Wireless is slow, not anymore

Update (Read Me First) 06/21/09 03:01:40 PM

Today I just had to revisit this issue. I thought there must be more to this than I am seeing. I decided to start all over again with the install and configuration of the new router.

I followed some great instructions on how to set the MTU correctly and then made sure that the MTU value (in bytes) were the same on the router as on each computer. I then configured my ISP details in the router. I found that the PPPo* (my ISP operates on PPPoE) setting was incorrectly set last time to PPPoA. Also I have a static IP address from my ISP, I added that explicitly (rather than the standard DHCP choice) and also added the DNS servers explicitly so it would not have to obtain those from the ISP.

I have read in a few places online that there are popular wireless channels that can be prone to interference (for example when using 802.11 b and g, channel 11 is normally not a good choice) due to other household devices operating nearby. After setting the Wireless speed to the maximum setting (270Mbps) 802.11n (on channel 2) I rebooted everything and ran the tests again.

External ping

External Download

Internal ping

Internal Download

Test computers theoretical link speed

Wireless 802.11n

65ms

1.3Mbps

Min 1.26ms Max 2.77ms 0% packet loss

5.5 Mbps and very stable

130 Mbps

Tried uploading a file from my mac to another server on the network and was pleasantly surprised with the following result of approx 8Mbps

CentOS-5.1-i386-bin-DVD.iso                     8.5MB/s   07:12 ETA

Background (Original Post) 06/20/09

I recently upgraded my wireless router as the old one bit the dust. I was quite excited when I read the specs on the anonymous router. This particular router is 802.11 b g and n certified. This unit has wireless speed options of up to 270Mbps in the configuration settings. As I understand it 802.11n only has a constant throughput of 144 Mbit/s meaning that 144Mbps is about as fast as it can successfully deliver packets with a zero error rate. The maximum useful bit rate (note I say maximum not continuous) of 802.11n is 600Mbps. Theory aside I put this to work to see what I could get.

Tests

Note: External is going to test servers such as speedtest.net and internal is purely between the test computer and a server inside my home network.

External ping

External Download

Internal ping

Internal Download

Test computers theoretical link speed

Wireless 802.11n

303ms

0.5Mbps

Min 11.76ms Max 425.58ms 20% packet loss

1Mbps and very unstable

130 Mbps

Wired 10/100

61ms

1.3Mbps

Min 00.69 Max 00.91 0% packet loss

12Mbps and very stable

100Mbps

Ok so at this point I am really scratching my head as the wireless results are not quite what I expected. I understand that there is a difference between maximum flash in the pan readings and constant readings with load. However the gap between 144Mbps and 1Mbps is a bit much.

Finding a solution

First of all I tried moving the router to new positions. Pretty much the same results. Then I had a thought that perhaps trying to use the highest speed may result in a large amount of packets being sent at the cost of efficiency (high error rate). After all I was only getting 1Mbps so setting the router to a max theoretical speed of 54Mbps is not such a silly idea. After reducing all of the values I could find to their minimum I got quite a decent result.

External ping

External Download

Internal ping

Internal Download

Test computers theoretical link speed

Wireless 802.11b g

65ms

1.3Mbps

Min 1.26 ms Max 2.44ms 0% packet loss

Between 3 and 5 Mbps and very stable

54 Mbps

Conclusion

So in the end I guess it is unrealistic to expect ridiculously high throughput as per the advertising on the box. In my opinion it is better to run some tests and see what you are actually getting. Have a play with the settings and sometimes asking for less gives you more.

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