We talked earlier this week about servers, and undoubtedly some more questions will come up, but let’s go ahead and talk about small-office network infrastructure.
Cable and DSL modems are affordable enough that any small office within the service area of either ought to get one. For the cost of three dialup accounts, you can have Internet service that’s fast enough to be worth having.

I’ve talked a lot about sharing a broadband connection with Freesco, and while I like Freesco, in an office environment I recommend you get an appliance such as those offered by Linksys, US Robotics, D-Link, Netgear, Siemens, and a host of other companies. There are several simple reasons for this: The devices take up less space, they run cooler, there’s no need to wait for them to boot up in case of power failure or someone accidentally unplugging it, and being solid state, theoretically they’re more reliable than a recycled Pentium-75. Plus, they’re very fast and easy to set up (we’re talking five minutes in most cases) and very cheap–under $50. When I just checked, CompUSA’s house brand router/switch was running $39. It’s hard to find a 5-port switch for much less than that. Since you’ll probably use those switch ports for something anyway, the $10-$20 extra you pay to get broadband connection sharing and a DHCP server is more than worth your time.

My boss swears that when he replaced his Linksys combo router/100-megabit switch with a much pricier Cisco combo router/10-megabit switch, the Cisco was faster, not only upstream, but also on the local network. I don’t doubt it, but you can’t buy Cisco gear at the local office supply store for $49.

For my money, I’d prefer to get a 24-port 3Com or Intel switch and plug it into a broadband sharing device but you’ll pay a lot more for commercial-grade 3Com or Intel gear. The cheap smallish switches you’ll see in the ads in the Sunday papers will work OK, but their reliability won’t be as high. Keep a spare on hand if you get the cheap stuff.

What about wireless? Wireless can save you lots of time and money by not having to run CAT5 all over the place–assuming your building isn’t already wired–and your laptop users will love having a network connection anywhere they go. But security is an issue. At the very least, change your SSID from the factory default, turn on WEP (check your manual if it isn’t obvious how to do it), and hard-code your access point(s) to only accept the MAC addresses of the cards your company owns (again, check your manual). Even that isn’t enough necessarily to keep a determined wardriver out of your network. Cisco does the best job of providing decent security, but, again, you can’t buy Cisco gear at your local Staples. Also, to make it easier on yourself, make sure your first access point and your first couple of cards are the same brand. With some work, the variety pack will usually work together. Like-branded stuff always will. When you’re doing your initial setup, you want the first few steps to go as smoothly as possible.

I’d go so far as to turn off DHCP on the wireless segment. Most wardrivers probably have the ability to figure out your network topology, gateway, and know some DNSs. But why make life easier for them? Some won’t know how to do that, and that’ll keep them out. The sophisticated wardriver may decide it’s too much trouble and go find a friendlier network.

Why worry about wireless security? A wardriver may or may not be interested in your LAN. But that’s one concern. And while I don’t care if someone mooches some bandwidth off my LAN to go read USA Today, and I’d only be slightly annoyed if he used it to go download the newest version of Debian, I do care if someone uses my wireless network to send spam to 250,000 of his closest friends, or if he uses my wireless network to visit a bunch of child porn or warez sites.

Enough about that. Let’s talk about how to wire everything. First off, if you use a switched 100-megabit network, you can just wire everything together and not give much thought to anything. But if you’re using hubs or wireless to connect your desktops, be sure to put your servers on 100-megabit switch ports. The servers can then talk to each other at full speed if and when that’s necessary. And a switch port allows them to talk at full speed to a number of slower desktop PCs at once. The speed difference can be noticable.