Multicast - CTC Union ATU-R140 User Manual

Note: The bridge filter table contains 3 hidden rules. These rules are entered automatically by
the system to ensure the user does not "lock" them out of the system. The first rule allows any
and all ARP frames through the system. The second rule allows all IPv4 frames with the
destination MAC address of the bridge to go through. The third rule allows all IPv4 frames
with the source MAC address of the bridge to go through.
Tip: On a windows based machine, to find a MAC address, at a DOS prompt type ipconfig
/all.
The apply button will temporarily save this connection. To make the change permanent you
need to click on Tools (at the top of the page) and select System Commands. At the system
commands page, click on Save All.

4.6.10 Multicast

Multicasting is a form of limited broadcast. UDP is used to send datagrams to all hosts that
belong to what is called a "host group." A host group is a set of zero or more hosts identified
by the same destination IP address. The following statements apply to host groups.
a. Anyone can join or leave a host group at will.
b. There are no restrictions on a host's location.
c. There are no restrictions on the number of members that may belong to a host
group.
d. A host may belong to multiple host groups.
e. Non-group members may send UDP datagrams to the host group.
Multicasting is useful when data needs to be sent to more than one other device. For
instance, if one device is responsible for acquiring data that many other devices need, then
multicasting is a natural fit. Note that using multicasting as opposed to sending the same data
to individual devices uses less network bandwidth.
ATU-R140 ADSL Ethernet USB Router User's Guide
Figure 22 (Bridge Filters)
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