xStack
®
DGS-3200 Series Layer 2 Gigabit Ethernet Managed Switch
Figure 2
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
Type
Protocol
Type
H/W
Address
Length
Protocol
Address
Length
Operation Sender
H/W Address
Sender
Protocol
Address
Target
H/W Address
Target
Protocol
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 th e query, the “Destination Address” in the Ethernet frame will be ch anged to PC A’s M AC address. The
“Source Address” will be changed to PC B’s MAC address (see Table 4).
Table 4. Ethernet Frame Format
Destination Address
00-20-5C-01-11-11
Source Address
00-20-5C-01-22-22
Ether-Type ARP FCS
258
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