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deleonju · Nov 22, 2002, 12:18 PM

If the airport suposedly has a speed of 11 Mbps, then why is it when I'm tranfering files between computers using Airport, I only get 512Kbps max. I'm transfering from a powerbook that's right next to the base station to a powermac that's connected by ethernet.. Maybe this is a stupid question. maybe it is just a matter of kilobits and kilobytes but I'm not quite sure..

thanks,

ghporter · Nov 23, 2002, 08:34 AM

The "11Mbps" is gross data rate-sort of like what your gross salary is, as compared to net. The net data rate depends on the protocol you're using, signals that can interfere with the AirPort's path, ethernet collisions, and of course the basic overhead of the system.

The stated rate is in megabits (Mb). Are you getting 512 megabytes (MB)per second? That's darn good! However, if you're getting only 512 megabits, that's pretty bad. It may come down to what protocol you're using, and whether or not you have everything optomized for that protocol. And even if you're getting a good rate, there can be a few tweaks to look at within your network, the first being to make sure the network card in your PowerMac is set for full duplex at its highest rate (100BaseT, or just 100-it depends on which OS version you have and what NIC you're using).

deleonju · Nov 23, 2002, 12:11 PM

I'm getting 512 K/s. As I understand it, Kbps is kilobytes per second and kbps is kilobits per second. I only get Megabytes per second when transfering files over Ethernet and that's between 5-10 MB/s over 100BT ethernet full duplex.

My question is.. If it's supposed to be 11 Mbps (megabits per second) which is 1.375 MBps (Megabytes per second), then why do I only usualy only get half as much 500-600 K/s? Even transfering from ethernet (100BT full duplex) to airpot or from an ibook to a powerbook connected to each other only through their airport cards and sitting right next to each other..

Originally posted by GHPorter:
The "11Mbps" is gross data rate-sort of like what your gross salary is, as compared to net. The net data rate depends on the protocol you're using, signals that can interfere with the AirPort's path, ethernet collisions, and of course the basic overhead of the system.

The stated rate is in megabits (Mb). Are you getting 512 megabytes (MB)per second? That's darn good! However, if you're getting only 512 megabits, that's pretty bad. It may come down to what protocol you're using, and whether or not you have everything optomized for that protocol. And even if you're getting a good rate, there can be a few tweaks to look at within your network, the first being to make sure the network card in your PowerMac is set for full duplex at its highest rate (100BaseT, or just 100-it depends on which OS version you have and what NIC you're using).

ghporter · Nov 23, 2002, 01:22 PM

Originally posted by deleonju:
My question is.. If it's supposed to be 11 Mbps (megabits per second) which is 1.375 MBps (Megabytes per second), then why do I only usualy only get half as much 500-600 K/s? Even transfering from ethernet (100BT full duplex) to airpot or from an ibook to a powerbook connected to each other only through their airport cards and sitting right next to each other..

I'm assuming that you have everything as optimized as possible. That includes telling both ends of the AirPort connection to run at their highest rate. The 802.11b standard calls for rates of 1, 2, 5, and 11MBps, and most (including Apple) equipment manufacturers provide for an automatic feature that selects the fastest useable rate. Both the base station and the AirPort card have to be set for 11MBps or automatic for you to be able to go that fast.

Now if your question is really "why, when I transfer a 512KB file, does it take a whole second when I should barely notice the transfer," that's the overhead I was talking about. The wireless network tries to simulate an ethernet wired network, plus it has to handle correctly passing the ethernet packets via radio signals. The combination of ethernet overhead and wireless overhead gives you a "useable" throughput that's lower-much lower-than you'd expect.

aaanorton · Nov 24, 2002, 11:10 AM

Try the following:
move BS further away from computer (particularly the monitor)
move it away from a cordless phone (handset and base)
disable any WEP

To be honest, I don't know how Airport s/w works, but if I disable WEP (and filter MAC addresses) on my Asante router, I naturally get faster transfers. Most of the decrease probably lies in the overhead Glenn mentioned, though.

ghporter · Nov 24, 2002, 04:15 PM

Thanks for the vote of confidence, aanorton. In my experience running 128 bit WEP versus none, I haven't been able to detect a difference.

aaanorton · Nov 26, 2002, 12:02 PM

Wow, really? I used to use 128 WEP too, but turned it off 'cause it seemed like file transfers were so slow. Again, I'm on an Asante router/AP. Could that be the diff? Maybe I'll give it another shot...
Of course, if you're simply web surfing, I doubt the slow-down would be noticeable. Do you often transfer large files between computers?

ghporter · Nov 26, 2002, 03:17 PM

My hardware is a Linksys WAP11 access point and a WPC11 PCMCIA card in a PC laptop. I'm not sure, but I would guess that the Linksys equipment handles WEP in hardware, while others use software. Hardware is, of course, the better solution, since there's only so much processing power in one of these inexpensive routers/access points.

MikeD · Feb 9, 2003, 12:43 AM

in my linksys router, I noticed that there are two rate options..

Basic rate and TX rate. What is the difference between these two and how should they be set?

The basic default is 1-2Mbps

TX Rate is at 1-2-5.5-11Mbps

Should I change the basic to = that of the TX rate?

ghporter · Feb 9, 2003, 10:10 AM

Yes, I think you should set everything to be the same, but be careful about it. You should set the thing for the highest rate, but allow for "auto fallback" as well. My WAP11 has check boxes for all allowable rates, and another box for auto fallback, so when I get into some situation that prevents the fastest speed, the equipment will still connect as fast as it can.

thesearcher · 11:22 AM

It's really confusing, but
K = binary kilobytes.
Kbps = binary kilobits per second.
kbps = metric kilobits per second.
Data transfer rates are typically displayed in metric bits per second.