A simple home network

Call me an old white-bearded geek but I continue to run a small cluster of servers at home - one main (Win2k3) server that provides LAN services and storage, another that acts as the mail and web development server here, another that runs Asterisk for the phone system, another NAS box that all the PCs here back up to. That's four if you're counting - all sitting in a nice rack powered by a big UPS.

Then there are the workstations: my lovingly crafted, SILENT workstation here in the study, the two in the recording studio, the laptops, the Sony VAIO Media Centre in the lounge (subject of another post before too long, I'm sure) the IPAQ pocket PC ... the media players ...

Networking this little lot is a bit of a problem as I'm currently (for a few more weeks at least) in a rented house so can't drill holes to run network cables between house and garage or between floors. I'm also stuck with the location where the phone line - and hence the broadband ADSL - comes into the building, in my study.

So the servers that talk to each other on their gigabit-LAN connect to the rest of the machines via a mains-borne network that is advertised to run at 85Mbps but actually runs at around 25Mbps on a good day. This mains-borne segment also has to carry the Internet traffic to and from the servers - including the phone traffic to the Asterisk box. The study has its own mini gigabit-LAN for the firewall, my main workstation, printers, the various IP phone devices etc. Finally, there's a WiFI segment driven off a Linksys WRT54GS with upgraded, open source firmware with a repeater to help cover the upper floor - that provides connection to the laptops and the machines in the music recording room upstairs.

Arriving at this mixed-bag approach to the network here took quite a while. The big problem is the connection between the house and garage. For practical reasons (noise, space) the server rack has to sit in the attached garage and there's no way to run a network cable between the two without causing problems with the landlord. My initial attempt used wireless links with a router in the house transmitting through the wall to the garage. Signal quality was appalling, however - maybe the wall has been lined with metal mesh or similar as the link was repeatedly dropped.

I went through several expensive antennae supposed to boost the signal along with equally expensive extension cables to locate the antennae as close to each other as possible with just that wall separating them - all to no avail. The link would still occasionally drop for no apparent reason.

Dropped links are not a good thing on the most critical segment of your network.

I stumbled across mains-borne networking while trawling the 'net looking for a solution to this problem. The units I bought came from Solwise (http://www.solwise.co.uk/net-powerline.htm) who have proved to be a nice company to deal with - one I'd heartily recommend - they quickly replaced one of the (now four) units I've bought from them when it stopped working.

So, are power line devices the networking panacea for the cable-free home or office?

Not quite. Apart from the hardware reliability (my one failed device might be an exception but the build quality of the plug-top units isn't that impressive) it's almost impossible to predict the actual throughput that can be achieved. In my case, I now have one of the units in the study that acts as the master and three slaves. I'll list them and their data rates as reported from the master unit:

• Garage - server farm - 27Mbps
• Lounge - media centre - 9Mbps
• Kitchen - WiFi router - 53Mbps
  

Note that none of the links is achieving the claimed 85Mbps transfer rate - the best rate is to the kitchen only about 20 feet of mains wiring away, while the garage (that sits on another mains ring the other side of the distribution panel) just manages half that - and less than a third of the claimed rate.

The stand-out oddity in the list is the lounge. As far as I can tell, this is on the same mains ring as the master but suffers interference from one of the PSUs that power some of the boxes surrounding the media centre or something else I haven't yet been able to track down.

It's interesting to note that even when plugged side-by-side, these units only manage about 60Mbps. I'd need to research the technology better to be certain about this but it seems to work on similar mechanisms to WiFi - only using the mains cable as its medium rather than radio waves. Of course, the carrier frequencies needed to carry network traffic at these rates has to be very high (in the GHz range, I suspect) so the mains wiring is surely acting as a very large radiator of UHF interference to the neighbourhood and, it would appear from the poor performance of the unit in the lounge here, the coupling of the power-line unit to the mains wiring is pretty critical.

Conclusions - if there are any from this?

• surprise, surprise - WiFi doesn't travel well through walls
  
• mains-borne networking can be a life saver - my garage link has proven reliable apart from the one hardware failure
• neither of these technologies replace a good old copper network cable

Solwise have been advertising a powerline device that's claimed to provide 200Mbps over mains cabling. Initially listed for release this summer, their web site now promises delivery some time in October. Had these devices been available earlier I would certainly have tried at least one pair on the garage link but as I'm hoping to move out of this rented place before too long, the £150 cost will go a long way toward a drum of CAT-6 cable and some fascia outlets.