Internet Core Protocols: The Definitive Guide

Lots of ARP Requests from Network Clients

If you have a lot of ARP requests from network clients, then you probably have too small of a cache on the client systems. Most client systems have a very small ARP cache, and will gladly flush through it on a continuous basis if you force them to connect to a multitude of servers. Either refer to your system documentation for instructions on how to increase the ARP cache, or else replace the IP software you have with something better.

Increasing the size of the ARP cache may cause other problems for the client, due to an increased demand for memory, CPU time, and other resources. Another option for you to consider is to consolidate a multitude of servers into a single large system.

Frequent flushing of cache data at the client can also result when ARP timeout values are set too low. If your clients only check email every thirty minutes, but the ARP timers expire after twenty minutes, then the clients will have to issue ARP requests every time they check their mail. On a large network with hundreds of devices per segment, this activity can generate a substantial amount of traffic. You may want to either lengthen the cache timeout values or implement a periodic Gratuitous ARP process on the servers.