Understanding Linux Network Internals

When a Feature Is Offered as a Patch

The kernel networking code is continuously evolving. Not only does it integrate new features, but existing components sometimes undergo design changes to achieve more modularity and higher performance. This obviously makes Linux very attractive as an embedded operating system for network appliance products (routers, switches, firewalls, load balancers, etc.).

Because anyone can develop a new feature for the Linux kernel, or extend or reimplement an existing one, the greatest thrill for any "open" developer is to see her work make it to the official kernel release. Sometimes, however, that is not possible or it may take a long time, even when a project has valuable features and is well implemented. Common reasons include:

• The code may not have been written following the guidelines in Documentation/CodingStyle.

• Another major project that provides the same functionality has been around for some time and has already received the green light from the Linux community and from the key kernel developers that maintain the associated kernel area.

• There is too much overlap with another kernel component. In a case like this, the best approach is to remove the redundant functionality and use existing functionality where possible, or to extend the latter so that it can be used in new contexts. This situation underlines the importance of modularity.

• The size of the project and the amount of work required to maintain it in a quick-changing kernel may lead the new ...