[e2e] Internet packet dynamics

[Sam Liang]

On Fri, Mar 12, 2004 at 09:44:20PM -0500, David G. Andersen wrote:
> On Fri, Mar 12, 2004 at 04:46:27PM -0800, Sam Liang scribed:
> > 
> >   Vern Paxson's excellent Sigcomm 97 paper, "End-to-End Internet Packet
> > Dynamics", told us a lot about the Internet traffic characteristics. But
> > seven years have passed. The Internet has changed a lot. In particular, the
> > packet loss rate has dropped a lot. But it's not zero.  Are there any 
> > recent work that study the current Internet traffic patterns, 
> > such as packet loss rates?
> 
>  Quite a few.  You can get some packte loss numbers in a more
> recent IMC paper of mine, and I'm sure there are numerous
> other sources:
> 
>   http://nms.lcs.mit.edu/papers/bestpath-imc2003.html
> 
>   As you assume, the loss rate we observed in 2002-ish is much lower
> than observed by Paxson97.  The e2e loss numbers we observed
> in the 2001 RON study were also quite a bit lower than those
> that Paxson saw.  Those 5 years were a pretty good period for
> internet bandwidth growth and technological improvement.

  Thanks for the info. 
  You said 38% of the time, the loss rate is less than 0.2%, which means
that 62% of the time, it's higher than 0.2%. I think this implies two
things. First, such loss rate seems good enough for voice over IP, even
without error recovery. Second, for video streaming, 0.2% is still pretty
bad.  I am trying to evaluate the severity of packet loss effect on today's
Internet on real-time multimedia communication.

  One quick question. In your paper, you seem to suggest that sending
the same packet back-to-back along the same path get about the same
benefit as sending packets along different paths. If the packet loss is
caused by congestion, aren't you aggravating the congestion condition by
doubling your transmission rate?  And isn't it going to increase the
packet loss rate?

  Thanks,

Sam