Chapter 6 Router
LTE4506 User’s Guide
67
6.14.1 How ARP Works
When an incoming packet destined for a host device on a local area network arrives at the device, the
device's ARP program looks in the ARP table and, if it finds the address, sends it to the device.
If no entry is found for the IP address, ARP broadcasts the request to all the devices on the LAN. The
device fills in its own MAC and IP address in the sender address fields, and puts the known IP address of
the target in the target IP address field. In addition, the device puts all ones in the target MAC field
(FF.FF.FF.FF.FF.FF is the Ethernet broadcast address). The replying device (which is either the IP address of
the device being sought or the router that knows the way) replaces the broadcast address with the
target's MAC address, swaps the sender and target pairs, and unicasts the answer directly back to the
requesting machine. ARP updates the ARP table for future reference and then sends the packet to the
MAC address that replied.
Use the following screen to configure or view the IPv4-to-MAC address mappings for the LAN. To access
this screen, click Router > Firewall > ARP.
Figure 43 Router > Firewall > ARP
The following table describes the labels in this screen.
Table 34 Router > Firewall > ARP
LABEL DESCRIPTION
ARP Settings
Enable ARP
attack
protecting
Select the check box to allow the ARP inspection to filter unauthorized ARP (Address Resolution
Protocol) packets on the network.
LAN IP/MAC
Binding List
This field displays how many entries you display on this page.
Add New Click Add New to create a new entry.
This field displays the ARP table entry number.
IP Address This field displays the learned IP address of the device connected to the LTE4506.
MAC Address This field displays the MAC address of the device with the listed IP address.
Action Click Edit to go to the screen where you can edit the entry.
Click Delete to remove the ARP inspection entry.
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