Nortel Networks NN47200-503 manual Address Resolution Protocol ARP, Step Action, End

IP routing 21

Step Action

1Enable IP routing globally.

2Assign an IP address to the specific VLAN or brouter port.

3Enable IP routing on the interface.

—End—

Refer to subsequent chapters in this document for detailed instructions on configuring IP routes.

Address Resolution Protocol (ARP)

Address Resolution Protocol (ARP)

Network stations using the IP protocol need both a physical address and an IP address to transmit a packet. If a network station knows only a network host’s IP address, the Address Resolution Protocol (ARP) enables the network station to determine a network host’s physical address and bind the 32-bit IP address to a 48-bit MAC address. A network station can use ARP across a single network only, and the network hardware must support physical broadcasts.

If a network station wants to send a packet to a host but knows only the host’s IP address, the network station uses ARP to determine the host’s physical address as follows:

1.The network station broadcasts a special packet, called an ARP request, that asks the host at the specified IP address to respond with its physical address.

2.All network hosts receive the broadcast message.

3.Only the specified host responds with its hardware address.

4.The network station then maps the host’s IP address to its physical address and saves the results in an address resolution table for future use.

5.The network station’s ARP table displays the association of the known MAC addresses to IP addresses.

Note: The default timeout value for ARP entries is 6 hours.

Static ARP entries can be created and individual ARP entries deleted.

Nortel Ethernet Routing Switch 5500 Series

Configuration-IP Routing Protocols

NN47200-503 03.01 Standard

5.127 August 2007

Copyright © 2005-2007, Nortel Networks