D-Link DSA-3200 Informações Técnicas descarregar pdf (Página 292)

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DGS-3200 Series Layer 2 Managed Gigabit Ethernet Switch Web UI Reference Guide

278

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 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

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

Source Address

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

Ether-Type ARP FCS

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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D-Link DSA-3200 Informações Técnicas Página 292