9
Multicast protocols
Multicast protocols include the following categories:
•
Layer 3 and Layer 2 multicast protocols:
{
Layer 3 multicast refers to IP multicast operating at the network layer.
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.
•
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
•
Multicast group management protocols:
Typically, the Internet Group Management Protocol (IGMP) or Multicast Listener Discovery
(MLD) protocol is used between hosts and Layer 3 multicast devices that directly connect to the
hosts. These protocols define the mechanism of establishing and maintaining group
memberships between hosts and Layer 3 multicast devices.
•
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 loop-free data transmission paths from a data source to multiple receivers, that is, a
multicast distribution tree.
