In previous tips, I've mentioned "Open Source" products quite a bit, especially those that provide network management features or IP Telephony functionality. But until recently, open source routers and switches have been lurking quietly beneath pop network culture's radar. This is not because none exist, or because they aren't adequately functional. In fact, quite the opposite is true. Rather, they haven't gained much traction for several...
First, second and third is hardware, hardware, hardware. First, in the sorts of places likely to be on the leading edge of adopting open source, routers are commonly used for terminating WAN circuits, and this hardware isn't often found on PC platforms. It exists, of course. It's just not widely known or for that matter, trusted. And frankly, it's probably cheaper to buy a more common model used than electronics for a T1 circuit in a PCI form factor, if economy is what's driving you to open source.
Second, the specialized hardware from the likes of Cisco and Nortel and others offers lots of technologies like CEF switching, which really boosts overall performance. Even the latest, greatest 3+ GHZ multi-CPU server and gigabytes of RAM, will have a great deal of difficulty competing with custom ASICs that, for instance, allow you to push your Access-Control List processing down into hardware, or offer very advanced buffering and queuing techniques.
Third, network hardware is often about port density. Support for 24 or 48 10/100 Ethernet ports just isn't an option on PCs for a long list of reasons.
However, that was then, and open source is recently finding its way into a couple of niches. One niche was created by the sudden availability of cheap 10/100/1000 copper and fiber Gigabit Ethernet cards. An example of a good use for this might be a group of doctors with several offices in a large city, and a need for high-bandwidth to support imaging (like X-rays stored to disk). They could use open-sourced, PC-based routers to terminate Metro-Ethernet MAN services.
Another good niche for this is LAN hardware that often supports higher-layer services, like firewalls and VPNs. A PC with 3 to 5 gigabit cards makes a very cost-effective DMZ router.
Of course, before you get the wrong impression about the landscape, remember that Nortel has been licensing their router code as part of an "Open IP" strategy since 2000, and quite a bit of Linksys (a division of Cisco) code is GPL.
Tom Lancaster, CCIE# 8829 CNX# 1105, is a consultant with 15 years experience in the networking industry, and co-author of several books on networking, most recently, CCSPTM: Secure PIX and Secure VPN Study Guide published by Sybex.