[xcp] Re: New XCP expr results

[Aaron Falk]

Yongguang-

Many thanks for the pointer to the paper.  Tom Henderson told me about 
the work you've been doing and I look forward to reading about the 
details.  Would you be interested in giving a talk on it at ISI?  
(Non-ISI folk on this list would, of course, be welcome to attend.)

Drop me a line privately and we can work out the details,

--aaron


On Aug 7, 2004, at 2:15 AM, Yongguang Zhang wrote:

> Dear Colleagues,
>
> We have done some experimental study on XCP in a real test bed.
> The manuscript explaining the results is placed (temporarily) at
> http://www.yongguangzhang.net/research/xcp.html.
> The abstract is also included below.  We solicit all your comments
> on this work.  Thanks!
>
> Aaron: do you still have regular XCP meetings down in ISI?
> Maybe I can come down sometime and talk about this.
>
> Regards,
>
> Yongguang
>
>
> ====
> An Implementation and Experimental Study of the eXplicit Control 
> Protocol (XCP)
>
> Yongguang Zhang and Tom Henderson
>
> The eXplicit Control Protocol (XCP) has been proposed as a
> multi-level network feedback mechanism for congestion control of 
> Internet
> transport protocols. Theoretical and simulation results have suggested
> that the protocol is stable and efcient over high bandwidth-delay 
> product
> paths, while being more scalable to deploy than mechanisms that do 
> require
> per-ow state in routers. However, there is little operational 
> experience with
> the approach. Since the deployment of XCP would require changes to both
> the end hosts and routers, it is important to study the implications 
> of this
> new architecture before advocating such wide scale changes to 
> internets.
> This paper presents the results of an experimental study of XCP. We
> first implemented XCP in the Linux kernel and solved various systems 
> issues.
> After validating previously reported simulation results, we studied
> the sensitivity of XCP's performance to various environmental factors 
> and
> identied two sources that can signicantly reduce XCP's ability to 
> control
> congestions and achieve fairness. Our contributions are two fold. 
> First,
> through implementation we have revealed the challenges in platforms 
> that
> lack large native data types or floating point arithmetic, and the 
> need to
> keep fractions in XCP protocol header. Second, through experiments and
> analysis we have identied several possibilities that XCP can enter 
> into incorrect
> feedback control loops and adversely affect the performance. These
> are deployment challenges intrinsic to XCP design. More research is 
> needed
> before we can advocate a wide scale adoption.
>
>
>