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You are here: MacNN Forums > Enthusiast Zone > Networking > Need a baseline of N transfer speeds

Need a baseline of N transfer speeds
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milhous
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Nov 12, 2011, 08:17 AM
 
Have an Airport Express N connecting an Air and a Mini all running N. I think the file transfers are really slow. Would appreciate it if someone could give me a real-world baseline for copying a file from machine to machine and estimate how much time it takes. Please include the time and size of file. Thanks.
F = ma
     
Spheric Harlot
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Nov 12, 2011, 08:35 AM
 
What throughput are you getting?
     
milhous  (op)
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Nov 12, 2011, 04:31 PM
 
made a 100MB file using:

mkfile 100m 100MB


which turns out to be 104.9MB.

From Air to Mini: ~ 43 seconds.
From Mini to Air: 1m53seconds!

Considering reinstall of Lion on the Mini. Wifi seems flakey, and I get disconnects when screen sharing and streaming music.
F = ma
     
mduell
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Nov 12, 2011, 06:33 PM
 
(100 MB) / (43 seconds) = 18.6 Mbps

Even your "fast" result sounds like you're on 802.11g (54Mbps), not n.

On my crummy n connection I'm getting about 50Mbps even with ssh overhead:
100% 24MB 6.0MB/s 00:04
     
Spheric Harlot
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Nov 12, 2011, 06:38 PM
 
Do you have an iPhone 3G/S or an iPod touch?

The second any non-n-capable device hooks up to the wireless network, transfer speeds go to the basement.

The big problem with WLAN is that the slowest device determines the entire network's speed. Which is why the Airport Extreme and Time Capsule (but not Express) offer two simultaneous networks—one exclusively n, and one for b/g speeds.
     
milhous  (op)
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Nov 12, 2011, 10:14 PM
 
4 devices are running N 2.4 Ghz, 1 is only G at 54mpbs. Tried changing the Express to go to N 5Ghz, but realized the iPhone 4S doesn't support it, and leaving out the G device.

What's interesting is when I ping from Air -> Airport Express, pings come in for the most part at sub-10ms times. Similarly for Mini -> Airport Express.

When pinging from Air -> Mini, I get sub-1000ms times and can feel it when screen sharing stutters, or iTunes streaming starts to stutter. All running Lion and up-to-date.

I'm reinstalling Lion on the Mini because I may have fouled up things when manually migrating stuff over. Also going to borrow my friend's Thinkpad as a 3rd machine to see if I can narrow down which machine it is, but am betting it's the Mini.

Everything's running 10.7.2 and up-to-date. All devices are within a few feet of the Airport Express. The AE firmware is also current as of this week.
F = ma
     
Spheric Harlot
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Nov 13, 2011, 04:23 AM
 
Well, the G device explains the general speed: you're not actually running an N network.
     
milhous  (op)
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Nov 13, 2011, 04:54 AM
 
True, though Network Utility says the link speed is at 144mbps, even with the G device attached.

Tomorrow, I'll test without the router by creating an ad-hoc network between Air, mini, then add my friend's Thinkpad. That should provide more clarity. The mini now has a clean 10.7.2 install.
F = ma
     
milhous  (op)
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Nov 13, 2011, 07:38 PM
 
Did more testing, and think it's the Airport Express.

I set-up an ad-hoc network between 3 machines with static IP addresses. The pings were nice and consistent, sub-10ms.

I tried the advice from this post:
osx - MacBook Pro Encountering High Latency - Apple - Stack Exchange

and surprisingly it got the times down. The idea is that AE is "sleeping" or going into a constant low power state. So if I kept one machine on the networking pinging at 200ms intervals:

sudo ping -i .2 <default gateway>

Pings to other machines went down to sub-10ms. If I stopped the pings, they would skyrocket.

Also got iStumbler running, and I'll see if switching to a different channel will solve anything. Otherwise, I'll look for another router.
( Last edited by milhous; Nov 13, 2011 at 07:39 PM. Reason: typo)
F = ma
     
Waragainstsleep
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Nov 13, 2011, 08:00 PM
 
I have an MBP and an old MacBook running on a N network from the first generation of the square AP Extremes. There is a G Express on the network too and when I'm using it my iPhone 3GS is G too. Oddly I do seem to get N speeds more often than not. Sometimes it goes incredibly slow and I have to reboot the Extreme.
I have plenty of more important things to do, if only I could bring myself to do them....
     
   
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