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Versions: 00 01 02 03 04 05 06 RFC 4614

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
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   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




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   (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.















































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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




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   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.














































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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]







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   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




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      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]






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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]










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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]




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   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]




























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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]















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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]




















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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]





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   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]


























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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]































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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




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      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]

































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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.















































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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.











































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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,




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              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.





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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.,




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              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.





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   [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










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   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


































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