ZyXEL Communications Prestige 794M - Manual (Page 29)

Prestige 794M User’s Guide
29 Chapter 2 The Web Configurator
2.6 ARP Table
Address Resolution Protocol (ARP) is a protocol for mapping an Internet Protocol address (IP
address) to a physical machine address, also known as a Media Access Control (MAC)
address, on the local area network. An IP (version 4) address is 32 bits long. In an Ethernet
LAN, MAC addresses are 48 bits long. The ARP table maintains an association between each
MAC address and its corresponding IP address.
2.6.1 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.
To view the ARP table, click Status and ARP Table in the navigation panel.
Figure 9 Status: ARP Table
RFC1483 WAN
Link
This field displays the VCI and VPI number and the number of packets received/
transmitted. Click this label to display detailed information.
Ethernet This field displays the number of packets received/transmitted. Click this label to
display detailed information.
SAVE CONFIG Click SAVE CONFIG to save the changes.
RESTART Click RESTART to reboot the device. All unsaved changes will be lost.
LOGOUT Click LOGOUT to exit from the web configurator. All unsaved changes will be lost.
Table 3 Status (continued)
LABEL DESCRIPTION