Revising Congestion Window Validation (CWV) in Standard TCP

NewCWV proposes an update to RFC 5681 to address issues that arise when TCP is used to support traffic that exhibits periods where the sending rate is limited by the application rather than the congestion window. It provides an experimental update to TCP that allows a TCP sender to restart quickly following either a rate-limited interval. This method is expected to benefit applications that send rate-limited traffic using TCP, while also providing an appropriate response if congestion is experienced. This is a current work item of the IETF TCPM working group.

The new-CWV specification:

• TCP to support Rate-Limited Traffic, draft-ietf-tcpm-newcwv, IETF Work-in-progress, TCPM WG. http://tools.ietf.org/html/draft-ietf-tcpm-newcwv

Support for new-CWV In Linux kernel:

• A Linux LKM (Loadable Kernel Module) implementing new-CWV is made available through Github
  at : https://github.com/rsecchi/newcwv/tree/05d0cbf40e18440883d743aecc42444d1433b327
  • The Github site as well as the README file in the package includes instructions on how to compile, install and use the software. The module has been tested with Linux kernel 3.8.2. However, it should be possible to compile and use the module with Linux systems other than kernel 3.8.2.
• A Linux TCP Kernel update is available in Linux kernel 3.14 (compatible with multiple CC).
  • Note: After Linux 3.15.10 the kernel includes an update to TSO that conflicted with the above.

Support for new-CWV In FreeBSD kernel:

• Early implementation work: Aris Angelogiannopoulos, MS thesis, at https://eggert.org/students/angelogiannopoulos-thesis.pdf.
  • PRR and NewCWV for FreeBSD RFC 6937 & draft-ietf‐tcpm‐newcwv, Performance of above: http://www.ietf.org/proceedings/89/slides/slides-89-tcpm-8.pdf
• Patch ( freedbsd-net, 30/6/2014) based on latest draft, Tom Jones, School of Engineering, University of Aberdeen.

Analysing application usage and behaviour of RFC2861 CWV:

• Md. Israfil Biswas and Gorry Fairhurst, A Practical Evaluation of Congestion Window Validation Behaviour, 9th Annual Postgraduate Symposium in The Convergence of Telecommunications, Networking and Broadcasting (PGNet 2008), 23 - 24 June 2008, Liverpool, UK.
• Md. Israfil Biswas and Gorry Fairhurst, An Investigation of TCP Congestion Window Validation over Satellite Paths, 4th Advanced Satellite Mobile Systems Conference (ASMS 2008), 26-28 August 2008, Bologna, Italy.
• Md.Israfil Biswas, Arjuna Sathiaseelan, Gorry Fairhurst and Raffaello Secchi, Analysing TCP for Bursty Traffic, Int'l J. of Communications, Network and System Sciences (IJCNS), Vol.3 No. 7, July 2010.
• I.Biswas, Internet congestion control for variable rate TCP traffic, PhD, University of Aberdeen, 2011.

new-CWV background:

• Original draft: Updating TCP to support Rate-Limited Traffic, draft-fairhurst-tcpm-newcwv, Expired, obsoleted by draft-ietf-tcpm-newcwv.
• Liu, Allman, Jiny, and Wang, Congestion Control without a Startup Phase, 5th International Workshop on Protocols for Fast Long-Distance Networks (PFLDnet), Los Angeles, California, USA", February 2007.
• G. Fairhurst & Md. Israfil Biswas; Updating TCP to support Variable-Rate Traffic, IRTF ICCRG presentation, draft-fairhurst-tcpm-newcwv (review by ICCRG prior to adoption by TCPM WG), IRTF ICCRG, Atlanta, November 2012.
• Arjuna Sathiaseelan, Raffaello Secchi, Md. Israfil Biswas and Gorry Fairhurst, Enhancing TCP Performance to support Variable -Rate Traffic, ACM CoNext Capacity Sharing WorkShop (CSWS), Nice, December 2012.
• Slides from TCPM at IETF-87 showing validation using pipeACK, http://www.ietf.org/proceedings/87/slides/slides-87-tcpm-3.pdf, 2013.

Analysing application usage and behaviour of newCWV:

• Aris Angelogiannopoulos, MS thesis, at https://eggert.org/students/angelogiannopoulos-thesis.pdf, Technical University of Munich, 2013.
• Slides from TCPM at IETF-90 showing performance of combining pacing with newCWV at https://tools.ietf.org/agenda/89/slides/slides-89-tcpm-2.pdf
• S Nazir; Z Hossain; M Broadbent; A Petlund; G Fairhurst; Performance Evaluation of Congestion Window Validation for DASH Transport, NOSSDAV '14 Proceedings of Network and Operating System Support on Digital Audio and Video Workshop, doi 10.1145/2578260.2578275, 2014,.
• Slides from TCPM at IETF-90 showing performance of draft -06 at www.ietf.org/proceedings/90/slides/slides-90-tcpm-0.pptx, 2014.

Documents and notes:

Some documents are archived in this directory: new-cwv files.