Mar 21 2008
The home network
It’s been a while since I wrote about networking here. So let’s look at domestic networking setups.
The scenario we have in our flat is quite ordinary. There are two computers on the network, one desktop machine and one laptop. Traditionally these two would be connected to a switch so they can communicate with each other. In big companies or other places with extensive networks then a switch is necessary to juggle all the traffic in a reasonable way.
(The diagram here shows three computers connected to a switch, the box with the extended X shape in it. The computers can send packets to each other through the switch.)
But for small networks a full-blown switch is pretty useless. It’s like having a private telephone exchange in a house with only two telephones. So most people won’t see a separate switch: it will be integrated in the box with other things.
One thing you’ll notice in the diagram shown is that there’s no external communication. There’s no internet access — the machines can only talk with others on the same network. The connection between the home network and the rest of the internet is done with a router. It directs the network traffic like a traffic policemen. Local stuff stays local, but data that needs to be sent elsewhere goes via the router.
This is what a network with external access looks like:
You can see that here the router is doing very little as well. There’s only one connection in and one connection out. So in my house, and probably in yours, the router and the switch are combined into one box. It does switching and routing (and often wireless access too). My home network looks like this:
(Apologies for the lame diagrams. Anyone know pretty diagram software for Linux? Pastel shades and smooth gradients welcome.)
Inside the router/switch hybrid beast the software analyses the destination for each packet sent and decides whether the destination is on the local network or somewhere else, and then sends it in different directions accordingly.
Apart from this, it can probably also hand out IP addresses to new machines as they join (extremely useful, so you don’t have to do any manual configuration). There may be some firewall capability too, so that particular programs can be prevented from sending signals in or out. It’s quite amazing what features are available in 50 quid devices!
If you’re thinking of buying an access point might I suggest you /consider/ the Airport Extreme? AFAIK Helen has a Mac, and the Airport Extreme allows you to connect a USB disk to it, and access it over the network / Time machine backup to it.
We already have an unused Airport Express, so if we need wireless extension I’d rather make further use of that.
I have an Express left over from uni. However in the flat use a standard Netgear wireless box that we got for free. My dad bought it for his work, ages ago, using work approved suppliers, going through all the right channels, having the purchase approved by the relevant authorities and then about a month after he bought it said relevant authorities went ‘Hang on OMGS you can’t use wireless in the Surgery when there’s patient data involved’ (I KNOW) and his attitude was ‘well fuck’em’ and he gave it to us. For free. Technically it still belongs to the NHS but they won’t allow him to use it.
Our current flat is wee enough overall that there’s no need for the Airport Express to boost the signal, we get ample throughout. My parents have an Airport Extreme (it replaced our vintage first editon Airport)(the modem in it died, but in third year of uni I used it as a wireless connection to our non-wireless router, which was cool…until I fried it by connecting a powersupply with mis-connected polarity to it…boo). However in my maw and Paw’s house, which has big solid stone walls, one airport extreme along won’t hack it. They have an additonal signal booster and also two airport expresses (one of which is connected to our pan-house stereo….iTunes in any room!!)