IPv6 Multicast Addresses

1. Local Scope Multicast Addresses

• Multicast addresses that begin with FF02::/16 have a link-local scope i.e., routers will not forward these packets outside the local subnet.
• Multicast addresses that begin with FF08::/16 have an organizational-local scope i.e., packets sent to these addresses are forwarded throughout the enterprise but not out the internet.
• Command to verify the Local-scope Multicast addresses is show ipv6 interface G0/0

Key IPv6 Local-scope Multicast Addresses

Multicast address	Used to send data to	IPv4 equivalent
FF02::1	All nodes (All IPv6 interfaces that are on the link)	A subnet broadcast address
FF02::2	All routers (All IPv6 router interfaces on the link)	None
FF02::5	All OSPFv6 routers	224.0.0.5
FF02::6	All OSPFv6-Designated Routers	224.0.0.6
FF02::9	All RIPng routers	224.0.0.9
FF02::A	All EIGRPv6 routers	224.0.0.10
FF02::1:2	All DHCPv6 Relay Agent Routers	None

2. Solicied-Node Multicast Addresses

• It is also a Link-local multicast address.
• If more than one host in a subnet happens to have equal values in the last six hex digits of its unicast addresses, they calculate and use the same solicited-node multicast address. Some protocols need this kind of logic of sending one multicast packet to all hosts that have these similar unicast IPv6 addresses.
• For each unicast address on each interface, the device must calculate its Solicited-node multicast address and listen for packets sent to those addresses. One for Global unicast address and other for Unique local address.

Solicited-Node Multicast Address Format

Predefined by RFC - 32 Hex. Digits	Last 6 Hex. Digits of unicast address
FF02:0000:0000:0000:0000:0001:FF	_ _ : _ _ _ _