D-Link DES-3326SR, User Manual

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DES-3326SR Layer 3 Fast Ethernet Switch User’s Guide
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the request. If it is, the local ARP replies by sending its MAC IP
address pair back to the requesting system. Second, if the
local computer is not the target of the request, the packet is
dropped.
Multicasting
Multicasting is a group of protocols and tools that enable a
single source point to send packets to groups of multiple
destination points with persistent connections that last for
some amount of time. The main advantage to multicasting is a
decrease in the network load compared to broadcasting.
Multicast Groups
Class D IP addresses are assigned to a group of network
devices that comprise a multicast group. The four most
significant four bits of a Class D address are set to “1110”. The
following 28 bits is referred to as the ‘multicast group ID’.
Some of the range of Class D addresses are registered with the
Internet Assigned Numbers Authority (IANA) for special
purposes. For example, the block of multicast addresses
ranging from 224.0.0.1 to 224.0.0.225 is reserved for use by
routing protocols and some other low-level topology discovery
and maintenance protocols.
Figure 5-14. Class D Multicast Address