocol (MLD) is used between hosts and Layer 3 multicast devices
directly connected with the hosts. These protocols define the mechanism of
establishing and maintaining group memberships between hosts and Layer 3
multicast devices.
2 Multicast routing protocols
A multicast routing protocol runs on Layer 3 multicast devices to establish and
maintain multicast routes and forward multicast packets correctly and efficiently.
Multicast routes constitute a loop-free data transmission path from a data source
to multiple receivers, namely, a multicast distribution tree.
In the ASM model, multicast routes come in intra-domain routes and inter-domain
routes.
An intra-domain multicast routing protocol is used to discover multicast
■
sources and build multicast distribution trees within an AS so as to deliver
multicast data to receivers. Among a variety of mature intra-domain multicast
routing protocols, protocol independent multicast (PIM) is a popular one. Based
1459.
Figure 322 describes where these multicast protocols
AS 1
MSDP
Source
Multicast Architecture
and "MPLS L3VPN
Receiver AS 2
IGMP/MLD
PIM/IPv6 PIM
IGMP/MLD
Receiver
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