Introduction

The Linux kernel makes available a large set of kernel variables that can be tuned to configure the system for functionality and optimum performance. Additionally, the kernel makes a large amount of information about the system available to the user. Utilizing this information to ensure the system's health and detect problems in configuration and the network are critical performance tasks.

The predominant networking environment that applications run on is the TCP/IP (transport control protocol/Internet protocol) network protocol stack, with IP version 4 currently the standard. Linux is widely used as a platform to host network infrastructure services such as web servers, mail servers, and domain name system (DNS) servers, which makes networking performance an important consideration for system administrators.

Although this chapter covers the more important variables for network tuning, it is by no means exhaustive. Documentation available in the Documentation directory of the kernel source tree, as well as system man pages, can provide more information. The information provided here is applicable to the 2.4 through 2.6 Linux kernel versions unless otherwise noted.

Let's begin by examining the network protocol stack.