Re: [tsv-area] TANA BOF

[Stanislav Shalunov <[e-mail]>]

On Aug 1, 2008, at 4:26 AM, Roland Bless wrote:
> It is not clear to me how "otherwise idle bandwidth"
> can be made available for pure end-to-end transport
> solutions, i.e., without differentiation in the
> network itself.

On a technical level, we can definitely design and implement end-to- 
end congestion control that yields to (New)Reno -- or, in fact, to any  
loss-based congestion control.  In fact, I happen to have done just  
that for a particular application that currently uses up a larger  
fraction of bits on the Internet than any other app with the possible  
exception of HTTP.  Delay-based congestion control schemes yield to  
loss-based control quite often regardless of whether they are designed  
to do this simply because delay needs to increase to buffer size  
before loss occurs.

> a) probably it is easier to start deploying
> RFC 3622 (http://tools.ietf.org/html/rfc3662)
> in ISP networks than to design new
> congestion control algorithms. All you need
> is a DSCP, a codepoint classifier, a separate
> queue and simple priority scheduling. CS(1)
> DSCP=001000 was proposed for LE traffic.

Yes, we tried that (http://qos.internet2.edu/wg/wg-documents/qbss-definition.txt 
  -- note dates on the documents: March 2001 for qbss, June 2002 for  
draft-bless-diffserv-pdb-le-00.txt).  We may like or not like it, but  
scavenger has not been deployed.

No, it is definitely not easier to upgrade the Internet than to design  
end-to-end algorithms that can be deployed by putting them into  
relevant applications.  This is a matter of deployment properties: to  
reach 80% deployment, one requires to change hundreds of millions of  
physical devices of thousands of different kinds, with virtually none  
of them on auto-update; the other requires to change a few pieces of  
software, all of them on auto-update.

The most congested links are uplinks of home connections.  We're not  
going to see the devices at their head ends changed any time soon.   
When they are changed, they will likely not support whatever scheme we  
like until there's a good reason to.  Whereas we can deploy end-to-end  
congestion control, and it'll work across these links.

Thank you for the comments,

-- Stas

--
Stanislav Shalunov