3Com WX3000 operation manual Ethernet multicast MAC address

Class D address range	Description
239.0.0.0 to 239.255.255.255	Administratively scoped multicast addresses, which are for
	specific local use only.

As specified by IANA, the IP addresses ranging from 224.0.0.0 to 224.0.0.255 are reserved for network protocols on local networks. The following table lists commonly used reserved IP multicast addresses:

Table 1-3Reserved IP multicast addresses

Class D address range	Description
224.0.0.1	Address of all hosts
224.0.0.2	Address of all multicast routers
224.0.0.3	Unassigned
224.0.0.4	Distance vector multicast routing protocol (DVMRP) routers
224.0.0.5	Open shortest path first (OSPF) routers
224.0.0.6	Open shortest path first designated routers (OSPF DR)
224.0.0.7	Shared tree routers
224.0.0.8	Shared tree hosts
224.0.0.9	RIP-2 routers
224.0.0.11	Mobile agents
224.0.0.12	DHCP server/relay agent
224.0.0.13	All protocol independent multicast (PIM) routers
224.0.0.14	Resource reservation protocol (RSVP) encapsulation
224.0.0.15	All core-based tree (CBT) routers
224.0.0.16	The specified subnetwork bandwidth management (SBM)
224.0.0.17	All SBMS
224.0.0.18	Virtual router redundancy protocol (VRRP)
224.0.0.19 to 224.0.0.255	Other protocols

Like having reserved the private network segment 10.0.0.0/8 for unicast, IANA has also reserved the network segment 239.0.0.0/8 for multicast. These are administratively scoped addresses. With the administratively scoped addresses, you can define the range of multicast domains flexibly to isolate IP addresses between different multicast domains, so that the same multicast address can be used in different multicast domains without causing collisions.

Ethernet multicast MAC address

When a unicast IP packet is transported in an Ethernet network, the destination MAC address is the MAC address of the receiver. When a multicast packet is transported in an Ethernet network, a

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