Be on the wave or under it
The News – 11/08/01
of Service is in the Eye of the Beholder
At a recent talk sponsored by the new University of Minnesota Digital Technology Center,
Dr. Angela Sasse, an interaction design expert from University
College, London, UK, presented a different view of Quality of
Service (QoS) than the one traditionally taken by network experts.
QoS is a term that seeks to measure the efficiency
of a network in delivering a data stream, for example, a digital
audio or video data stream. One of the reasons that QoS is of
concern to network managers has to do with the packet-oriented
nature of networks like the Internet.
When you deliver voice over the phone network,
you may have QoS concerns such as noise and voice quality, but
generally what you put in one end almost always comes out the
other end. This is because the phone network sets up dedicated
circuits between you and Aunt Tillie. All traffic (voice) between
the two of you travels over the same path (I’m oversimplifying
here, I know) for the duration of the call.
When you try to stream data over an Internet
Protocol (IP) network like the Internet, the data is segmented
into packets. The packets are numbered and sent out onto the network
toward their destination. Unlike a circuit-switched network like
the telephone network, packets on a packet-switched network can
take different routes to get to their destination. This can lead
to QoS problems.
Depending on network congestion, packet #1 can
arrive at the destination well after packets #2 through #10. This
is partly because current packet-switched networks can’t distinguish
between critically important packets that may be part of a time-sensitive
video stream, for example, and packets that are part of a casual
email. As a result, packets may arrive so out of synch (or even
fail to arrive at all) that the application playing the video
stream on the receiving end must drop them and get on with it.
When packets are dropped, the picture can freeze
or the audio can stutter, like Max Headroom (for all
you 80s freaks).
Network engineers typically will measure the
quality of a particular network transmission based on how many
packets are dropped at the receiving end. The general benchmark
is, if the viewer experiences 20 percent packet loss, QoS is judged
as unacceptable. Most people don’t mind up to 5 percent packet
Dr. Sasse’s research, on the other hand, indicates
that there are many other, psychologically based variables in
a user’s assessment of QoS. In fact, many of these variables can
be much more important than raw measures of packet loss. Among
her findings was the astonishing observation that only 16 percent
of subjects noticed the difference between video streamed at 5
and at 25 frames per second (fps). (For reference, US TV is 30
fps (or 29.97
fps if you’re really anal); movies are 24 fps; silent films
were around 15 fps; there’s a new
camera that can capture up to 1 million fps.) Further, there
was a disjoint between users’ awareness of the stress caused by
a bad connection and the physiological measurement of that stress,
which brings up the question of whether users might erroneously
attribute their feelings of stress to the content rather than
its inadequate delivery. But by far the most interesting finding
was that, when a pay for quality model was introduced, uses suddenly
became very tolerant of 20 percent packet loss, which people normally
find unbearable. So I guess the moral is: If people are complaining
about the quality of your service, start charging for it, and
they’ll shut up.
The overall finding of Dr. Sasse’s research is
that most often users are engaged with the subject matter and
not the delivery. If the content is very interesting, such as
a videoconference among co-workers on a project team, users are
able to tolerate quite terrible QoS. If the content is not gripping,
such as a boring keynote speech from a seminar, delivery glitches
become much more annoying.
Now if we can just convince the network guys
that Content is King!
- Shameless Self-Promotion
Dept.: Look for a new directory, debuting
this week: Nanotechnology Resources. Frankly, I was overwhelmed
at the amount of information on the Net about this technology
and thus didn’t get the directory finished in time for the article
in the previous SNS. It will feature
commercial and academic resources along with pointers to other
directories and link pages.
Geek Shirt: This one’s for the geeks among
us. For the rest, a little explanation: In the UNIX operating
system, many important commands and applications are stored
in a directory called /bin, or in subdirectories of it. To remove
a subdirectory, you give the rm (remove) command followed by
“switches,” which are options to the command. The switches “rf”
mean recursively (repeatedly) remove all files, and ignore any
problems you may encounter on the way. Thus, rm –rf /bin/laden
means: “Terminate /bin/laden with extreme prejudice.”
Of course, if you have to explain it, it’s not too funny, right?
But at least now you’ll know what it means if you see a UNIX
geek with this shirt.
- Roadrunner Won’t Support XP: Road Runner, the second-largest
cable Internet service provider (ISP) has said it won’t support
Microsoft’s Windows XP, released last Wednesday. This means
Road Runner’s 1.4 million subscribers will be on their own if
they upgrade to the new operating system.
A Road Runner customer service technician said it could take
up to a year for everyone to get trained on the new OS. “We're
not able to support Windows XP technical support-wise -- people
can still put it on their computer, but we won't be able to
help them out,” the technician said. “I expect that all the
technicians will be trained in (XP) soon,” meaning within the
Is this the latest salvo in the war between Microsoft and AOL
Time Warner, majority owner of Road Runner. AOL Time Warner
is the largest ISP in the world; Microsoft is the second-largest.
The two companies have been sniping at one another since Microsoft’s
offer to combine and rule the world was rejected.
- Stupid Quote Alert: As previously revealed, I subscribe to
Emazing’s Stupid Quote of the Day service. Most of the quotes
aren’t really stupid, but this one sure is interesting:
“If the queen
is walking on a royal estate, miles from a landline phone, she
can stay in contact. It was a bit of a novelty at first, but
now it is second nature.”
- From a senior courtier of Queen Elizabeth's court, commenting
on the Queen getting her own mobile phone (although she has
banned her servants from carrying them).
OK, the strange thing revealed here, from my perspective, is
not that the queen has a cell phone (and I invite readers to
send in best guesses as to what her number would be, keeping
in mind that British phone numbers have approximately 11 digits)
but that there’s still such a thing as a courtier!
- I Want This Phone: Sprint is offering the $500 Sanyo 5000
phone, which allows you to attach a picture to a directory entry.
When the pictured person calls you, you get video caller ID,
and the picture pops up for you to admire. Simple, but pretty
cool. The phone also features an audio note-taking feature,
Wireless Web, a 2-inch 256 color display with back light, and
image editing software, presumably for your PC. Sanyo claims
it is the first color phone in the US.
- Cyberprotests a Threat? The National Infrastructure Protection
Center has released a report entitled, Cyber Protests: The
Threat to the U.S. Information Infrastructure. The
report claims that as the power and sophistication of home computers
increased, cyber protesting and so-called hacktivism will become
more significant to US national interests.
The primary technique used will be Denial of Service (DoS) attacks.
Cyber protest attacks have been on the rise since 1998, according
to the report, and are targeted at government sites as well
as commercial or cultural sites. The report analyzes Chinese,
Israeli and Palestinian, Indian and Pakistani, and Japanese
hacking attempts. The report offers no specific solutions, other
than “Pro-active network defense and security management.”
- A Really Dumb Site: If you like the feeling of superiority
that washes over you when you read about dumb people and dumb
stunts, you’ll love Dumb.com, a compendium of dumb crooks, stupid
questions, and helpful how-to features like “How to Drive Like
a Moron.” The latest
dumb criminal: a guy who offered to buy 56 grams of cocaine
from a uniformed policeman in his squad car.
- Richochet Rebounds: I reported the demise of Metricom’s
Richochet 128Kbps wireless modem service in a previous
SNS. Looks like others thought it was too good an idea to
die. Aerie Networks said it will pay $8.25
million to bankrupt Metricom for its wireless network, once
valued at $1 billion. Aerie once bid $20 billion for the system.
Good things come to those who wait. (Pet Peeve Alert: The link
to Aerie’s media kit on their Web site doesn’t work. That’s
a good way to get press!)
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