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CAT5, CAT6, Wireless

Category 5 (CAT5) cable is a shielded twisted pair (STP) cable. These STP cables contain four pairs of colored, twisted wires. CAT5 is rated to support 100MB, which is satisfactory for almost every network—most applications today can't even take advantage of the full 100MB. However, I have seen 100MB start to be a bottleneck (negatively effect performance) in servers, so we decided to install CAT6. We plan to be in our new building a long time, and spending the extra dollars on the newest standard gives us growth potential to 1000MB, while continuing to use 100MB today. We added a 1000MB blade in our new switch to support all of the servers. This has given us a noticeable time savings during our nightly backup. Instead of 10 hours, it's taking about 6 to complete the backup. This is great because it's done before our employees show up for work the next morning!

Like CAT5, CAT6 is an STP cable. Installation takes longer, as extra care must be taken when installing CAT6 cable not to untwist more than one-half inch on the ends when terminating the cable. (The twist of the cable allows the data signals to travel at high speeds for long distances.) Some CAT6 cable includes dividers separating each pair for even more protection from signal degradation.

Considering skipping wired and going straight to wireless? We implemented a complementary wireless network that coexists with our wired infrastructure. I could write an entire article on all of the differences in Wi-Fi technologies, but there's not enough room here.

Wireless Ethernet, known in electrical terminology as 802.11, comes in a few flavors:

  • 802.11b is consumer-grade wireless, has been around the longest with the most product available, and supports up to 11MB.

  • 802.11a is commercial grade and supports up to 54MB. That's what we chose to install.

  • 802.11g is a new option, also supporting up to 54MB.

There are compatibility issues with each of these versions. 802.11a operates on the 5 GHz frequency and can't talk to 802.11b on the 2.4 GHz frequency. So you can't (usually) start with 802.11b and then upgrade to 802.11a while keeping the same hardware. Some manufacturers support firmware upgrades to enable access points to communicate at a new speed.

We combated the competing standards by getting dual-band Wi-Fi cards for our notebook users. Dual-band can talk on both the 802.11a and 802.11b networks. Why would we do that? Public access. You've probably heard about public access points for wireless access, such as airports, coffee shops, and Internet cafés that offer free Internet. (I even heard about a pilot test in a San Francisco McDonald's this week.) Most of them offer the old 802.11b signal. When our traveling accountants are out of the office, they can use these public access points. Then, when they're back in the office, they get the best performance currently available, supporting up to 54MB. We still provide 100MB wired network jacks to every office and recommend that they use it, but if they want to roam around the office—to a conference room, for example—they can stay connected to the network while remaining untethered.

802.11g operates in the 2.4 GHz range and is backwardly compatible to 802.11b users. If you have already have an investment in 802.11b, this is probably the best option for you.


Several home cordless phones now operate on the 2.4 GHz range instead of 900 MHz. This can sometimes cause interference with home Wi-Fi use as well as 802.11b and 802.11g. Also, wireless security cameras, such as X-10, operate on 2.4 GHz and can cause interference.

Range is another factor. At 5 GHz, there's much less interference, but the signal doesn't reach as far as with the 2.4 GHz range. (5 GHz is a higher-density bandwidth, but with shorter range.) Using 802.11a access points requires more of them closer together to get equal coverage. There are certainly tradeoffs on each solution. Knowing what they are will help you make the best decision for your company.

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