How SLOW is your Airport to Airport speed?

**ddma** · January 23rd, 2002, 10:42 AM

This is a problem I have got since I bought my Airport last year... I just made a simple test, copying a 11.5MB movie file from my iBook 600 (Mac OS X 10.1.2, IBM 4,200rpm 2MB Buffer Hard disk, 256MB) to my iMac 400 (Mac OS X 10.1.2, IBM 7,200rpm 2MB Buffer Hard disk, 512MB). The result was 1 min 20 sec... It was so slow even less than 2Mbit/sec... But just wonder Airport shoudl be said to be 11Mbit/s...

Anyone have any idea?

Thanks.

**roger** · January 23rd, 2002, 02:53 PM

The bandwidth does not relate to the amount of data that will be transmitted directly. Protocols such as TCP/IP and Appletalk wrap the data with headers and trailers to ensure that the data is transmitted in the right order and that packets are re-sent if they are malformed, lost, etc. Appletalk is a particlularly slow protocol, but is fairly resilient one. TCP/IP again is not the speediest or most lightweight of protocols, but does give resilience. Other protocols are faster and more lightweight, but usually at a cost of lost packets, etc.

Just look at 56k modems - you don't get 56k through that medium, so you can't really expect 11MB through airport. You won't get 10MB/100MB through a hardwire ethernet connection either.

Roger.

**ddma** · January 23rd, 2002, 07:36 PM

Thank you guyz. I know such interference things. When I was testing my systems, I put all the Airport Base Station, iMac, iBook closed together on a table. And the signal strength is d@mn full. I know it will loss some data via TCP/IP or AppleTalk, and it won't take up the full 11Mbit bandwidth especially it is wireless networking. But the question is, why am I using 10MBit Ethernet Cable Network can reach the max. speed at 8-9MBit (9xxk - 10xxk/s, sometime 12xxk/s) but the Airport only up to 1Mbit - 2Mbit (2xxk/s)?

And also, have you tried a simular test and what are you guys speed?

P.S. In Mac 2 Mac wireless networking, The APBS doesn't help a lot, right? Btw, I have upgraded it to the latest Apple firmware (3.83).

Thank you again!

**ddma** · January 23rd, 2002, 07:56 PM

Hey - I just ran another test! This time, I used my iMac to create a Computer to Computer Network. And I tried to copy the same file from my iBook to my iMac and the result was 29 sec... How comes?????????? WTF to my APBS?

FYI. The other computer never shown up in the "Go > Connect to Server". I don't know any of my setting is set wrong!! I always have to type the full IP address whenever I wanna connect the other Mac.

In my case, I always use 100Base-T Ethernet to attach my 2 Macs for file sharing and Airport for the Interent. I just set both in the Network Preference "Using the DHCP".

Also, I have maken AppleTalk active on the "Built-in Ethernet" on both machines becasue sometime I will switch to OS 9 for work. And my iBook need to connect to my company OS 9 File Server as well.

Thanks for helping.

**.dev.lqd** · January 26th, 2002, 02:36 PM

I imagine that the FTP values you got were due to software or hardware problems on either the client or the server. I have been able to use the built in ftp client on windows 2000 to push a sustained 10 megabytes each second from my OSX machine back when I started using 10.0

The gigabit ethernet adapter that comes built into powermacs since the dual 500 days (which mine is) is -really- good, although I can't vouch for the NIC's of mac's past.

The network adapter, TCP/IP stack, memory subsystems, memory management, scheduling system, multitasking system, etc. etc. etc. all play important roles in network performance. While the protocol can be a detriment to the transfer rate- even worse is the software implementation of the protocol. I'd like to think that ill-utilized hardware is more prevalent that ill-made hardware... but that might be the idealist in me.

There are some wretched FTP clients out there- and even more wretched FTP servers- which function well enough under typical conditions but choke under heavy load.

**JohnnyV** · January 26th, 2002, 11:25 PM

I get about half a meg/sec max on my Airport. I have a powerbook connecting to an iMac (acting as a software basestation) the iMac is running OS 9, all have the lastest software updates and firmware updates

**ddma** · January 26th, 2002, 11:45 PM

Yes, the computing to computing network is faster than there is an Airport BS in betwee... Don't know why.

**roger** · January 28th, 2002, 03:05 AM

It may be that your hardwire connection has some compression built in. If it has then the speed that you are seeing will depend on the nature of the data that you are sending:

For example, I used to work for a company that ran lines out to our clients. We had more control over our lease lines and could compress the data over them compared to ISDN. For this reason, even when copying compressed data a 64k lease line showed the same performance as a 128k dual ISDN (about 1MB Min). If I created a massive file just full of spaces, the speed would still be 1MB/min over ISDN, but it would be sent in very little time over the compressed 64k lease line. This is a similar concept to zipping - the compression rate that you get depends on what is in the file. (a 1.7MB file full of spaces compresses down to 9k). Compression methods vary a lot as well.

The speed reduction could be that the protocol that airport uses to send information is fairly hefty and takes up a lot of space as well. This is likely due to the protocol developers knowing that interference will take place. They will need to have a lot of parity checks to ensure that the data is well formed and this parity information needs to be sent, reducing the 'apparent' speed of the data transfer. With a hardwire ethernet connection the protocols can assume less attenuation and so can speed up the data transfer speed by wrapping the data in less 'cotton-wool'. When sending data over airport your data will be wrapped within several protocols.

Hope that this helps a little.

Roger.