D-Link DGS-3700 user manual Destination address Source address Ether-type, Port2 00-20-5C-01-22-22

DGS-3700-12/DGS-3700-12G Series Layer 2 Gigabit Ethernet Switch User Manual

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 the Ethernet frame again and sent back to the sender. The ARP reply is in a form of Unicast communication.

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
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 the Forwarding Table. The switch will learn PC B’s MAC and update its Forwarding Table.

Forwarding Table

Port1 00-20-5C-01-11-11

Port2 00-20-5C-01-22-22

261