StratVantage News Summary 11/08/01
Quality 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, likeMax 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 loss.
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 next year.
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!)