HP VPN Firewall Appliances Appendix Protocol Reference

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Figure 42 An example of IPv6-to-MAC address mapping
Multicast protocols
This section provides only general descriptions about applications and functions of the Layer 3 multicast
protocols (IGMP, PIM, IPv6 PIM, and MSDP) supported by the firewalls. For more information about these
protocols, see the related chapters.
Layer 3 multicast protocols include multicast group management protocols and multicast routing
protocols.
Figure 43 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 (namely, a multicast distribution tree) from a data source to multiple
receivers.
In the ASM model, multicast routes include intra-domain routes and inter-domain routes.