Cabletron Systems 9032578-05 manual Configuring Address Resolution Protocol ARP

Chapter 8: IP Routing Configuration Guide

Configuring Address Resolution Protocol (ARP)

The SSR allows you to configure Address Resolution Protocol (ARP) table entries and parameters. ARP is used to associate IP addresses with media or MAC addresses. Taking an IP address as input, ARP determines the associated MAC address. Once a media or MAC address is determined, the IP address/media address association is stored in an ARP cache for rapid retrieval. Then the IP datagram is encapsulated in a link-layer frame and sent over the network.

Configuring ARP Cache Entries

To create an ARP entry for the IP address 10.8.1.2 at port et.4.7 for 15 seconds:

ssr# arp add 10.8.1.2 mac-addr 08:00:20:a2:f3:49 exit-port et.4.7 keep-time 15

To create a permanent ARP entry for the host nfs2 at port et.3.1:

ssr(config)# arp add nfs2 mac-addr 080020:13a09f exit-port et.3.1

To remove the ARP entry for the host 10.8.1.2 from the ARP table:.

ssr# arp clear 10.8.1.2

To clear the entire ARP table.

ssr# arp clear all

If the Startup configuration file contains arp add commands, the Control Module re-adds the ARP entries even if you have cleared them using the arp clear command. To permanently remove an ARP entry, use the negate command or no command to remove the entry.

Unresolved MAC Addresses for ARP Entries

When the SSR receives a packet for a host whose MAC address it has not resolved, the SSR tries to resolve the next-hop MAC address by sending ARP requests. Five requests are sent initially for each host, one every second.

You can configure the SSR to drop packets for hosts whose MAC addresses the SSR has been unable to resolve. To enable dropping of packets for hosts with unresolved MAC addresses:

ssr# arp set drop-unresolved enabled

SmartSwitch Router User Reference Manual 81