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Paul Alvarez · Jul 15, 2008, 06:57 PM

I have 4 different Airport units purchased over the years and wanted to confirm whether I am sub-optimizing my network performance due to my set up. I have an Airport Extreme (n) as my main unit connected to the cable modem. Since this is in the back of the house, I need to extend the network by using two Airport Express (both g) and an older Airport Extreme (g). I get good coverage through the whole house but I have two questions:

1. I have heard that using multiple base stations degrades performance by half for each unit in the chain. Is this true?

2. If I converted the two Express units and the older Airport Extreme to n versions, would this improve performance when using them to extend the network or would the multiple base station issue (see above) degrade performance anyway?

I just upgraded my cable ISP performance to the highest possible level (16Mbps download). By doing a speedtest, I get around 8Mbps from the wireless network. One computer that is hard wired does get this level of performance. I just wanted to see if I can improve the wireless performance to something closer to hard wired.

All input appreciated.

Paul

mduell · Jul 15, 2008, 11:31 PM

I don't know about half for each, but using wireless extenders degrades performance the same way more clients degrades performance (until you get to >3 wireless extenders in the same area and have to go to nonoverlapping channels, and then it gets real ugly). As Eug (a forum regular) discovered in another thread, networks with multiple extenders can be a hassle and generally unstable.

If you're running g or n you get the same proportional degredation; with n you just have more bandwidth to start with.

I'd buy one good non-Apple n base station and a big omni antenna. Linksys new dual radio one is pretty good, because you can run both g and n networks at full performance from one box, but I don't recall if it supports external antennas.

Simon · Jul 16, 2008, 03:27 AM

Originally Posted by Paul Alvarez

1. I have heard that using multiple base stations degrades performance by half for each unit in the chain. Is this true?

Yes. Bandwidth for a specific client scales roughly like (1/2)^n where n is the number of relays between that client and the main station.

2. If I converted the two Express units and the older Airport Extreme to n versions, would this improve performance when using them to extend the network or would the multiple base station issue (see above) degrade performance anyway?

Multiple repeaters degrade performance as detailed above. However n offers better range and better bandwidth so you will see better performance form n equipment. In terms of performance the best thing to do is run n clients off an n base station and run older clients (with g or even b) on a separate network. The b/g network can still be part of the same subnet (for example if you hook up a second base station in bridge mode to the main stations LAN port).

I just upgraded my cable ISP performance to the highest possible level (16Mbps download). By doing a speedtest, I get around 8Mbps from the wireless network. One computer that is hard wired does get this level of performance. I just wanted to see if I can improve the wireless performance to something closer to hard wired.

As long as your wireless clients get the same performance as when you hook up one of them directly to your cable modem you're fine for WAN traffic. If this is no longer the case you should consider updating network hardware. OTOH if you're also interested in LAN performance (for example streaming video over your wireless network) you should consider updating wireless hardware regardless of your WAN performance.

Paul Alvarez · Jul 16, 2008, 04:22 PM

Thanks for the input. I am going to minimally try adding one new Airport Express n to the main station and take the others offline to see how performance is affected. I may lose some coverage through the whole house but hope that with the improved range of the Express n, and only one as a relay, it will speed up my network and cover more area.

mduell · Jul 16, 2008, 08:26 PM

Originally Posted by Simon

Yes. Bandwidth for a specific client scales roughly like (1/2)^n where n is the number of relays between that client and the main station.

Good point; I was thinking of the APs in a star, not in a line.

Simon · Jul 17, 2008, 01:47 AM

Which is also the reason a star configuration gives you much better bandwidth with the same number of relay stations. But usually people don't have the choice. If your client is more than twice the range of a base station away you have to go line with 802.11.

Paul Alvarez · Jul 17, 2008, 02:07 PM

I checked my base stations in the chain after the main one and found that I had set them all up as relay. Based on input here, I took one off line and changed one Express to just join the network so I can use AirTunes. The other Express I left set up as a Relay station to get better coverage. Just doing this improved network performance quite a bit. In the prior set up a speed test would come in at around 9Mbps consistently (again, I am paying Comcast for 16Mbps).

After changing the set up, I now consistently get between 11 and 12 Mbps. I am going to swap out the one Express on Relay with a new one which upgrades from g to n. Hopefully, this will add a bit more bandwidth.

Thanks for the inputs here. It has helped.