802.11b/cable speed comparison?

How does the transmission by wireless 802.11b compare (under best
conditions) to LAN setup by Ethernet 10/100 cables? How much LAN file
transfer speed (not internet access) do you give up by going to wireless?

--

Jeff McPherson
Email address deliberately false to avoid spam
(E-Mail Removed)
Outgoing mail is certified Virus Free by AVG

In article <XRmJb.39315$A%(E-Mail Removed)>,
Jeff Malka <(E-Mail Removed)> wrote:
:How does the transmission by wireless 802.11b compare (under best
:conditions) to LAN setup by Ethernet 10/100 cables? How much LAN file
:transfer speed (not internet access) do you give up by going to wireless?

It depends a lot on what you are trying to do. Real 802.11b
transfers peak about 6 megabits per second. That's a lot faster
than residential internet service, but for some kinds of traffic
you can tell the difference.

People generally spend well over 90% of their time just looking
at the screen (interpreting what has been sent to them, or
thinking of the right word to write, or hunting and pecking
for the right key to press), so a -lot- of the time, 11g is
just fine. But if you are copying a 100 megabyte file over
the 'net, that difference between 60 megabits per second
real throughput and 6 megabits per second real throughput
is a difference between 15 seconds and 2 1/4 minutes, which
starts to get pretty noticable.
--
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typewriters, and Usenet is NOTHING like Shakespeare. -- Blair Houghton.

On Fri, 02 Jan 2004 23:08:39 GMT, in alt.internet.wireless , "Jeff
Malka" <(E-Mail Removed)> wrote:

>How does the transmission by wireless 802.11b compare (under best
>conditions) to LAN setup by Ethernet 10/100 cables? How much LAN file
>transfer speed (not internet access) do you give up by going to wireless?

10BaseT gives you 10Mb/sec (assuming full duplex)
100BaseT gives you 100Mb/sec (ditto)

11b gives you (at best) ~5.5Mb/sec as its a half-duplex protocol. Less
in practice as the protocol has a fairly high encoding/maintenance
overhead.

My own experience is that for significant data transfers, the wireless
is considerably less than 50% of the speed of 10BaseT, and absurdly
slow compared to my lan's normal 100 full duplex.


Mark McIntyre


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On 2 Jan 2004 23:35:27 GMT, in alt.internet.wireless ,
(E-Mail Removed) (Walter Roberson) wrote:

>In article <XRmJb.39315$A%(E-Mail Removed)>,
>Jeff Malka <(E-Mail Removed)> wrote:
>:How does the transmission by wireless 802.11b compare (under best
>:conditions) to LAN setup by Ethernet 10/100 cables? How much LAN file
>:transfer speed (not internet access) do you give up by going to wireless?
>
>It depends a lot on what you are trying to do. Real 802.11b
>transfers peak about 6 megabits per second. That's a lot faster
>than residential internet service, but for some kinds of traffic
>you can tell the difference.

He did specifically say "not internet access".

>People generally spend well over 90% of their time just looking
>at the screen

True but largely irrelevant for the OP's quesiton about file
transfers... :-)

(the rest of your posting was spot on of course)


Mark McIntyre


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Jeff Malka wrote:

> How does the transmission by wireless 802.11b compare (under best
> conditions) to LAN setup by Ethernet 10/100 cables? How much LAN file
> transfer speed (not internet access) do you give up by going to wireless?
>

It would be somewhat slower than 10 Mb ethernet, and significantly slower
than 100.

--

Fundamentalism is fundamentally wrong.

To reply to this message, replace everything to the left of "@" with
james.knott.

In article <(E-Mail Removed)>,
Mark McIntyre <(E-Mail Removed)> wrote:
> On Fri, 02 Jan 2004 23:08:39 GMT, in alt.internet.wireless , "Jeff
> Malka" <(E-Mail Removed)> wrote:
>
> >How does the transmission by wireless 802.11b compare (under best
> >conditions) to LAN setup by Ethernet 10/100 cables? How much LAN file
> >transfer speed (not internet access) do you give up by going to wireless?
>
> 10BaseT gives you 10Mb/sec (assuming full duplex)
> 100BaseT gives you 100Mb/sec (ditto)

I believe it's actually 20 and 200 respectively. Can anybody confirm or deny?

> 11b gives you (at best) ~5.5Mb/sec as its a half-duplex protocol. Less
> in practice as the protocol has a fairly high encoding/maintenance
> overhead.

When copying a large file using 802.11b through a USR 8054 router, XP shows
56% of an 11Mbps link used. That's 6.2Mbps, or 770 KB/s.

> My own experience is that for significant data transfers, the wireless
> is considerably less than 50% of the speed of 10BaseT, and absurdly
> slow compared to my lan's normal 100 full duplex.

AOL.

--
-eben (E-Mail Removed)m home.tampabay.rr.com/hactar
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You are the Lord of the Dance, no matter what those idiots at
work say. -- Weird Al, _Your Horoscope for Today_

In article <bt5eh1$qd9$(E-Mail Removed)>,
Hactar <(E-Mail Removed)> wrote:
:In article <(E-Mail Removed)>,
:Mark McIntyre <(E-Mail Removed)> wrote:
:> 10BaseT gives you 10Mb/sec (assuming full duplex)
:> 100BaseT gives you 100Mb/sec (ditto)

:I believe it's actually 20 and 200 respectively. Can anybody confirm or deny?

Mark was assuming unidirectional file transfers. He refers to
full duplex because if you are using TCP half duplex then you have to
stop sending for part of the time in order to receive the
acknowledgements, thus making it impossible to transfer at
full wire rate.

If you were doing bidirectional file transfer, you would not be
able to get the full 20 or 200 mbit/s because of the need to send
acknowledgments for the traffic in the other direction.

And of course you cannot achieve full wire rates anyhow because of the
Layer 1, 2, 3, and 4 overheads, preamble, checksum, and intra-packet
gap (IPG).
--
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What will be your last contribution?
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Thank you all. I could notice the difference in large file transfers and
was wondering about it.

--

Jeff McPherson
Email address deliberately false to avoid spam
(E-Mail Removed)
Outgoing mail is certified Virus Free by AVG

"Jeff Malka" <(E-Mail Removed)> wrote in message
news:XRmJb.39315$A%(E-Mail Removed)...
> How does the transmission by wireless 802.11b compare (under best
> conditions) to LAN setup by Ethernet 10/100 cables? How much LAN file
> transfer speed (not internet access) do you give up by going to wireless?
>
> --
>
> Jeff McPherson
> Email address deliberately false to avoid spam
> (E-Mail Removed)
> Outgoing mail is certified Virus Free by AVG
>
>

Hactar wrote:

>> 10BaseT gives you 10Mb/sec (assuming full duplex)
>> 100BaseT gives you 100Mb/sec (ditto)
>
> I believe it's actually 20 and 200 respectively. Can anybody confirm or
> deny?
>

You cannot exceed the data rate for wired ethernet and for that matter even
reach it, due to overhead etc. However, if configure for full duplex, the
combined send & receive data rate may be close to 20 or 200 Mb. Wireless
on the otherhand, is half duplex, with more overhead than on ethernet and
you don't have collision detection. This means that the usable capacity
would be somewhat less than a comparable bit rate on ethernet.


--

Fundamentalism is fundamentally wrong.

To reply to this message, replace everything to the left of "@" with
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On Sat, 03 Jan 2004 19:39:29 GMT, in alt.internet.wireless , James
Knott <(E-Mail Removed)> wrote:

>Hactar wrote:
>
>>> 10BaseT gives you 10Mb/sec (assuming full duplex)
>>> 100BaseT gives you 100Mb/sec (ditto)
>>
>> I believe it's actually 20 and 200 respectively. Can anybody confirm or
>> deny?
>>
>
>You cannot exceed the data rate for wired ethernet and for that matter even
>reach it, due to overhead etc. However, if configure for full duplex, the
>combined send & receive data rate may be close to 20 or 200 Mb.

Assuming its true (and I'm not convinced, I believe that 100 half ==
50 either direction), this a very very uncommon scenario. How often do
you actually transfer in both directions simultaneously?

>Wireless
>on the otherhand, is half duplex, with more overhead than on ethernet and
>you don't have collision detection. This means that the usable capacity
>would be somewhat less than a comparable bit rate on ethernet.

Considerably less!

Mark McIntyre


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