I've received quite a few letters from readers who want me to write about the performance they can expect from their home-networking choices. They generally complain that the blurb on a product's box doesn't accurately represent the product's behavior. And when I wrote about the differences between a switch and a hub, many readers sent me links to products and asked whether the products were switches or hubs. So following are guidelines for what you can expect from various small office/home office (SOHO) networking products.
How can I tell a switch from a hub?
When you're looking for a switch, key words to look for on the package are "switching fabric," "non-blocking," and "full-bandwidth to each port." High-quality switches will also include a Gigabit Ethernet uplink port, which lets you connect 100Mbps clients to a server running 1Gbps. If the product package uses terms such as "auto sensing" and uses no switch-specific terms, the product isn't a switch. Some packaging might refer to a product as a hub or a switch, but if the product has a switching fabric and allows full 100Mbps bandwidth dedicated to each port, it's functionally a switch.
Why doesn't my 802.11b device work more than 20 feet from my wireless access point?
Although the product's package might promise a connectivity range that encompasses your neighbor's home, the reality is that the range measurement applies only to an open area. If you have a 1-acre warehouse with no internal structures, a single access point in the middle will likely give you full coverage. If you have a typical house, your wireless system will encounter interference from a variety of sources. For example, an old stone-wall house will prevent the network signal from propagating very far, as will a new steel-studded wall. Electrical wiring and aluminum-backed insulation will also shorten household ranges. And other devices—such as portable phones and microwave ovens—that operate in the 2.4GHz band will also cause interference with 802.11b products.
The manufacturer claims my wireless network will run at 11Mbps; why does it seem so much slower?
Any network protocol has significant overhead activity that can make the network run slower than the advertised speed, especially new wireless technologies that need to coexist with old wireless devices. In reality, an 11Mbps 802.11b connection's peak throughput will reach 6Mbps reliably, although sustained throughput over time will be less than 6Mbps. Even the 54Mbps 802.11a specification will provide an actual speed of only about 35Mbps. Wired networks also have some overhead, but generally under 10 percent or so.
What does Cat 5 mean?
A set of standards applies to cables in wired networks. Category 5 (Cat 5) wiring will support 100Mbps Ethernet. If you plan to pull wires through your home or office, your local building codes might require you to use specific grades of wire beyond the measurements for network performance (e.g., plenum-grade wire certified for pulling through office air-conditioning ducts). Check with local building authorities before you embark on a large network-wiring project.
In this article, I've covered some of the most common questions I regularly receive. Keep sending your questions, and we'll keep answering them.