Network Working Group M. Duke Internet-Draft Boeing Phantom Works Expires: April 8, 2005 R. Braden USC Information Sciences Institute W. Eddy NASA GRC/Verizon FNS E. Blanton Purdue University October 8, 2004 A Roadmap for TCP Specification Documents draft-ietf-tcpm-tcp-roadmap-00 Status of this Memo This document is an Internet-Draft and is subject to all provisions of section 3 of RFC 3667. By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 8, 2005. Copyright Notice Copyright (C) The Internet Society (2004). Abstract This document contains a "roadmap" to the Requests for Comments (RFC) documents relating to the Internet's Transmission Control Protocol Duke, et al. Expires April 8, 2005 [Page 1] Internet-Draft TCP Roadmap October 2004 (TCP). This roadmap provides a brief summary of the documents defining TCP and various TCP extensions that have accumulated in the RFC series. This serves as a rough guide and quick reference for both TCP implementers and other parties that need help consuming the vast cornucopia of TCP-related RFCs. Duke, et al. Expires April 8, 2005 [Page 2] Internet-Draft TCP Roadmap October 2004 1. Introduction One critical part of an Internet host's software is a correct and efficient implementation of the Transmission Control Protocol (TCP) [RFC0793]. As TCP has evolved over the years, many distinct documents have become part of the accepted standard for TCP. At the same time, a large number of more experimental modifications to TCP have been published in the RFC series. As an introduction to newcomers and an attempt to organize the plethora of information for old hands, this document contains a "roadmap" to the TCP-related RFCs. It provides a brief summary of the relevant RFC documents that define TCP. This can give rough guidance to implementers on the relevance and significance of various standards track extensions, informational notes, and best current practices This roadmap includes a brief description of the contents and relevance of each TCP-related RFC. In some cases, we simply supply the abstract or some key summary sentence from the text as a terse description. In addition, a letter code after each RFC number indicates its category in the RFC series: S - Standards Track (Proposed Standard, Draft Standard, or Standard) E - Experimental B - Best Current Practice I - Informational Note that the category of each RFC does not necessarily reflect its current relevance. For instance, RFC 2581 is nearly universally deployed although it is only a "Proposed Standard". Similarly, some "Informational" RFCs actually contain technical proposals for changing TCP. Section 2 lists the RFCs that form the core TCP specification. Section 3 lists some RFCs that provide suggestions for implementers or describe best current practices concerning issues raised by particular network environments. Section 4 lists RFCs that are experimental and may one day become standards, Section 5 lists some deprecated extensions, Section 6 contains case studies and analysis, and Section 7 provides tips and tools for implementers. Within each section, RFCs are listed in chronological order. When this document describes a features as "available in modern operating systems", we mean that the feature is at least present in widely deployed versions of today's Linux, BSD-derived, and Windows operating systems. Many other specific operating systems are in use on the Internet, and feature support varies widely both among them Duke, et al. Expires April 8, 2005 [Page 3] Internet-Draft TCP Roadmap October 2004 and among specific versions of even the few operating systems in the above list. However, if we say a feature is found in "modern operating systems", the reader may fairly safely bet that it can at least be found in most presently maintained commercial Unix flavors, Cisco IOS versions, and various real-time and embedded kernels that offer TCP support. Duke, et al. Expires April 8, 2005 [Page 4] Internet-Draft TCP Roadmap October 2004 2. Core Specification A small number of documents compose the core specification of TCP. These can be grouped into the base documents, describing things like the header format and state machine operation, documents describing congestion control behaviors, and documents that detail SACK use for efficient loss recovery. At this time every conformant TCP implementation should implement: Base protocol: RFC 793, as extended and clarified by RFC 1122, RFC 1323, RFC 2873, and RFC 2988. These documents are described in Section 2.1 Congestion control: RFC 2581, RFC 3042, RFC 3168, RFC 3390, and RFC 3782. Section 2.2 discusses these RFCs. SACK: RFC 2018, RFC 2883, and RFC 3517 are noted in Section 2.3 In addition to these core documents, there are a number of standards track documents that describe the TCP MIB statistics that are required to be kept. These documents are listed in Section 2.4 and their history is sketched, as a somewhat complex relationship exists between them. 2.1 Base Protocol RFC 0793 S: "Transmission Control Protocol", STD 7 (Sep 81) This is the fundamental TCP specification document. Written by Jon Postel as part of the Internet protocol suite's core, it describes the TCP packet format, the TCP state machine and event processing, and TCP's semantics for data transmission, reliability, flow control, multiplexing, and acknowledgement. Although the precedence and security compartment portions are mostly irrelevant today, the majority of this document still acurately describes modern TCPs. [RFC0793] RFC 1122 S: "Requirements for Internet Hosts - Communication Layers" (Oct 89) This document updates and clarifies RFC 793; fixing some specification bugs and oversights. It also explains some features such as keep-alives and Karn's and Jacobson's RTO estimation algorithms [karn][vj88]. ICMP interactions are mentioned and some tips are given for efficient implementation. RFC 1122 lists the various features that MUST, SHOULD, MAY, SHOULD NOT, and MUST NOT be present in standards-conforming TCP implementations. [RFC1122] Duke, et al. Expires April 8, 2005 [Page 5] Internet-Draft TCP Roadmap October 2004 RFC 1323 S: "TCP Extensions for High Performance" (May 92) This document introduces window scaling, timestamps, and protection against wrapped sequence numbers for efficient and safe operation over paths with large bandwidth-delay products. These are all commonly found in modern operating systems; however, they may require manual tuning and configuration. There are some corner cases in this specification that are still under discussion. [RFC1323] RFC 2873 S: "TCP Processing of the IPv4 Precendence Field" (Jun 00) This document removes from the TCP specification all processing of the precedence bits of the TOS byte of the IP header. This resolves a conflict between RFC 793 and Diff-Serv. [RFC2873] RFC 2988 S: "Computing TCP's Retransmission Timer" (Nov 00) Abstract: "This document defines the standard algorithm that Transmission Control Protocol (TCP) senders are required to use to compute and manage their retransmission timer. It expands on the discussion in section 4.2.3.1 of RFC 1122 and upgrades the requirement of supporting the algorithm from a SHOULD to a MUST." [RFC2988] 2.2 Congestion Control RFC 2581 S: "TCP Congestion Control" (Apr 99) This document defines the current versions of Van Jacobson's congestion avoidance and control mechanisms for TCP, based on his 1988 SIGCOMM paper [vj88]. [RFC2581] RFC 3042 S: "Enhancing TCP's Loss Recovery Using Limited Transmit" (Jan 01) Abstract: "This document proposes a new Transmission Control Protocol (TCP) mechanism that can be used to more effectively recover lost segments when a connection's congestion window is small, or when a large number of segments are lost in a single transmission window." [RFC3042] RFC 3168 S: "The Addition of Explicit Congestion Notification (ECN) to IP" (Sep 01) This document defines a means of detecting congestion without resorting to loss. Although congestion notification takes place Duke, et al. Expires April 8, 2005 [Page 6] Internet-Draft TCP Roadmap October 2004 at the IP level, support is required at the transport level to echo the bits and adapt the sending rate. This document updates RFC 793 to define two previously-unused flag bits in the TCP header. [RFC3168] RFC 3390 S: "Increasing TCP'S Initial Window" (Oct 02) This document permits a TCP to use an initial window larger that one packet during in the slow-start phase, updating RFC 2581. [RFC3390] RFC 3782 S: "The NewReno Modification to TCP's Fast Recovery Algorithm" (Apr 04) This document specifies a slight modification to the standard Reno fast recovery algorithm, whereby a TCP sender can use partial acknowledgements to make inferences determining the next segment to send in situations where SACK would be helpful, but isn't available. [RFC3782] 2.3 SACK-based Loss Recovery RFC 2018 S: "TCP Selective Acknowledgement Options" (Oct 96) This document defines the sective acknowledgement (SACK) mechanism, providing more fine-grained acknowledgement information than the basic cummulative acknowledgement mechanism. Exchange of SACK information is widely implemented in modern operating systems. [RFC2018] RFC 2883 S: "An Extension to the Selective Acknowledgement (SACK) Option for TCP" (Jul 00) This document extends RFC 2018 to cover the case of acknowledging duplicate packets. [RFC2883] RFC 3517 S: "A Conservative Selective Acknowledgement (SACK)-based Loss Recovery Algorithm for TCP" (Apr 03) This document describes a TCP loss recovery algorithm which uses available SACK information to intelligently recover when more than one segment is lost from a single flight of data. While support for the exchange of SACK information is widely implemented, not all implementations use an algorithm as sophisticated as that described in RFC 3517. [RFC3517] Duke, et al. Expires April 8, 2005 [Page 7] Internet-Draft TCP Roadmap October 2004 2.4 TCP MIBs The first MIB module defined for use with SNMP (in RFC 1066 and its update, RFC 1156) was a single monolithic MIB module, called MIB-I. This evolved over time to be MIB-II (RFC 1213). It then became apparent that having a single monolithic MIB module was not scalable, given the number and breadth of MIB data definitions that needed to be included. Thus, additional MIB modules were defined, and those parts of MIB-II which needed to evolve were split off. Eventually, the remaining parts of MIB-II were also split off, with the TCP-specific part being documented in RFC 2012. RFC 2012 is the primary document that implementers should presently be concerned with for MIB-II. If implementers desire to support MIB-I, then RFC 1156 is the document to refer to, although it has been obsoleted by the MIB-II specification in RFC 1213. Although a standards track document, RFC 2452 is considered a historic mistake by the MIB community, as it is based on the idea of parallel IPv4 and IPv6 structures. The community has decided that while new structures are needed to accomodate IPv6, a single generic structure for both IPv4 and IPv6 addresses, to aid in definition, implementation, and transition between IPv4 and IPv6. RFC 1156 S: "Management Information Base for Network Management of TCP/IP-based Internets" (May 90) This document describes the required MIB fields for TCP implementations, with minor corrections and no technical changes from RFC 1066, which it obsoletes. This is the standards track document for MIB-I. [RFC1156] RFC 2012 S: "SNMPv2 Management Information Base for the Transmission Control Protocol using SMIv2" (Nov 96) This document defines the TCP MIB, updating RFC 1213.[RFC2012] RFC 2452 S: "IP Version 6 Management Information Base for the Transmission Control Protocol" (Dec 98) This document augments RFC 2012 by adding an IPv6-specific connection table. The rest of 2012 holds for any IP version. ((Shouldn't 2452 "Update" 2012 ?)) [RFC2452] Duke, et al. Expires April 8, 2005 [Page 8] Internet-Draft TCP Roadmap October 2004 3. Special Cases and Implementation Hints RFC 1144 S: "Compressing TCP/IP headers for low-speed serial links" (Feb 90) This document contains Van Jacobson's classic specification of TCP/IP header compression. It is notable for its elegance and clarity. [RFC1144] RFC 1948 I: "Defending Against Sequence Number Attacks" (May 96) The sequence number guessing TCP vulnerability is described in this document and means for defending it from exploitation are discussed in this document. Some variation is implemented in most modern operating systems. [RFC1948] RFC 2140 I: "TCP Control Block Interdependence" (Apr 97) This document suggests how TCP connections between the same endpoints might share information, such as their congestion control state. To some degree, this is done in practice by a few modern operating systems. [RFC2140] RFC 2488 B: "Enhancing TCP Over Satellite Channels using Standard Mechanisms" (Jan 99) From abstract: "While TCP works over satellite channels there are several IETF standardized mechanisms that enable TCP to more effectively utilize the available capacity of the network path. This document outlines some of these TCP mitigations. At this time, all mitigations discussed in this document are IETF standards track mechanisms (or are compliant with IETF standards)." [RFC2488] RFC 2525 I: "Known TCP Implementation Problems" (Mar 99) From abstract: "This memo catalogs a number of known TCP implementation problems. The goal in doing so is to improve conditions in the existing Internet by enhancing the quality of current TCP/IP implementations." [RFC2525] RFC 3360 B: "Inappropriate TCP Resets Considered Harmful" (Aug 02) This document is a plea to firewall vendors not to send gratuitous TCP RST (Reset) packets when unassigned TCP header bits are used. This practice prevents desirable extension and evolution of the protocol and hence is inimical to the future of the Internet. [RFC3360] Duke, et al. Expires April 8, 2005 [Page 9] RFC 3449 B: "TCP Performance Implications of Network Path Asymmetry" (Dec 02) From abstract: "This document describes TCP performance problems that arise because of asymmetric effects. These problems arise in several access networks, including bandwidth-asymmetric networks and packet radio subnetworks, for different underlying reasons. However, the end result on TCP performance is the same in both cases: performance often degrades significantly because of imperfection and variability in the ACK feedback from the receiver to the sender. The document details several mitigations to these effects, which have either been proposed or evaluated in the literature, or are currently deployed in networks." [RFC3449] RFC 3481 B: "TCP over Second (2.5G) and Third (3G) Generation Wireless Networks" (Feb 03) From abstract: "This document describes a profile for optimizing TCP to adapt so that it handles paths including second (2.5G) and third (3G) generation wireless networks." [RFC3481] RFC 3493 I: "Basic Socket Interface Extensions for IPv6" (Feb 03) This document describes the de facto standard sockets API for programming with TCP, which is implemented nearly ubiquitously in modern operating systems and programming languages. [RFC3493] Duke, et al. Expires April 8, 2005 [Page 10] Internet-Draft TCP Roadmap October 2004 4. Experimental TCP Extensions These documents may one day join the standards track, but they are currently not recommended for implementation. RFC 2861 E: "TCP Congestion Window Validation" (Jun 00) Decaying the congestion window if it hasn't been recently utilized. [RFC2861] RFC 3465 E: "TCP Congestion Control with Appropriate Byte Counting (ABC)" (Feb 03) Congestion control using number of bytes acknowledged rather than number of acknowledgements received. Implemented in Linux. [RFC3465] RFC 3522 E: "The Eifel Detection Algorithm for TCP" (Apr 03) Use of timestamps to detect spurious timeouts. [RFC3522] RFC 3540 E: "Robust Explicit Congestion Notification (ECN) signaling with Nonces" (Jun 03) Modified ECN to address security concerns. [RFC3540] RFC 3649 E: "HighSpeed TCP for Large Congestion Windows" (Dec 03) A modification to TCP's steady state behavior in order to efficiently use very large windows is described in this document. RFC 3742 E: "Limited Slow-Start for TCP with Large Congestion Windows" (Mar 04) This document describes a more conservative slow-start behavoir to prevent massive amounts of loss when connections use very large windows. [RFC3742] Duke, et al. Expires April 8, 2005 [Page 11] Internet-Draft TCP Roadmap October 2004 5. Deprecated TCP Extensions The RFCs listed here define extensions that failed to arouse substantial interest, or were found to be defective. RFC 1146 E "TCP Alternate Checksum Options" (Mar 90) This document defined a mechanism for using TCP checksums other than the 16-bit ones-complement, which might be more robust. [RFC1146] RFC 1379 I "Extending TCP for Transactions -- Concepts" (Nov 92) See RFC 1644. [RFC1379] RFC 1644 E "T/TCP -- TCP Extensions for Transactions Functional Specification" (Jul 94) The inventors of T/TCP believed that cached connection state could be used to eliminate TCP's 3-way handshake, to support single- packet request/response exchanges. RFCs 1379 and 1644 show that it is far from simple. Furthermore, T/TCP floundered on the ease of denial-of-service attacks that can result. [RFC1644] RFC 1693 E "An Extension to TCP: Partial Order Service" (Nov 94) This document defines a TCP extension for applications where the order that application layer objects are received in is relatively unimportant, citing multimedia and database applications as examples. In practice, these applications either made due with the mismatch of standard TCP for their goals, or used other more specialized transport protocols. [RFC1693] Duke, et al. Expires April 8, 2005 [Page 12] Internet-Draft TCP Roadmap October 2004 6. Case Studies and Protocol Analysis RFC 1337 I: "TIME-WAIT Assassination Hazards in TCP" (May 92) This document points out a problem with acting on received reset segments while in the TIME-WAIT state. The main reccommendation is that hosts in TIME-WAIT ignore resets. [RFC1337] RFC 2415 I: "Simulation Studies of Increased Initial TCP Window Size" (Sep 98) Results of some simulations using TCP initial windows greater than 1 segment are presented in this document. The analysis indicates that user-perceived performance can be improved by increasing the initial window to 3 segments. [RFC2415] RFC 2416 I: "When TCP Starts Up With Four Packets Into Only Three Buffers" (Sep 98) This document uses simulation results to clear up some concerns about using an initial window of 4 segments when the network path has less provisioning. [RFC2416] RFC 2760 I: "Ongoing TCP Research Related to Satellites" (Feb 00) This document discusses the advantages and disadvantages of several different experimental means of improving TCP performance over long-delay or error-prone paths. These include: T/TCP, larger initial windows, byte counting, delayed acknowledgements, slow start thresholds, NewReno and SACK-based loss recovery, FACK [FACK], ECN, various corruption-detection mechanisms, congestion avoidance changes for fairness, use of multiple parallel flows, pacing, header compression, state sharing, and ACK congestion control, filtering, and reconstruction. [RFC2760] RFC 2884 I: "Performance Evaluation of Explicit Congestion Notification (ECN) in IP Networks" (Jul 00) This document describes experimental results that show some improvements to the performance of both short and long-lived connections due to ECN. [RFC2884] RFC 2914 B: "Congestion Control Principles" (Sep 00) The use of end-to-end congestion control for preventing congestion collapse and providing fairness to TCP is motivated by this document. [RFC2914] Duke, et al. Expires April 8, 2005 [Page 13] Internet-Draft TCP Roadmap October 2004 RFC 2923 I: "TCP Problems with Path MTU Discovery" (Sep 00) From abstract: "This memo catalogs several known Transmission Control Protocol (TCP) implementation problems dealing with Path Maximum Transmission Unit Discovery (PMTUD), including the long-standing black hole problem, stretch acknowlegements (ACKs) due to confusion between Maximum Segment Size (MSS) and segment size, and MSS advertisement based on PMTU." [RFC2923] RFC 2963 I: "A Rate Adaptive Shaper for Differentiated Services" (Oct 2000) This document describes how TCP performance can be improved in diffserv networks using rate adaptive shapers and color markers. [RFC2963] RFC 3135 I: "Performance Enhancing Proxies Intended to Mitigate Link-Related Degradations" (Jun 01) From abstract: "This document is a survey of Performance Enhancing Proxies (PEPs) often employed to improve degraded TCP performance caused by characteristics of specific link environments, for example, in satellite, wireless WAN, and wireless LAN environments. Different types of Performance Enhancing Proxies are described as well as the mechanisms used to improve performance." [RFC3135] Duke, et al. Expires April 8, 2005 [Page 14] Internet-Draft TCP Roadmap October 2004 7. Tools and Tutorials RFC 1180 I: "TCP/IP Tutorial" (Jan 91) This document is an extremely brief overview of the TCP/IP protocol suite as a whole. It gives some explanation as to how and where TCP fits in. [RFC1180] RFC 1470 I: "FYI on a Network Management Tool Catalog: Tools for Monitoring and Debugging TCP/IP Internets and Interconnected Devices" (Jun 93) A few of the tools that this document describes are still maintained and in use today, such as ttcp and tcpdump, however, many of the tools described do not related specifically to TCP and are no longer used or easily available. [RFC1470] RFC 2398 I: "Some Testing Tools for TCP Implementors" (Aug 98) A number of TCP packet generation and analysis tools are described in this document. While some of these tools are no longer readily available or widely used, for the most part they are still relevant and useable. [RFC2398] Duke, et al. Expires April 8, 2005 [Page 15] Internet-Draft TCP Roadmap October 2004 8. Historical The documents listed in this section contain information that is largely duplicated by the standards documents in Section 2, however some of them contain a greater depth of problem statement explanation, or other historical context. RFC 813: "Window and Acknowledgement Strategy in TCP" (July 82) This document contains an early discussion of Silly Window Syndrome and its avoidance, and motivates and describes the use of delayed acknowledgements. [RFC0813] RFC 817: "Modularity and Efficiency in Protocol Implementation" (July 82) The suggestions for implementation in this document are general and not TCP-specific, however they have been used to develop TCP implementations and describe some performance implications of the interactions between various layers in the Internet stack. [RFC0817] RFC 876: "The TCP Maximum Segment Size and Related Topics" (Nov 83) Abstract: This memo discusses the TCP Maximum Segment Size Option and related topics. The purposes is to clarify some aspects of TCP and its interaction with IP. This memo is a clarification to the TCP specification, and contains information that may be considered as "advice to implementers". [RFC0876] RFC 896: "Congestion Control in IP/TCP Internetworks" (Jan 84) This document contains some early experiences with congestion collapse and some initial thoughts on how to avoid it using congestion control in TCP. [RFC0896] RFC 964: "Some Problems with the Specification of the Military Standard Transmission Control Protocol" (Nov 85) The US Military wrote their own document defining TCP in addition to RFC 793. A few serious specification bugs are detailed in RFC 964, reminding us of the difficulty in specification writing (even when working from existing documents!). [RFC0964] RFC 1066: "Management Information Base for Network Management of TCP/IP-based Internets" (Aug 88) This was the first document describing the TCP MIB. It is Duke, et al. Expires April 8, 2005 [Page 16] Internet-Draft TCP Roadmap October 2004 obsoleted by RFC 1156. [RFC1066] RFC 1072: "TCP Extensions for Long-Delay Paths" (Oct 88) Early explanations of the mechanisms that were later described by RFCs 1323 and 2018 are found in this document. [RFC1072] RFC 1185: "TCP Extension for High-Speed Paths" (Oct 90) More advanced strategies for dealing with sequence number wrapping and detecting duplicates from earlier connections are outlined in this document that builds on RFC 1072. [RFC1185] RFC 1213 S: "Management Information Base for Network Management of TCP/IP-based Internets: MIB-II" (Mar 91) This document describes the second version of the MIB in a monolithic form. RFC 2012 updates this document, by splitting out the TCP-specific portions. [RFC1213] Duke, et al. Expires April 8, 2005 [Page 17] Internet-Draft TCP Roadmap October 2004 9. Security Considerations This document introduces no new security considerations. Each RFC listed in this document attempts to address the security considerations of the proposals it contains. Duke, et al. Expires April 8, 2005 [Page 18] Internet-Draft TCP Roadmap October 2004 10. Acknowledgments This document grew out of a discussion on the end2end-interest mailing list, the public list of the End-to-End Research Group of the IRTF. We thank Joe Touch and Reiner Ludwig for their contributions, in particular. The chairs of the TCPM working group, Mark Allman and Ted Faber, have been instrumental in the development of this document. Keith McCloghrie provided some useful notes and clarification on the various MIB-related RFCs. Duke, et al. Expires April 8, 2005 [Page 19] Internet-Draft TCP Roadmap October 2004 11. References 11.1 Core Specification [RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, September 1981. [RFC1122] Braden, R., "Requirements for Internet Hosts - Communication Layers", STD 3, RFC 1122, October 1989. [RFC1156] McCloghrie, K. and M. Rose, "Management Information Base for network management of TCP/IP-based internets", RFC 1156, May 1990. [RFC1323] Jacobson, V., Braden, B. and D. Borman, "TCP Extensions for High Performance", RFC 1323, May 1992. [RFC2012] McCloghrie, K., "SNMPv2 Management Information Base for the Transmission Control Protocol using SMIv2", RFC 2012, November 1996. [RFC2018] Mathis, M., Mahdavi, J., Floyd, S. and A. Romanow, "TCP Selective Acknowledgment Options", RFC 2018, October 1996. [RFC2452] Daniele, M., "IP Version 6 Management Information Base for the Transmission Control Protocol", RFC 2452, December 1998. [RFC2581] Allman, M., Paxson, V. and W. Stevens, "TCP Congestion Control", RFC 2581, April 1999. [RFC2873] Xiao, X., Hannan, A., Paxson, V. and E. Crabbe, "TCP Processing of the IPv4 Precedence Field", RFC 2873, June 2000. [RFC2883] Floyd, S., Mahdavi, J., Mathis, M. and M. Podolsky, "An Extension to the Selective Acknowledgement (SACK) Option for TCP", RFC 2883, July 2000. [RFC2988] Paxson, V. and M. Allman, "Computing TCP's Retransmission Timer", RFC 2988, November 2000. [RFC3042] Allman, M., Balakrishnan, H. and S. Floyd, "Enhancing TCP's Loss Recovery Using Limited Transmit", RFC 3042, January 2001. [RFC3168] Ramakrishnan, K., Floyd, S. and D. Black, "The Addition of Explicit Congestion Notification (ECN) to IP", RFC 3168, Duke, et al. Expires April 8, 2005 [Page 20] Internet-Draft TCP Roadmap October 2004 September 2001. [RFC3390] Allman, M., Floyd, S. and C. Partridge, "Increasing TCP's Initial Window", RFC 3390, October 2002. [RFC3517] Blanton, E., Allman, M., Fall, K. and L. Wang, "A Conservative Selective Acknowledgment (SACK)-based Loss Recovery Algorithm for TCP", RFC 3517, April 2003. [RFC3782] Floyd, S., Henderson, T. and A. Gurtov, "The NewReno Modification to TCP's Fast Recovery Algorithm", RFC 3782, April 2004. 11.2 Special Cases and Implementation Hints [RFC1144] Jacobson, V., "Compressing TCP/IP headers for low-speed serial links", RFC 1144, February 1990. [RFC1948] Bellovin, S., "Defending Against Sequence Number Attacks", RFC 1948, May 1996. [RFC2140] Touch, J., "TCP Control Block Interdependence", RFC 2140, April 1997. [RFC2488] Allman, M., Glover, D. and L. Sanchez, "Enhancing TCP Over Satellite Channels using Standard Mechanisms", BCP 28, RFC 2488, January 1999. [RFC2525] Paxson, V., Dawson, S., Fenner, W., Griner, J., Heavens, I., Lahey, K., Semke, J. and B. Volz, "Known TCP Implementation Problems", RFC 2525, March 1999. [RFC3360] Floyd, S., "Inappropriate TCP Resets Considered Harmful", BCP 60, RFC 3360, August 2002. [RFC3449] Balakrishnan, H., Padmanabhan, V., Fairhurst, G. and M. Sooriyabandara, "TCP Performance Implications of Network Path Asymmetry", BCP 69, RFC 3449, December 2002. [RFC3481] Inamura, H., Montenegro, G., Ludwig, R., Gurtov, A. and F. Khafizov, "TCP over Second (2.5G) and Third (3G) Generation Wireless Networks", BCP 71, RFC 3481, February 2003. [RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J. and W. Stevens, "Basic Socket Interface Extensions for IPv6", RFC 3493, February 2003. Duke, et al. Expires April 8, 2005 [Page 21] Internet-Draft TCP Roadmap October 2004 11.3 Experimental TCP Extensions [RFC2861] Handley, M., Padhye, J. and S. Floyd, "TCP Congestion Window Validation", RFC 2861, June 2000. [RFC3465] Allman, M., "TCP Congestion Control with Appropriate Byte Counting (ABC)", RFC 3465, February 2003. [RFC3522] Ludwig, R. and M. Meyer, "The Eifel Detection Algorithm for TCP", RFC 3522, April 2003. [RFC3540] Spring, N., Wetherall, D. and D. Ely, "Robust Explicit Congestion Notification (ECN) Signaling with Nonces", RFC 3540, June 2003. [RFC3649] Floyd, S., "HighSpeed TCP for Large Congestion Windows", RFC 3649, December 2003. [RFC3742] Floyd, S., "Limited Slow-Start for TCP with Large Congestion Windows", RFC 3742, March 2004. 11.4 Deprecated TCP Extensions [RFC1146] Zweig, J. and C. Partridge, "TCP alternate checksum options", RFC 1146, March 1990. [RFC1379] Braden, B., "Extending TCP for Transactions -- Concepts", RFC 1379, November 1992. [RFC1644] Braden, B., "T/TCP -- TCP Extensions for Transactions Functional Specification", RFC 1644, July 1994. [RFC1693] Connolly, T., Amer, P. and P. Conrad, "An Extension to TCP : Partial Order Service", RFC 1693, November 1994. 11.5 Case Studies and Protocol Analysis [RFC1337] Braden, B., "TIME-WAIT Assassination Hazards in TCP", RFC 1337, May 1992. [RFC2415] Poduri, K., "Simulation Studies of Increased Initial TCP Window Size", RFC 2415, September 1998. [RFC2416] Shepard, T. and C. Partridge, "When TCP Starts Up With Four Packets Into Only Three Buffers", RFC 2416, September 1998. [RFC2760] Allman, M., Dawkins, S., Glover, D., Griner, J., Tran, D., Duke, et al. Expires April 8, 2005 [Page 22] Internet-Draft TCP Roadmap October 2004 Henderson, T., Heidemann, J., Touch, J., Kruse, H., Ostermann, S., Scott, K. and J. Semke, "Ongoing TCP Research Related to Satellites", RFC 2760, February 2000. [RFC2884] Hadi Salim, J. and U. Ahmed, "Performance Evaluation of Explicit Congestion Notification (ECN) in IP Networks", RFC 2884, July 2000. [RFC2914] Floyd, S., "Congestion Control Principles", BCP 41, RFC 2914, September 2000. [RFC2923] Lahey, K., "TCP Problems with Path MTU Discovery", RFC 2923, September 2000. [RFC2963] Bonaventure, O. and S. De Cnodder, "A Rate Adaptive Shaper for Differentiated Services", RFC 2963, October 2000. [RFC3135] Border, J., Kojo, M., Griner, J., Montenegro, G. and Z. Shelby, "Performance Enhancing Proxies Intended to Mitigate Link-Related Degradations", RFC 3135, June 2001. 11.6 Tools and Tutorials [RFC1180] Socolofsky, T. and C. Kale, "TCP/IP tutorial", RFC 1180, January 1991. [RFC1470] Enger, R. and J. Reynolds, "FYI on a Network Management Tool Catalog: Tools for Monitoring and Debugging TCP/IP Internets and Interconnected Devices", RFC 1470, June 1993. [RFC2151] Kessler, G. and S. Shepard, "A Primer On Internet and TCP/IP Tools and Utilities", RFC 2151, June 1997. [RFC2398] Parker, S. and C. Schmechel, "Some Testing Tools for TCP Implementors", RFC 2398, August 1998. 11.7 Historical [RFC0813] Clark, D., "Window and Acknowledgement Strategy in TCP", RFC 813, July 1982. [RFC0817] Clark, D., "Modularity and efficiency in protocol implementation", RFC 817, July 1982. [RFC0876] Smallberg, D., "Survey of SMTP implementations", RFC 876, September 1983. Duke, et al. Expires April 8, 2005 [Page 23] Internet-Draft TCP Roadmap October 2004 [RFC0896] Nagle, J., "Congestion control in IP/TCP internetworks", RFC 896, January 1984. [RFC0964] Sidhu, D. and T. Blumer, "Some problems with the specification of the Military Standard Transmission Control Protocol", RFC 964, November 1985. [RFC1066] McCloghrie, K. and M. Rose, "Management Information Base for network management of TCP/IP-based internets", RFC 1066, August 1988. [RFC1072] Jacobson, V. and R. Braden, "TCP extensions for long-delay paths", RFC 1072, October 1988. [RFC1185] Jacobson, V., Braden, B. and L. Zhang, "TCP Extension for High-Speed Paths", RFC 1185, October 1990. [RFC1213] McCloghrie, K. and M. Rose, "Management Information Base for Network Management of TCP/IP-based internets:MIB-II", STD 17, RFC 1213, March 1991. 11.8 Informative References Ouside the RFC Series [FACK] Mathis, M. and J. Mahdavi, "Forward Acknowledgement: Refining TCP Congestion Control", ACM SIGCOMM, August 1996. [karn] Karn, P. and C. Partridge, "Round Trip Time Estimation", ACM SIGCOMM, August 1987. [vj88] Jacobson, V., "Congestion Avoidance and Control", ACM SIGCOMM, August 1988. Authors' Addresses Martin Duke Boeing Phantom Works PO Box 3707, MC 3W-51 Seattle, WA 98124-2207 Phone: 253-657-8203 EMail: mduke26@comcast.net Duke, et al. Expires April 8, 2005 [Page 24] Internet-Draft TCP Roadmap October 2004 Robert Braden USC Information Sciences Institute Marina del Rey, CA 90292-6695 Phone: 310-448-9173 EMail: braden@isi.edu Wesley M. Eddy NASA GRC/Verizon FNS EMail: weddy@grc.nasa.gov Ethan Blanton Purdue University EMail: eblanton@cs.purdue.edu Duke, et al. Expires April 8, 2005 [Page 25] Internet-Draft TCP Roadmap October 2004 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2004). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Duke, et al. Expires April 8, 2005 [Page 26]