[e2e] Skype and congestion collapse.

[Cottrell, Les]

Great question. Though only a small sample, we also have made measurements to about DSL/ISDN/Cable 10 routers (5 ISPs) in homes in the SF Bay Area for several years now. We have data going back to Jan 1988.  The median losses have dropped from about 3% to about 0.02%, see http://www.slac.stanford.edu/xorg/icfa/icfa-net-paper-jan05/broadband.jpg   

-----Original Message-----
From: Jon Crowcroft [mailto:Jon.Crowcroft at cl.cam.ac.uk] 
Sent: Sunday, March 06, 2005 8:13 AM
To: Cottrell, Les
Cc: cannara at attglobal.net; End-2-End list; Jon.Crowcroft at cl.cam.ac.uk
Subject: Re: [e2e] Skype and congestion collapse.

it would be interesting to compare figures for commercial dialup and broadband ISPs wit hacademic - certainly when planetlab is used to study the net in terms of loss/throughput and connectivity, you can see how unrepresentative it is from The Interdoman Connectivity of PlanetLab Nodes. Suman Banerjee, Timothy G. Griffin, Marcelo Pias. Passive and Active Measurement Workshop (PAM) 2004. 
(papers accesible via
http://www.pam2004.org/
for interest)




In missive <35C208A168A04B4EB99D1E13F2A4DB01A0D71B at exch-mail1.win.slac.stanford.edu>, "Cottrell, Les" typed:

 >>Our measurements are using ping mainly between academic and research sites worldwide. The high losses in the US was several years ago. Typical losses between developed regions of the world (Canada, US, Europe, Japan, Korea, Singapore, Australia/NZ) are << 1%. Things have improved a lot. See for example Figs 3 and 4 of http://www.slac.stanford.edu/xorg/icfa/icfa-net-paper-jan05/.  There are high losses still in parts of the Internet but they are mainly to developing countries (see for example Figs 9 and 10 of the above report).  
 >>
 >>-----Original Message-----
 >>From: end2end-interest-bounces at postel.org [mailto:end2end-interest-bounces at postel.org] On Behalf Of Cannara
 >>Sent: Saturday, March 05, 2005 9:43 PM
 >>Cc: End-2-End list
 >>Subject: Re: [e2e] Skype and congestion collapse.
 >>
 >>On where congestion is occurring today in the Inet, it would be useful to ask Les Cottrell at SLAC how things have been going with their continued "ping-around-the-world" testing.  It had been true that busy peering points in the East & West of the US commonly lost 30%.
 >>
 >>Alex
 >>
 >>RJ Atkinson wrote:
 >>> 
 >>> On Mar 4, 2005, at 17:47, Clark Gaylord wrote:
 >>> > This is why we really do need some notion of QoS other than The Fat 
 >>> > Pipe.  It doesn't have to be as elaborate as RSVP-disciplined CAC, 
 >>> > but you need to be able to prioritize traffic that matters and limit 
 >>> > the amount of traffic that gets prioritized.  It doesn't have to be 
 >>> > more complex than that, but it has to do at least that.  [Ergo ... 
 >>> > left as an exercise to the reader.]
 >>> 
 >>> I don't know that the "network" needs to have a more sophisticated 
 >>> notion of QoS than best effort.  It can sometimes be useful for the 
 >>> network device connected directly to a congested link (e.g. access 
 >>> link between a site and its upstream provider) to have some 
 >>> internal-to-the-box QoS configuration.
 >>> 
 >>> It is not uncommon these days for the access router at the customer 
 >>> premise to have some ACL ruleset that prefers some traffic over other 
 >>> traffic or rate-limits certain kinds of traffic -- and equivalent 
 >>> configuration of the aggregation router on the ISP side of the same 
 >>> link is also not uncommon these days.
 >>> 
 >>> That said, most congestion today occurs either on an access link such 
 >>> as that or on some sort of wireless link (e.g. SATCOM to SW Asia).  
 >>> ISP core backbones tend to be over-provisioned.  Most campus 
 >>> (wired/fibred) networks are similarly over-provisioned.
 >>> 
 >>> Ran

 cheers

   jon