HP FlexNetwork 7500 Series Configuration Manual page 19

Layer 3 multicast protocols—IGMP, MLD, PIM, IPv6 PIM, MSDP, MBGP, and IPv6
MBGP.
Layer 2 multicast refers to IP multicast operating at the data link layer.
Layer 2 multicast protocols—IGMP snooping, MLD snooping, PIM snooping, IPv6 PIM
snooping, multicast VLAN, and IPv6 multicast VLAN.
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IPv4 and IPv6 multicast protocols:
For IPv4 networks—IGMP snooping, PIM snooping, multicast VLAN, IGMP, PIM, MSDP,
and MBGP.
For IPv6 networks—MLD snooping, IPv6 PIM snooping, IPv6 multicast VLAN, MLD, IPv6
PIM, and IPv6 MBGP.
This section provides only general descriptions about applications and functions of the Layer 2 and
Layer 3 multicast protocols in a network. For more information about these protocols, see the related
chapters.
Layer 3 multicast protocols
Layer 3 multicast protocols include multicast group management protocols and multicast routing
protocols.
Figure 8 Positions of Layer 3 multicast protocols
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Multicast group management protocols:
Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) protocol
are multicast group management protocols. Typically, they run between hosts and Layer 3
multicast devices that directly connect to the hosts to establish and maintain multicast group
memberships.
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Multicast routing protocols:
A multicast routing protocol runs on Layer 3 multicast devices to establish and maintain
multicast routes and correctly and efficiently forward multicast packets. Multicast routes
constitute loop-free data transmission paths (also known as multicast distribution trees) from a
data source to multiple receivers.
In the ASM model, multicast routes include intra-domain routes and inter-domain routes.
An intra-domain multicast routing protocol discovers multicast sources and builds multicast
distribution trees within an AS to deliver multicast data to receivers. Among a variety of
mature intra-domain multicast routing protocols, PIM is most widely used. Based on the
forwarding mechanism, PIM has dense mode (often referred to as PIM-DM) and sparse
mode (often referred to as PIM-SM).
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