dotan_ak@yahoo.com hath wroth:
>I merely wanted you to know that I know a thing or two about networking.
>I should have mentioned my 7 years in the industry... I'm proud of my
>certifications (...)
I just couldn't a perfect target when presented to me. It's a
constant subject of debate (and irritation) among my few remaining
friends and aquaintences. Also, be advised that all experience and no
theory also has its limitations. One of my early mentors was a self
taught genius (literally). To him, learning anything new came easily
and was obvious, while I stuggled to understand. However, he often
managed to overlook obvious issues that were basic to anyone that had
a formal electronics education. He eventually had to go back to skool
to get a decent basis for what he learned from extensive experience. I
often see this is myself, where I know how to fix or do something, but
have only a limited understanding on how it works under all the
acronyms. If anything, certifications exposes a person to things that
one would normal not care much about (SNA, X.25, IPX/SPX, etc).
>Both computers wired: 92.6 Mbits/sec
Perfect.
>1 wireless (server) and 1 wired (client): 19 Mbits/second. The
>reported connection speed at that time was 54 Mb/s.
If you have 802.11b compatibility enabled, and a connected 802.11b
client, that's about what you would get. Actually, it would be a bit
less. The maximum speed with 802.11b compatibility disabled, and
running in 802.11g mode would be about 24Mbits/sec. You should see
something close to that but your about 12% low. My guess(tm) is that
you have the Afterburner (Speedboost) mode enabled, but are not using
it. Dive into the WRT54GS setting and turn it off. Methinks you
should then see something closer to 24Mbits/sec thruput. You might
also be seeing some intereference. Try other channels (1, 6, or 11)
and see if the speed improves.
Of course, all this begs the question "What thruput speed were you
expecting"? It is possible to have greater than 25Mbit/sec thruput
using proprietary enhancements such as Afterburner. Just purchase a
compatible client card. You already have the correct router. However,
I don't think you'll be too happy with it because the range at
>54Mbit/sec connections is very limited. Various reviews (which I'm
too lazy to find) on the WRT54G indicate that the speed vs range
tradeoff is not too wonderful for Afterburner. This might be worth
reading as a reality cheque:
<http://74.52.135.83/content/view/24861/99/1/1/>
On the other foot, some of the MIMO router are demonstrating really
impressive speed versus range curves. If you really want to go faster
than 20-25Mbits/sec or go through walls reliably, you might consider
one of these.
>Unfortunately, I didn't have the 2nd wireless card with me so I
>couldn't run the test with both computers connected to the access
>point.
Assuming the access point doesn't add any additional latency, you're
wireless to wireless thruput should be half again or 12 Mbits/sec
maximum between 802.11g only clients.
>So if I understand correctly (based on field experience :-) ), that
>proves that my router and access points are just fine.
Ahem. Based on how closely you're results match theoretical limits, I
would say you're 12% low in speed. Close, but some tweaking might be
useful. However, based on extensive experience, none of which I've
bothered to record or tabulate, I would say your 19Mbits/sec TCP
thruput is typical for a default configured wireless router.
>Is there an
>unusual overhead for packets from the web that are destined to a
>wireless client?
No, and that is a problem. Your previous benchmarks of 7Mbits/sec
need to be explained. The wireless only performance is "good enough".
The wired performance to the internet at 15Mbits/sec is also running
at the best that the cable modem can deliver. Something else is going
on here that is only common to wireless plus internet. Time for some
more testing.
Go unto:
<http://nitro.ucsc.edu>
and try the tests. Look under "more details" and "statistics" and see
if they offer some more clues. If you have a TCP RWIN problem, or
something similar on your client, it will show it. Also, UCSC.EDU is
on the left coast. See the list of other WEB100 servers at the bottom
of the page for something closer.
Also, there is quite a bit of detail that can be extracted from IPerf
run over the internet. However, I have a problem. I know the IP
address of several IPerf servers on the internet, but I don't know if
I'm allowed to disclose them to the GUM (great unwashed masses). I'm
going to play it safe and keep my big mouth shut. However, a Google
search will find a few. No long tests please as IPERF will saturate
the ISP's backhaul.
>I can theoretically call my ISP but they'll most likely blame it on the
>Linksys equipment...
That depends on the ISP. Ask them to setup an IPerf server so that
you can do your own testing and not bother their support people.
Unfortunately, I can't even convince my own ISP's to do that, so your
chances of success are probably limited. Still, it's worth a try.
>Any suggestions would be welcome.
Benchark, test, reconfigure, substitute components, borrow a different
router, try same tests at a friends, and whatever you do, make NO
assumptions. Use your own system to learn the limitations and effects
of various parameters. For example, use IPerf to make a graph of
connect speed, thruput, and range. When things are finally deemed
stable, record some benchmarks so that you have a basis for what
constitutes "normal". Extra credit for setting up SNMP and graphing
performance changes over time using MRTG, PRTG, or RRDTool.
--
Jeff Liebermann
jeffl@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