D-Link DGS-3700 - page 272

DGS-3700-12/DGS-3700-12G Series Layer 2 Gigabit Ethernet Switch User Manual
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When PC B replies to the ARP request, its MAC address will be written into “T arget H/W Address” in the ARP payload
shown in Table-3. The ARP reply will be then encapsulated into the Ethernet frame again and sent back to the sender.
The ARP reply is in a form of Unicast communication.
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
AR P reply 00-20-5C-01-11-11 10.10.10.1 00-20-5C-01-22-22 10.10.10.2
Table – 3 (ARP Payload)
When PC B replies 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).
Destination address Source address
Ether-type ARP FCS
00-20-5C-01-11-11 00-20-5C-01-22-22
Table – 4 (Ethernet frame format)
The switch will also examine the “Source Address” of the Ethernet frame and find that the address is not in t he
Forwarding Table. The switch will learn PC B’s MAC and update its Forwarding Table.
Port1 00-20-5C-01-11-11
Port2 00-20-5C-01-22-22
Forwarding Table