Thank you, orinoco_cs
jimc at math.ucla.edu
Wed Sep 25 09:15:19 EST 2002
On Tue, 24 Sep 2002, Timothy Murphy wrote:
> (1) I'm not clear on the requirements for mode, ESSID, etc.
> In my case it does not seem to matter whether I set mode
> to ad-hoc or managed;
> I cannot set mode to master, or change the ESSID,
> at least while the card is active
> (as opposed to changing the relevant entry in /etc/pcmcia/wireless.opts).
The MAC address of 02:02:2D:4A:52:80, is that the address of either of your
cards? If not, it's the address of your neighbor's access point :-) My
/etc/manuf file does not list 02:02:2d:*, but 00:02:2d belongs to Avaya.
The mode should be Managed if you're using an access point, or Ad-Hoc if
not. In Ad-Hoc mode, both (all) cards must have the same ESSID and channel.
In Managed mode you don't set the channel (the AP setting is
authoritative), and some cards will let you set an ESSID of "any" to
connect to the first network encountered, and some cards have this setting
as the power-on default.
> (2) What exactly is the significance of the entries
> for Link Quality, Signal level and Noise level ?
> Are they accurate;
> or if not, is there any other way of determining
> how sensitive the card or cards are?
Signal and noise level are in dB relative to a non-obvious origin, so an
increase of 3 dB (i.e. less negative) corresponds to doubling the signal
(or noise). "Link quality" means the difference of these, the signal to
noise ratio, which is what really determines how fast the link can run.
Over 10 dB is marginally adequate; over 20 dB is good. In Managed mode the
statistics for the access point are reported automatically. In Ad-Hoc mode
they're all zero unless you do "iwspy eth0 $adr" where $adr can be either
the MAC or IP address of the station you want stats about. In your case it
looks like the cards can't identify the access point, and so are giving all
The dB origin for signal or noise varies from one vendor to another, but if
one brand of card reports a higher "link quality" for the same partner, it
will lose fewer packets or can operate at a greater distance. If the
partner's card is replaced, with the same receiving card, a higher number
means the partner is transmitting more power. 33 and 50 milliwatts are the
powers I've seen mentioned on the list. Check the tech specs of your card,
in the printed material or on Avaya's web site.
> (3) On a slightly different tack,
> what is the relation between Avaya, Agere, Lucent, Orinoco,
> Wavelan and IEEE?
> Has Lucent licensed the Orinoco hardware or software
> to companies such as Avaya?
In the USA, AT&T was forced to divest itself of the Regional Bell Operating
Companies, but kept Bell Telephone Laboratories, Western Electric
(manufacturing), and the long distance business. Later it spun off Lucent,
which included Bell Labs and Western Electric. During the dot-com bubble,
Lucent decided to concentrate on its core competencies and not have its
balance sheet weighed down by dull, plodding, old-tech manufacturing
organizations, so it spun off Avaya (Western Electric: central office
switches, cabling systems, connectors, etc.) and Agere (microwave
manufacturing). In its heyday Lucent traded for US$ 85/share. It is now
down to just above $1. Anyone want to guess how many shares I own?
Wavelan is a registered trademark of NCR Corporation (I think), formerly
National Cash Register Corp., which was swallowed by AT&T (I think it was
before Lucent and ended up in the Lucent spinoff). This was their line of
very early wireless cards at 1 Mb/s using I think a proprietary protocol.
Orinoco is a registered trademark of Agere Corp, formerly held by Lucent,
referring to their line of 802.11b wireless products.
IEEE is the Institute of Electrical and Electronic Engineers, a USA
professional society which has an extensive standards activity. In
particular, IEEE 802.* governs Ethernet-style packet communications, with
variants for a broad range of physical media.
> (4) As a matter of (minor) interest,
> why does the PCMCIA card give a bit-rate of 2Mb/s,
> while the PCI card claims 11Mb/s ?
The instances you showed are in Managed mode. I can think of a few
a. The cards are sort of doing managed ad-hoc mode, and aren't getting the
right packets back from the nonexistent access point, and are responding
differently. Cure: set up Ad-Hoc mode properly.
b. You're associated with the neighbor's AP, and the PCI card has a good
signal path while the laptop is behind an obstruction.
c. If you see this in Ad-Hoc mode, there's a notorious problem with
Intersil firmware (Linksys, D-Link, NetGear, etc.) Using the orinoco
driver suite, it used to work fine, but now the cards fail to send 802.11b
ACK packets, so their partners think the link has gone bad, and they reduce
the speed to compensate, besides retrying transmissions a zillion times.
In the worst case, throughput goes down to 21 Kbyte/sec, hiss, boo! It's
possible that there's no blame in the orinoco driver, but a firmware
upgrade to 1.0.3 (Intersil) is the cause.
> (5) I always get the warning about different versions
> (12 against 14 in this case).
> Does it really matter?
> And if so, what can one do about it.
Definitely start reading at:
He discusses a lot about wireless LANs. From the subdirectory on wireless
tools, download the latest version, compile it, and install it. It's also
possible that your Linux distro has a precompiled updated version in RPM
format, which would be more palatable when you go to upgrade your distro;
dig around on the FTP site for the most recent distro version.
The statistics block given by a driver compiled with wireless tools version
14 is not exactly backward compatible, so a version 12 iwconfig will exit
with a segmentation fault. It doesn't seem to do any harm, but still, it's
a good idea to keep the driver and tools at the same version level.
James F. Carter Voice 310 825 2897 FAX 310 206 6673
UCLA-Mathnet; 6115 MSA; 405 Hilgard Ave.; Los Angeles, CA, USA 90095-1555
Email: jimc at math.ucla.edu http://www.math.ucla.edu/~jimc (q.v. for PGP key)
More information about the wireless