The NewReno Modification to TCP's Fast Recovery Algorithm
RFC 6582
Document | Type |
RFC - Proposed Standard
(April 2012; No errata)
Obsoletes RFC 3782
|
|
---|---|---|---|
Authors | Andrei Gurtov , Tom Henderson , Sally Floyd , Yoshifumi Nishida | ||
Last updated | 2015-10-14 | ||
Replaces | draft-henderson-tcpm-rfc3782-bis | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | WG Document | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 6582 (Proposed Standard) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Wesley Eddy | ||
IESG note | David Borman (david.borman@windriver.com) is the document shepherd. | ||
Send notices to | (None) |
Internet Engineering Task Force (IETF) T. Henderson Request for Comments: 6582 Boeing Obsoletes: 3782 S. Floyd Category: Standards Track ICSI ISSN: 2070-1721 A. Gurtov University of Oulu Y. Nishida WIDE Project April 2012 The NewReno Modification to TCP's Fast Recovery Algorithm Abstract RFC 5681 documents the following four intertwined TCP congestion control algorithms: slow start, congestion avoidance, fast retransmit, and fast recovery. RFC 5681 explicitly allows certain modifications of these algorithms, including modifications that use the TCP Selective Acknowledgment (SACK) option (RFC 2883), and modifications that respond to "partial acknowledgments" (ACKs that cover new data, but not all the data outstanding when loss was detected) in the absence of SACK. This document describes a specific algorithm for responding to partial acknowledgments, referred to as "NewReno". This response to partial acknowledgments was first proposed by Janey Hoe. This document obsoletes RFC 3782. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6582. Henderson, et al. Standards Track [Page 1] RFC 6582 TCP NewReno April 2012 Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. 1. Introduction For the typical implementation of the TCP fast recovery algorithm described in [RFC5681] (first implemented in the 1990 BSD Reno release, and referred to as the "Reno algorithm" in [FF96]), the TCP data sender only retransmits a packet after a retransmit timeout has occurred, or after three duplicate acknowledgments have arrived triggering the fast retransmit algorithm. A single retransmit timeout might result in the retransmission of several data packets, but each invocation of the fast retransmit algorithm in RFC 5681 leads to the retransmission of only a single data packet. Two problems arise with Reno TCP when multiple packet losses occur in a single window. First, Reno will often take a timeout, as has been documented in [Hoe95]. Second, even if a retransmission timeout is avoided, multiple fast retransmits and window reductions can occur, as documented in [F94]. When multiple packet losses occur, if the SACK option [RFC2883] is available, the TCP sender has the information to make intelligent decisions about which packets to retransmit and which packets not to retransmit during fast recovery. Henderson, et al. Standards Track [Page 2] RFC 6582 TCP NewReno April 2012 This document applies to TCP connections that are unable to use theShow full document text