Read other letters about this article

• Tuesday, June 10, 2008 06:56 AM

  @ macgupta

  What the Internet provider should be selling you is a committed bandwidth rate - which is a guaranteed bandwidth, you will alway s have at least that much throughput - and a burstable rate, which is the maximum throughput you can have in ideal conditions. The 5Mbps that is hyped today is the burstable rate.

  Different services require different bandwidth profiles (and suffer to a greater or lesser degree when these requirements aren't met.

  VoIP require very low bandwidth, but it is continuous and must be with a very small guaranteed maximum latency (even with good echo cancellation, which becomes more difficult for longer latencies, you may have experienced the headache of talking on top of the other person when you have a sat line with long delays...).

  Streaming video requires a higher continuous bandwidth, but is a bit more tolerant to delays as long as they're not all over the place.

  Web browsing is very bursty, and it would be nice to have high bandwidth, but not necessary. Delays (shorter than a couple of seconds) are pretty much inconsequential.

  Protocols that require acknowledgement (such as TCP/IP) may have an effective bandwidth less than carrier bandwidth due to the acknowledgement window size (and in such instances, the bandwidth and latencies in both directions will come into play). Streaming video and VoIP are UDP/RTP (non-acknowleding protocols) for the data, but the control (SIP, etc.) is TCP.

  It's quite important to know the nature of the traffic (and even your benchmarks (such as DSLReports.com) use a range of traffic types in their computations (and the end number is an "average" of these).

  Simply guaranteeing bandwidth is not enough (and is wasteful too; even in the circuit-switched world, if the phone company had to guarantee you a channel, they'd have to overbuild tremendously [and mobile phone companys would be out of business; you've probably all heard "fast busy" or "all circuits are busy" announcements at one time or another).

  Telling you what the burstable rate is is useful (and is what they tell you most of the time, because it's the biggets number they can use), but only one of a number of things that will affect your customer satisfaction.

  </LECTURE>

  :-)

  Cheers,

  —Arne Langsetmo Read Arne Langsetmo's other letters
  Permalink
  Flag
  Click "Submit Flag" if you feel this post is inappropriate. Explain why below if you wish.

  Cancel