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Making TCP More Robust to Long Connectivity Disruptions (TCP-LCD) (RFC6069)

IP.com Disclosure Number: IPCOM000202355D
Original Publication Date: 2010-Dec-01
Included in the Prior Art Database: 2010-Dec-14
Document File: 46 page(s) / 59K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

A. Zimmermann: AUTHOR [+2]

Abstract

Connectivity disruptions can occur in many different situations. The frequency of connectivity disruptions depends on the properties of the end-to-end path between the communicating hosts. While connectivity disruptions can occur in traditional wired networks, e.g., disruption caused by an unplugged network cable, the likelihood of their occurrence is significantly higher in wireless (multi-hop) networks. Especially, end-host mobility, network topology changes, and wireless interferences are crucial factors. In the case of the Transmission Control Protocol (TCP) [RFC0793], the performance of the connection can experience a significant reduction compared to a permanently connected path [SESB05]. This is because TCP, which was originally designed to operate in fixed and wired networks, generally assumes that the end-to-end path connectivity is relatively stable over the connection's lifetime.

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Internet Engineering Task Force (IETF)                     A. Zimmermann Request for Comments: 6069                                  A. Hannemann Category: Experimental                            RWTH Aachen University ISSN: 2070-1721                                            December 2010

    Making TCP More Robust to Long Connectivity Disruptions (TCP-LCD)

Abstract

   Disruptions in end-to-end path connectivity, which last longer than    one retransmission timeout, cause suboptimal TCP performance.  The    reason for this performance degradation is that TCP interprets    segment loss induced by long connectivity disruptions as a sign of    congestion, resulting in repeated retransmission timer backoffs.    This, in turn, leads to a delayed detection of the re-establishment    of the connection since TCP waits for the next retransmission timeout    before it attempts a retransmission.

   This document proposes an algorithm to make TCP more robust to long    connectivity disruptions (TCP-LCD).  It describes how standard ICMP    messages can be exploited during timeout-based loss recovery to    disambiguate true congestion loss from non-congestion loss caused by    connectivity disruptions.  Moreover, a reversion strategy of the    retransmission timer is specified that enables a more prompt    detection of whether or not the connectivity to a previously    disconnected peer node has been restored.  TCP-LCD is a TCP sender-    only modification that effectively improves TCP performance in the    case of connectivity disruptions.

Status of This Memo

   This document is not an Internet Standards Track specification; it is    published for examination, experimental implementation, and    evaluation.

   This document defines an Experimental Protocol for the Internet    community.  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).  Not    all documents approved by the IESG are a candidate for any level of    Internet Standard; see 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/rfc6069.

 Zimmermann & Hannemann        Experimental                      [Page 1]
 RFC 6069             Making TCP More Robust to LCDs        December 2010

 Copyright Notice

   Copyright (c) 2010 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 R...