Data Transfer Rate for 54Mbps 3com link
Nho Whei
only 1.67MB per second.
Seems a bit on the low side?
What sort of speeds are deemed acceptable by the cognoscenti around
these parts?
AZApoker
-------------------------------------------------------------------------------------------------------------------------
POKER ACTION AT WWW.AZAPOKER.COM
Bob Willard
1.67 MB/s (~13 Mb/s) on a 54 Mb/s link is pretty decent if the data source
and the data sink are both on the same 802.11G segment.
If you meant 1.67 Mb/s, then something is wrong.
--
Cheers, Bob
Nho Whei
On the face of it Bob, ~13Mb/s doesn't stack up too well against
54Mb/s though does it, or am I missing something too?
Jeff Liebermann
You're missing something.
Under ideal conditions, a 54Mbit/sec wireless connection will give a
maximum of about 25Mbits/sec thruput. See the FAQ:
http://wireless.wikia.com/wiki/Wi-Fi#Performance_and_Speed
for a table of speeds. If you have the 802.11b compatibility mode
enabled, your maximum speed will be about 14Mbits/sec, which is
apparently what you're getting.
If you're going to run benchmarks, I suggest you supply some clue as
to what hardware you're using and how you're testing. To get
25Mbits/sec thruput, you need to be fairly close as the wireless
connection speed will automagically decrease with increased range. The
test should be performed between a wired computer acting as a server,
the access point or router, and the wireless connection. If you try
it wireless to wireless, you will again get half the speed or perhaps
12Mbits/sec max. I suggest using Iperf 1.7:
http://www.noc.ucf.edu/Tools/Iperf/default.htm
--
Jeff Liebermann je...@comix.santa-cruz.ca.us
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
do...@xrexxdatax.usenet.us.com
> Under ideal conditions, a 54Mbit/sec wireless connection will give a
> maximum of about 25Mbits/sec thruput. See the FAQ:
> http://wireless.wikia.com/wiki/Wi-Fi#Performance_and_Speed
> for a table of speeds. If you have the 802.11b compatibility mode
> enabled, your maximum speed will be about 14Mbits/sec, which is
> apparently what you're getting.
Do you mean "802.11b compatibility mode enabled", or in use?
I see iperf speed of 26.4 Mbits/sec between 54g and a wired desktop, and my
WAP is capable of communicating with 802.11b, although none are connected
right now. iperf duplex shows 13.1 + 14.6 Mbits/sec
I can write to a Windows share at 2461 KBytes/Second.
Maybe our 14Mbits/sec poster has some 802.11b devices connected to his WAP.
--
---
Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5
Jeff Liebermann
Connected, but no traffic. See:
| http://www.atheros.com/pt/whitepapers/Methodology_Testing_WLAN_Chariot.pdf#search=%22802.11b%20compatibility%20mode%22
Since the key feature of 802.11g is backward compatibility
with 802.11b, throughput tests should be done with an 802.11b
client device connected to the access point but otherwise
idle. This setup ensures that the 802.11g network is operating
in an 802.11b compatible mode.
When I tried it with a Broadcom based WRT54G, it didn't quite work
that way.
If the 802.11b compatibility mode is enabled, the access point spends
a small amount of time listening for 802.11b traffic. It apparently
(from my testing) can can be *ANY* 802.11b traffic and does not need
to be the same SSID. When it hears even one 802.11b packet, it
enlarges the sampling time so that it can properly decode the 802.11b
packets. I think (not sure) that the time slicing is about 2/3
802.11g and 1/3 802.11b.
I ran the usual IPerf tests on my WRT54G v1.1 and got something near
the expected 25Mbits/sec with 802.11b compatibility turned off. When
I turned it on, the speed slowed down to about 22Mbit/sec. I then
fired up my Orinoco Silver card on another laptop and connected to the
WRT54G. Thruput dropped to about 13Mbits/sec. Note that there was no
real 802.11b traffic, just a connection. When I dropped the
connection, the speed improved dramatically after about 15-30 seconds.
I must admit that I did a really sloppy job of traffic measurement and
that the numbers are from my foggy memory. I'll do it again when my
WRT54G returns from a site survey.
do...@xrexxdatax.usenet.us.com
> Connected, but no traffic. See:
> I ran the usual IPerf tests on my WRT54G v1.1 and got something near
> the expected 25Mbits/sec with 802.11b compatibility turned off. When
> I turned it on, the speed slowed down to about 22Mbit/sec. I then
> fired up my Orinoco Silver card on another laptop and connected to the
> WRT54G. Thruput dropped to about 13Mbits/sec. Note that there was no
> real 802.11b traffic, just a connection. When I dropped the
> connection, the speed improved dramatically after about 15-30 seconds.
I see 26M with my Netgear WRG614 set for 802.11b compatibility, and no
802.11b clients connected.
I haven't tested with the compatibility mode turned off.
I plugged in an 802.11b USB dongle, whcih connected. No traffic on
802.11b. My rate dropped to 16MBits/Sec.
So, it's okay to have the compatibility mode turned on for backwards
compatibility, but actually having the 802.11b clients connected will slow
down the 54g devices, with performance returning when the b device goes
away.
John Navas
wrote in <ecnhs3$qh9$1...@blue.rahul.net>:
>Jeff Liebermann <je...@comix.santa-cruz.ca.us> wrote:
>
>> Connected, but no traffic. See:
>
>> I ran the usual IPerf tests on my WRT54G v1.1 and got something near
>> the expected 25Mbits/sec with 802.11b compatibility turned off. When
>> I turned it on, the speed slowed down to about 22Mbit/sec. I then
>> fired up my Orinoco Silver card on another laptop and connected to the
>> WRT54G. Thruput dropped to about 13Mbits/sec. Note that there was no
>> real 802.11b traffic, just a connection. When I dropped the
>> connection, the speed improved dramatically after about 15-30 seconds.
>
>I see 26M with my Netgear WRG614 set for 802.11b compatibility, and no
>802.11b clients connected.
>
>I haven't tested with the compatibility mode turned off.
>
>I plugged in an 802.11b USB dongle, whcih connected. No traffic on
>802.11b. My rate dropped to 16MBits/Sec.
How about with it plugged in but not connected?
>So, it's okay to have the compatibility mode turned on for backwards
>compatibility, but actually having the 802.11b clients connected will slow
>down the 54g devices, with performance returning when the b device goes
>away.
You haven't presented enough evidence for that conclusion.
--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_HowTo>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>
Nho Whei
Mark McIntyre
Whei <No...@hotmail.com> wrote:
>I've just measure it & find I'm getting an effective transfer rate of
>only 1.67MB per second.
>Seems a bit on the low side?
A bit, but not much.
54Mbps is roughly 6MB/s
At best you will get ~50% throughput due to protocol overheads, half
duplex etc etc -> 3MB/s.
Transferring small files will further reduce this due to further
overheads.
etc etc
It also depends on the hardware at each end. My server has a 100Mbps
ethernet card but struggles to push out more than 10Mbps with anything
requiring the CPU to intervene, as its running on a 200Mhz Pentium
Pro.....
--
Mark McIntyre