From: Michael Sinatra (michael@rancid.berkeley.edu)
Date: Tue Jul 22 2003 - 12:12:54 PDT
On Mon, 21 Jul 2003, Greg Merritt wrote:
>
> Our administrative office staff (accounting, payroll,
> personnel, grants, etc.) here at the Institute of Transportation
> Studies use mostly Macs. What other departments/groups on campus are
> predominantly Macintosh for administrative functions?
This discussion reminded me of something Tom H. asked me to do a long
while back, which is to provide a *rough* estimate of the number of
Apple/Mac devices on campus using CNS's ARP cache data. So here's what I
did:
CNS maintains "snapshots" of each day's ARP data over the past six months.
I looked at <http://standards.ieee.org/regauth/oui/index.shtml> and found
all of the registered MAC address prefixes that belong to Apple Computer.
I then chose some representative days and searched for the set of Apple
MAC (pardon the pun) addresses for each day. I removed duplicates and
compared the resulting number to the days full data (again with duplicates
removed). Duplicates would be caused by one machine changing networks/IP
addresses during the day, changing airbears networks or getting a new dhcp
address durning the day, etc. I then computed the percentage of Apple MAC
addresses to the total. This would represent the percentage Apple/Mac
devices powered on and connected to the network at any time of the day.
I picked some representative days and here's what I found (each day is
measured roughly from midnight to midnight):
Monday, July 21, 2003: 3283 Apple, 20423 total (16.1%)
Saturday, July 19, 2003: 1811 Apple, 14241 total (12.7%)
Thursday, June 5, 2003: 3404 Apple, 20107 total (16.9%)
Tuesday, April 15, 2003: 4227 Apple, 27077 total (15.6%)
Tuesday, April 30, 2003: 4212 Apple, 27226 total (15.5%)
Monday, March 17, 2003: 4127 Apple, 26615 total (15.5%)
Saturday, February 8, 2003: 2338 Apple, 19351 total (12.1%)
Thursday, Jan 23, 2003: 4128 Apple, 26444 total (15.6%)
Thursday, Dec 19, 2002: 3445 Apple, 22457 total (15.3%)
Wednesday, Oct 30, 2002: 4100 Apple, 26593 total (15.4%)
CAVEATS:
1. We do not poll ARP data for the entire campus. Specifically, the
modems, EECS, University Extension, Space Sciences Lab, University Health
Services, and UC Printing are not polled, for a variety of technical
reasons. Also any host that is behind some sort of NAT box or non-briding
firewall will NOT show up in the ARP cache. The survey DOES include the
Res Halls.
2. Many network devices show up in the ARP cache and some have multiple
MAC addresses that may or may not show up in the cache. CNS has roughly
1500 manageable network devices on campus. These MAC address do not
represent actual USER HOSTS, so the percentage of Apple/Mac devices
compared to actual user hosts may actually be higher.
3. Some Apple/Mac devices may be using third-party networking devices,
which would NOT show up in this survey as an Apple/Mac device. It's also
possible that some Apple-branded devices *may* use third-party chipsets,
which may or may not show up as an Apple MAC address. This may imply that
the number of Apple devices is higher than the percentages show, but it's
not completely unknown what effect this has, if any.
4. This survey also includes network-attached printers and other devices.
It's possible that an all-mac shop uses an HP network printer or that an
all-PC shop uses an Apple network printer, but I have no idea how this
might skew the overall results, or if anyone cares.
END OF CAVEATS
The results look pretty consistent, with an obvious drop-off on weekends
of the total number of connected hosts. (It's nice to see that some
people turn their computers off over the weekend, thereby saving the
University money and making it (slightly?) less likely that we'll be
taking pay cuts soon.) Interestingly, the Macintosh percentage drops on
the weekend also. I draw the following possible conclusions from this,
with varying credibility:
1. A higher percentage of Apple/Mac computers are used for administrative
applications; hence, the higher weekday percentage.
2. Apple/Mac users are more environmentally and pay-cut conscious than
their Windows and (especially) Unix bretheren and sisteren. They are
therefore more likely to turn off their computers or put them into
power-saving mode on weekends.
3. Apple/Mac users are more possessive of their weekend leisure time and
are less likely to come to work on weekends. (I am sure some Mac fans
will say that they don't *have* to come to work on weekends because
they're so productive on their Macs.)
You can draw your own conclusions, too.
michael
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