Orion A10E - Multicast Address

Orion Networks
A10E/A28E/A28F Configuration Guide
5 Multicast
Orion Networks
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All hosts joined a multicast group will become a member of the multicast group. Multicast
group members are dynamic, hosts can join or leave multicast group at any time. Group
members may be widely distributed in any part of the network.
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Multicast source
Multicast source refers to a server which regards multicast group address as the destination
address to send IP packet. A multicast source can send data to multiple multicast groups;
multiple multicast sources can send to a multicast group.
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Multicast router
The router that supports Layer 3 multicast is called the multicast router. Multicast router can
achieve multicast routing, guide multicast packet forwarding and provide multicast group
management function to distal network segment connecting with users.
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Router interface
The router interface is also called source interface. It refers to the interface toward multicast
router between multicast router and the host. The A10E/A28E receives multicast packets from
this interface.
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Member interface
Known as the receiving interface, the member interface is the interface toward host between
multicast router and the host. The A10E/A28E sends multicast packets from this interface.
Multicast address
In order to make multicast source and multicast group members communicate across the
Internet, you need to provide network-layer multicast address and link-layer multicast address,
i.e. IP multicast address and multicast MAC address. Note: multicast address only can be
destination address, but not source address.
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IP multicast address
IANA (Internet Assigned Numbers Authority) assigns Class D address space to IPv4 multicast;
the range of IPv4 multicast address is from 224.0.0.0 to 239.255.255.255.
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Multicast MAC address
When Ethernet transmits unicast IP packet, the destination MAC address will use the recipient
MAC address. However, when multicast packets are in transmission, the destination is no
longer a specific receiver, but a group with uncertain member, so it needs to use multicast
MAC address.
Multicast MAC address for link layer identifies the receiver of the same multicast group.
According to IANA, the high 24-bit of multicast MAC address are 0x01005E, the 25-bit is
fixed 0, the 23-bit corresponds to the low 23-bit of IPv4 multicast address.
The mapping relation between IP multicast address and MAC address is shown below.