Netgear GS418TPP User Manual - Page 242

ProSAFE 8-Port or 16-Port Gigabit Smart Managed Switch Model GS418TPP, GS510TLP, and GS510TPP Configure Address Resolution Protocol The Address Resolution Protocol (ARP) associates a Layer 2 MAC address with a Layer 3 IPv4 address. The switch supports both dynamic and manual ARP configurations. With manual ARP configuration, you can statically add entries into the ARP table. ARP is a necessary part of the Internet Protocol (IP) and is used to translate an IP address to a media (MAC) address, defined by a local area network (LAN) such as Ethernet. A station that must send an IP packet must learn the MAC address of the IP destination, or of the next hop router if the destination is not on the same subnet. This is achieved by broadcasting an ARP request packet, to which the intended recipient responds by unicasting an ARP reply containing its MAC address. Once learned, the MAC address is used in the destination address field of the Layer 2 header prepended to the IP packet. The ARP cache is a table maintained locally in each station on a network. The switch learns ARP cache entries by examining the source information in the ARP packet payload fields, regardless of whether it is an ARP request or response. Thus, when an ARP request is broadcast to all stations on a LAN segment or virtual LAN (VLAN), each recipient can store the sender's IP and MAC address in its respective ARP cache. The ARP response, being unicast, is normally seen only by the requestor, who stores the sender information in its ARP cache. Newer information always replaces existing content in the ARP cache. Devices can be moved in a network, which means that the IP address that was at one time associated with a certain MAC address is now found using a different MAC address, or it disappeared from the network altogether (for example, it was reconfigured, disconnected, or powered off). This leads to stale information in the ARP cache unless entries are updated in reaction to new information seen on the network, periodically refreshed to determine if an address still exists, or removed from the cache if the entry was identified as a sender of an ARP packet during the course of an ageout interval, usually specified through configuration. Display Basic ARP Cache You can display ARP entries in the ARP cache. The table lists the remote connections most recently seen by this switch.  To display ARP entries in the ARP cache: 1. Connect your computer to the same network as the switch. You can use a WiFi or wired connection to connect your computer to the network, or connect directly to a switch that is off-network using an Ethernet cable. 2. Launch a web browser. 3. In the address field of your web browser, enter the IP address of the switch. If you do not know the IP address of the switch, see Change the Default IP Address of the Switch on page 11. The login window opens. 4. Enter the switch's password in the Password field. Configure Routing 242