D-Link xStack Reference Manual page 292

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xStack DGS-3200 Series Layer 2 Managed Gigabit Ethernet Switch Web UI Reference Guide
When the switch floods the frame of ARP request to the network, all PCs will receive and examine the frame but only PC B will
reply the query as the destination IP matched (see Figure 3).
Figure 3
When PC B replies to the ARP request, its MAC address will be written into "Target H/W Address" in the ARP payload shown in
Table 3. The ARP reply will be then encapsulated into an Ethernet frame again and sent back to the sender. The ARP reply is in a
form of Unicast communication.
Table 3. ARP Payload
H/W Protocol H/W Protocol Operation Sender Sender Target Target
Type Type Address Address H/W Address Protocol H/W Address Protocol
Length Length Address Address
ARP reply 00-20-5C-01-11-11 10.10.10.1 00-20-5C-01-22-22 10.10.10.2
When PC B replies to the query, the "Destination Address" in the Ethernet frame will be changed to PC A's MAC address. The
"Source Address" will be changed to PC B's MAC address (see Table 4).
Table 4. Ethernet Frame Format
Destination Address Source Address Ether-Type ARP FCS
00-20-5C-01-11-11 00-20-5C-01-22-22
The switch will also examine the "Source Address" of the Ethernet frame and find that the address is not in the Forwarding Table.
The switch will learn PC B's MAC and update its Forwarding Table.
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