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Maintenance & Testing: Testing in a wireless world

JUST LIKE IN A WIRED NETWORK, THE WIRELESS NETWORK CLIENT ISSUES MUST BE FIXED WHEN ISSUES ARISE.A wireless world is upon us. Users' preference for untethered technology is obvious. Most PDAs and 70 p...


March 1, 2003  


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JUST LIKE IN A WIRED NETWORK, THE WIRELESS NETWORK CLIENT ISSUES MUST BE FIXED WHEN ISSUES ARISE.

A wireless world is upon us. Users’ preference for untethered technology is obvious. Most PDAs and 70 per cent of wireless phones are already Web-enabled and wireless network access is on the rise.

Gartner Group Inc. estimates that this year 5.4 million people routinely will use 802.11-enabled technology to go online via networks that hit 11 megabits a second. By 2004, more than 45 million business laptops will be enabled with wireless connectivity. Not surprisingly, HP, Dell, Toshiba and other leading PC vendors are integrating WLAN capabilities into every new laptop.

Given these findings, it’s not surprising that installers and IT staff are being asked with increasing frequency to manage wireless installations in addition to wired networks. The good news is this means more business for you, the installer.

The even better news is that you are more prepared than you think and vendors and resources are available to help you make the transition. The purpose of this article is to familiarize you with the challenges, products and standards that drive the evolution of this emerging market.

THERE ARE LOTS OF WIRES IN WIRELESS

A big misconception is that wireless networks use fewer wires. The truth is that deploying wireless access points (APs) is a huge wiring challenge. A wireless LAN actually is just like a typical wired segment deployment. Ethernet cable and power lines, if necessary, are installed, the access points are hung, antennas are deployed and the access points are configured, usually remotely through the wired network.

In order to grow your business, it will be important to attain proper training and ongoing education on WLAN fundamentals.

The more you know about WLANs, the better equipped you’ll be to advise your customers. While structured cabling systems offer the most security and provide the best performance, the added convenience and lower cost of WLAN implementations continue to make them a popular extension of wired networks.

And vendors continue to promote new and safer ways to secure WLANs. So there is only one thing left for the installer to do: If you can’t beat ’em, then join ’em.

PARTNERS IN PROGRESS

If you are interested in recommending, selling or installing WLANs, you’ll likely need new training and the right tools to get started.

By standardizing on a single wireless product line, you’ll be able to remove a lot of the confusion surrounding interoperability. You should also familiarize yourself with the complete IEEE 802.11 standard.

Taking classes is your first step. Contact your preferred manufacturers, local sales rep or value-added resellers to learn about available classes in your area. They can also point you in the direction of free white papers and professional certification programs through vendor-neutral organizations like BICSI (www.bicsi.org) and Planet3 Wireless www.cwnp.com

Standards drive the wireless world in the same way the ever-changing UTP and fiber requirements drive the way you install and test wired networks today. In a nutshell, 802.11 refers to a family of specifications which specify an over-the-air interface between a wireless client and a base station or between two wireless clients.

While 802.11b is the most widely used standard today, improvements in the transmission and security capabilities have led to the creation of 802.11a.

Unfortunately, 802.11a devices are not backward compatible with 802.11b, which may lead to their demise. 802.11g offers comparable speeds to 802.11a while operating in the same spectrum as 802.11b.

WHERE TO BEGIN

For the network owner, security is perhaps the most important activity in maintaining WLANs. You may also choose to become astute on the topic, but that would take more pages than available in this magazine. For the installer, a site survey is probably the most important step in implementing a wireless network.

During this process you determine where and how to mount WLAN access points. This requires new test tools that test signal strength and detect rogue or neighbor access points that will inhibit your installations.

A site survey is the only way to truly know the wireless design requirements. Without it, a WLAN may never work properly or could cost thousands of added dollars to repair.

SITE SURVEYS MADE SIMPLE

Step one of a site survey requires a physical plan design that shows likely connection areas (i.e. cafeteria, conference rooms) and radio wave obstacles (i.e. walls, elevators). This information will help identify good places for APs, see diagram above.

You also want to find or make a wired cabling map and indicate where network resources and power sources are located. In the chance that power outlets are not readily available, you might opt for Power over Ethernet (PoE) to power your access points via Cat 5e.

Step two is a rogue walk through to locate any unknown or neighbor APs. Due to the ease and affordability of today’s wireless solutions, many unassuming employees are buying a wireless NIC and access point and setting up their own “rogue” WLAN. You can remove rogues, but you will have to work around your neighbors so be sure and document their position.

The first thing you need is a test tool able to track down the access point, locate it and disconnect it from the network. Wireless analyzers have several features designed specifically for this activity. Second, establish a policy against bringing rogue equipment into the office and establishing a routine monitoring process to ensure the policy is being followed.

Monitoring for rogue access points and clients becomes extremely important once you’ve deployed your network. The reason is because most fancy security systems may not stop rogue access point traffic from passing through a network.

And the other problem is that access point, even if its traffic is blocked, is still broadcasting on a channel that you may have assigned to one of the enterprise access points, causing channel interference. So, the rogue equipment monitoring must continue after the corporate wireless LAN is deployed.

The next step is a client walk through. At this stage, a test tool is a must have:

1. Place a test AP at first potential location.

2. Connect to AP as client, using a WLAN tester or laptop.

3. Find where connection drops from 11-> 5.5 Mbps.

4. Mark on map.

5. Test for transmit errors.

6. Mark if errors are above 10 per cent.

7. Repeat steps three to six twice more for three marks per AP.

8. Repeat 1-7 for all potential locations.

These radio frequency (RF) results should validate your initial physical design. If so, you are ready to finalize your design.

1. Find AP combinations that give required coverage.

2. Calculate cabling costs to wire those APs.

3. Choose design with the lowest cabling and equipment costs.

4. Make channel assignments, taking into account neighbor channels to avoid overlap.

Now is where you can weigh cabling costs against wireless equipment costs. With the hardest work behind you, you can feel confident about making recommendations to your customers.

TROUBLESHOOTING REMAINS

Just like in a wired network, the wireless network client issues must be fixed when issues arise. Troubleshooting begins by isolating the problem to either the client or the network. If it is the client, the next task to is to isolate it to the software configuration or to a faulty radio card. With the right wireless troubleshooting tool, you can identify the current software configuration of the client in question, as well as to test the radio hardware for defects.

If the problem is in the network, the IT group will likely take over. Using wireless protocol analyzers, network engineers can analyze the 802.11 packets and see which step the process is failing and can focus on either the authentication process or on likely radio interference issues.

So, troubleshooting wireless looks very much like regular wired t
roubleshooting, with the added complexity of an additional security mechanism and the possibility of radio interference causing problems. Luckily, new tools can help users to both isolate the problem to a local area and in some cases to even identify the solution.

The demand for wireless connectivity is driven by the desire to make the most of one’s time in and out of the office place. Because greater efficiencies pay their own way, this demand will be satisfied. Along the way, it’s up to network installers and IT management to learn yet another way of doing things.CS

Brad Masterson is Canadian Product Manager for Fluke Networks. He has been involved in the field of networking and network testing since 1995. Masterson is a Certified Engineering Technologist registered with OACETT and is a member of BICSI.