168.3.2
L2 = 0800:0333:2222
L3 = 192.168.4.1
L2 = 0800:0333:1111
L3 = 192.168.4.2
L2 = 0800:0222:1111
ARP
Request
ARP
Request
Router: I just received the ARP request. Let
me add host 192.168.3.1 to my ARP table
with a MAC address of 0800:0222:2222.
SRC MAC
0800:0222:2222
DST MAC
Broadcast
Packet
Parking Lot
Exploring the Packet Delivery Process 299
Figure 4-36 Router Responds to ARP Request
The destination host receives the ARP request. The device can now form a Layer 2 frame
to put on the wire. Because the destination host is off network, the Layer 3 address will be
mapped to the router??™s MAC address in the frame. Figure 4-37 shows this step.
Figure 4-37 Off-Net Layer 3 Mapped to Gateway Layer 2
The pending frame is sent with the local host IP address and MAC address as the source.
However, the destination IP address is that of the remote host, but the destination MAC
address is that of the default gateway. Figure 4-38 shows the frame being sent to the router.
Figure 4-38 Frame Sent to Router
L3 = 192.168.3.1
L2 = 0800:0222:2222
L3 = 192.168.3.2
L2 = 0800:0333:2222
L3 = 192.168.4.1
L2 = 0800:0333:1111
L3 = 192.168.4.2
L2 = 0800:0222:1111
ARP
Reply
Router: I??™ll send an ARP reply that I am
192.
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