Specifications

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Cisco MWR 2941 Mobile Wireless Edge Router Software Configuration Guide, Release 12.2(33)MRB
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Chapter 1 Cisco MWR 2941 Router Overview
Features
Figure 6 Multicast Transmission
IP Multicast Group Addressing
A multicast group is identified by its multicast group address. Multicast packets are delivered to that
multicast group address. Unlike unicast addresses that uniquely identify a single host, multicast IP
addresses do not identify a particular host. To receive the data sent to a multicast address, a host must
join the group that address identifies. The data is sent to the multicast address and received by all the
hosts that have joined the group indicating that they wish to receive traffic sent to that group. The
multicast group address is assigned to a group at the source. Network administrators who assign
multicast group addresses must make sure the addresses conform to the multicast address range
assignments reserved by the Internet Assigned Numbers Authority (IANA).
IP Class D Addresses
IP multicast addresses have been assigned to the IPv4 Class D address space by IANA. The high-order
four bits of a Class D address are 1110. Therefore, host group addresses can be in the range 224.0.0.0 to
239.255.255.255. A multicast address is chosen at the source (sender) for the receivers in a multicast
group.
Note The Class D address range is used only for the group address or destination address of IP multicast
traffic. The source address for multicast datagrams is always the unicast source address.
Receiver A
Multicast
Group
Receiver B
Receiver C
Receiver D
Source
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