Best Networking Tweaks for Linux

A Linux system can be tweaked to a degree Windows users may envy (or fear) especially for networking. Tweaking a Linux box for networking is a bit more mundane than other platforms: there are specific driver settings one can work with but its best flexibility comes from a mix of OS-level modifications and adherence to different RFCs.

Conservative 1000 packets

Software buffers for network adapters on Linux start off at a conservative 1000 packets. Network researchers and scientists have mucked around with this, and figured out that we should be using 10,000 for anything decent on a LAN; more if you're running GB or 10GE stuff. Slow interfaces, such as modems and WAN links, can default to 0-100, but don't be afraid to bump it up towards 1000 and see if your performance improves. Bumping up this setting does use memory, so be careful if you're using an embedded router or something (I've used 10,000 on 16MB RAM OpenWRT units, no prob).

You can edit /etc/rc.local, add an "up" command to /etc/networking/interfaces, or whatever your distribution suggests and it's best to put a command like this at startup.

This file governs default behavior for many network and file operation settings on Linux and other *nix-based systems. If you deploy Ubuntu or Fedora systems, you'll notice they will add their own tweaks (usually security or file-oriented) to the file: don't delete those, unless you read up on them, or see any that are contradicted by the suggested additions here...

4. The latency setting is 1 if you prefer more packets vs bandwidth, or 0 if you prefer bandwidth. More packets are ideal for things like Remote Desktop and VOIP: less for bulk downloading.

For further study, there's a great IBM article regarding network optimizations: it was my source for some of these settings, as well as following numerous articles on tweaking Linux networking over the years (SpeedGuide has one from 2003).

Windows Vista and newer gained Compound TCP as an alternative to standard TCP Reno. Linux Kernel 2.6 has had numerous mechanisms available to it for some time: 2.6.19 defaulted to CUBIC which was supposed to work well over "long links." My two personal favorites: TCP Westwood + and TCP Illinois. But you can dig in, look at different research papers online, and see what works best for your environment.

There you have it -- some of my favorite Linux tweaks for networking. I'm interested in hearing how these worked for you. If you have some of your own, please post a comment and share them with other readers.