9
Figure 7 An example of IPv6-to-MAC address mapping
Multicast protocols
NOTE:
•
Generally,
Layer 3 multicast
refers to IP multicast working at the network layer. The related
multicast protocols are Layer 3 multicast protocols, which include IGMP/MLD, PIM/IPv6 PIM,
MSDP, and MBGP/IPv6 MBGP.
Layer 2 multicast refers to
IP multicast working at the data link
layer. The related multicast protocols are Layer 2 multicast protocols, which include IGMP
snooping/MLD snooping, and multicast VLAN/IPv6 multicast VLAN.
•
IGMP snooping, IGMP, multicast VLAN, PIM, MSDP, and MBGP are for IPv4, MLD snooping,
MLD, IPv6 multicast VLAN, IPv6 PIM, and IPv6 MBGP are for IPv6.
•
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
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
1.
Multicast group management protocols
F F 1 E
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
F 3 0 E
0 1 0 1
0 1 0 1
a
F 3 0 E
48-bit MAC address
3 3 3 3
32 bits
mapped
128-bit IPv6 address
…
…
16-bit MAC
address prefix