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<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=039404400-17092002>I
don't know about the wireless side, but I can tell you
that Ethernet uses CSMA/CD (Carrier Sense, Multiple Access,
Collision Detection) to modulate the carrier (radio frequency)
.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=039404400-17092002>Only
one device can talk at one time per "Carrier" - thus, on Ethernet if you have
multiple devices (MA) sharing the carrier and create "two way"
communications (ie. pings originating from both ends) - the packets could
collide, a pause will occur and they will retry. (/CD) - slowing down your data
path.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=039404400-17092002></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=039404400-17092002>THEN,
also don't forget, that whilst the CARRIER communicates at "10Mb" - you are
encoding with protocols to transport the data ie. </SPAN></FONT><FONT face=Arial
color=#0000ff size=2><SPAN class=039404400-17092002>802.3 Frame, Ip Protocol,
TCP protocol etc. All of these carry the payload (read: data) that you are
sending. </SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=039404400-17092002>I
would also guess that if you are also encrypting you should (theoretically) have
packet "padding" to filling up any partially-filled frames -
so it will also affect the throughput of the of path (not forgetting the
time it takes (latency) to encrypt and decrypt etc)</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=039404400-17092002></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=039404400-17092002>Finally, there is Latency. This is the time it takes to
get from one side of a device to another. For example, in a router you expect
latency, because the router has to strip the Frame (802.11 or 802.3),
investigate the IP Addresses and protocol, make a decision and then forward it
onto the next interface. All of which takes time - thus affecting the
throughput.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=039404400-17092002></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=039404400-17092002>So I
would assume that, like Ethernet, in wireless you wouldn't get actual 11Mbs
of data passing over a link, just like you will not get "10Mb" of data over an
Ethernet link. (In fact, I believe that the throughput of Ethernet is about
3.9Mb)</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=039404400-17092002>I
can't tell you what to expect on a wireless link (I don't have those figures) -
but look for throughput - it is a better representation.</SPAN></FONT></DIV>
<BLOCKQUOTE>
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> Rowan Wainwright-Smith
[mailto:Rowan@teleaudit.com]<BR><B>Sent:</B> Tuesday, 17 September 2002
9:15<BR><B>To:</B> Cameron Donaghey<BR><B>Subject:</B> Re: [MLB-WIRELESS]
Transfer Rates<BR><BR></FONT></DIV>Cameron,<BR><BR>transfer rates are a little
tricky, 'coz there are two ways of measureing them<BR><BR>1
PURE Bandwidth - how many BITS per second!<BR>2. Transfer
performance (usually measured in BYTES per second)<BR><BR>The stats you are
getting are pretty reasonable, but you should be able to get about
550(-600)k/sec <BR><BR><BR>these cards are 11 Mbit,<BR><BR>if you work it out,
you are getting about 2.5mbit transfer rate (not counting TCP overheads) Bear
in mind that these devices are 11mbit TOTAL bandwidth, so if you have two PC's
communicating, then you can really only expect up to approx 5Mbit transfer,
3PC's then about 3.5 Mbit & so on.<BR><BR>Wireless is NOT switched
bandwidth like most modern wired networks, but shared (like running a hub
instead of a full switch)<BR> Personally not sure about what effect using
an AP is having, but this *could* be reasonable!<BR><BR>maybe the rest of the
list can help you more....<BR><BR>well done on getting your WLan up &
running!<BR><BR>Rowan<BR><BR>Cameron Donaghey wrote:<BR>
<BLOCKQUOTE cite=mid:5.1.0.14.2.20020916154805.00b22050@pop-server
type="cite">Hello Everyone,<BR> I have eventually got my wireless up
and running, only on a private level at the moment, and<BR>yet I am not
entirely sure it is running correctly. I have two machines and in each one I
have<BR>a Compaq WL100 card set to infrastructure mode. I also have a
linksys Wap11 access point<BR>which is running as an access point only.<BR>I
have done some testing and I seem to have a max. transfer rate between the
two machines<BR>of about 310kb/s and the machines are only a meter or so
apart. I would have assumed that<BR>being a 11mb/s network that I would be
able to achieve more so around 500-1000kb/s rather<BR>than the 300kb/s max.
I am currently achieving. Both card say they have "excellent
connections"<BR>and at 11mb/s.<BR>My question to you all, is the transfer
speed of about 300kb/s typical for 802.11b or should I be<BR>able to achieve
higher rates of transfer? If I should be able to achieve more would anyone
have<BR>any suggestions towards resolving the problem?<BR> Thanks very
much,<BR> Cameron Donaghey<BR><BR></BLOCKQUOTE>
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