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802.11b Wireless Networking (Part 4)

I needed to connect one more PC to my wireless LAN and this proved slightly more difficult than the others because it would not accept the D-Link PCI card and it also lacked USB ports.

Fortunately, it did have a 10/100 ethernet port. As I'd been so impressed with the NetGear router, I decided to opt for their ME101 wireless bridge. So the final setup is as follows :-

Netgear DG824M Wireless Router/Modem

D-Link AirPlus DWL-520+ Wireless PCI Adapter
Orinoco Silver PCMCIA Card
Belkin 802.11b Wireless USB Network Adaptor
Belkin F5D6020 PCMCIA card Netgear ME101 Wireless Ethernet Bridge
1.6GHz PC
Psion netBook
233MHz Pentium PC
P90 Laptop
200MHz Pentium PC (10/100 LAN, no USB)

At first I found the distinction between 'wireless adapter' and 'wireless bridge' confusing but it is less so once you actually use both components; basically the wireless bridge is virtually transparent to the client that connects through it.

Once the bridge is configured with the appropriate wireless settings, it can be used by any 10/100-equipped computer just by plugging it in whereas the 'adapters' require wireless drivers to be installed on the computer itself.

The ME101 was also attractive because it claimed to have higher signal strength than most adapters and this was particularly useful because the client PC was located diagonally through three walls and a ceiling - the weakest signal location in my house. Obtaining a 40-50% signal was easy and the PC was connected to the internet in no time.

Unfortunately, this relatively strong signal made troubleshooting another problem very difficult indeed...

For days - I struggled to get Windows' 'File & Printer Sharing' to work reliably; tinkering with network card settings, reading various resources on the internet, trying new drivers etc. but it just didn't want to play.

All through this process I never questioned the signal strength because the 40-50% was double what I typically achieved on my sons' PCs, and they can share resources easily enough. The excellent speed on the internet also appeared to imply that this was sufficient.

However, the ping response between this PC and the others was erratic. Eventually I went back to basics and added a longer patch cable so that I could position the bridge for an even higher signal strength. With a bit of experimentation I discovered that I needed to achieve >=60% in order to get reliable file & printer sharing (!)

It wasn't hard to find a location in the room that achieved a consistent 70% signal and this solved the problem. For me this has highlighted a fundamental difference between wireless adapters and bridges:-

A PC attached to a bridge via 10/100 ethernet cable is intolerant of lost packets, so the bridge must be positioned for as strong a signal as possible if file & printer sharing is required - the wired ethernet card is just not expecting any packet loss.

Internet connections are inherently 'lossy' to start off with so the handling processes are much more robust and signal strength isn't such an issue.

Speedwise, the 200MHz PC connected to the bridge has one of the fastest connections to my main PC. For some people, 802.11b isn't fast enough, but if I can achieve a reliable 1.5Mbps then I am quite happy(*). This is still three times faster than my broadband connection - sufficient for occasional file sharing, and more than adequate for printer sharing and internet use.

* The D-Link PCI card has an excellent throughput display but I also use the 'GoodTime.MPG' file from the Windows 98 CDROM as a practical benchmark. If I can stream this video from the hard disk on one PC to Media Player on another, then I know that the setup is optimised.

part 1 | part 2 | part 3 | part 4

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Sunday, 15 February 2004