IBM Support

Clearing a Specific ARP Cache Entry



This document provides information about removing ARP Cache entries from the ARP Table.

Resolving The Problem

At times, network devices can be replaced with new hardware or a new Network Interface Card (NIC) and retain the original TCP/IP address. When the new hardware device or NIC is powered on, connectivity might not occur because of an old ARP cache entry in the IBM® iSeries™ family of servers ARP table. Until the ARP cache entry with the old MAC address and TCP/IP address is removed, communications over TCP/IP will fail.

The easiest way to clear this entry is to use iSeries Navigator. The following steps outline the procedure for clearing an ARP Cache Entry:

1Open iSeries Navigator.
2Expand Network.
3Expand TCP/IP Configuration.
4Expand IPv4.
5Click on Interfaces.
6Right-click on the iSeries family's TCP/IP Interface and select ARP.

Note: The ARP option will work only for an ACTIVE interface.

A new window, similar to the one below, will appear:

7Left-click on the TCP/IP address in question to highlight it, and click on Delete Entry:

8Click Apply.

After the ARP Cache Entry is removed, try the connection again. If the connection continues to fail, a communications trace is recommended for troubleshooting.

Note: The duration that an entry resides in the ARP cache is defined by the ARP Cache Timeout (ARPTIMO) value in the CHGTCPA command.

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Document Information

Modified date:
18 December 2019