RFC 7414

A Roadmap for Transmission Control Protocol (TCP) Specification Documents

📅 published February 2015, from ietf

A Roadmap for Transmission Control Protocol (TCP) Specification Documents 🎀

okay bestie, this is RFC 7414 🦋 It's a roadmap to all the TCP RFCs, so you can find your way around the TCP docs without getting lost.

Here's the title block, sorted out:

Number: RFC 7414
Authors: M. Duke (F5), R. Braden (ISI), W. Eddy (MTI Systems), E. Blanton (Interrupt Sciences), and A. Zimmermann (NetApp, Inc.)
Category: Informational 💜 (not a Standards Track doc!)
ISSN: 2070-1721
Date: February 2015
Obsoletes: RFC 4614 🍓
Updates: nothing 🙈

Abstract ✨

okay so this doc is a roadmap to the Request for Comments (RFC) documents about the Internet's Transmission Control Protocol (TCP) 💖 It gives you a quick summary of the docs that define TCP and the TCP extensions that have piled up in the RFC series. It's a guide and quick reference for TCP implementers, plus anyone else who wants info from the TCP-related RFCs. main character energy 💅

This document obsoletes RFC 4614.

Status of This Memo 🌸

so this is not an Internet Standards Track spec. It's published for information only 🧚

It's still a product of the Internet Engineering Task Force (IETF) 👑 It represents the consensus of the IETF community, got public review, and was approved for publication by the Internet Engineering Steering Group (IESG). ngl that's a lot of approval 😭 BUT not every IESG-approved doc is a candidate for any level of Internet Standard. See Section 2 of RFC 5741 for that.

For the current status of this doc, any errata, and how to give feedback, check http://www.rfc-editor.org/info/rfc7414 🌈

Copyright Notice 🫶

This doc is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) as they were on the publication date. Please read these carefully, because they explain your rights and restrictions for this doc. Code Components taken from this doc must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions, and they come without warranty as described in the Simplified BSD License. ✨

Table of Contents 🧚

   1. Introduction ....................................................4
   2. Core Functionality ..............................................6
   3. Strongly Encouraged Enhancements ................................8
      3.1. Fundamental Changes ........................................9
      3.2. Congestion Control Extensions .............................10
      3.3. Loss Recovery Extensions ..................................11
      3.4. Detection and Prevention of Spurious Retransmissions ......13
      3.5. Path MTU Discovery ........................................14
      3.6. Header Compression ........................................15
      3.7. Defending Spoofing and Flooding Attacks ...................15
   4. Experimental Extensions ........................................17
      4.1. Architectural Guidelines ..................................18
      4.2. Fundamental Changes .......................................18
      4.3. Congestion Control Extensions .............................19
      4.4. Loss Recovery Extensions ..................................20
      4.5. Detection and Prevention of Spurious Retransmissions ......21
      4.6. TCP Timeouts ..............................................22
      4.7. Multipath TCP .............................................22
   5. TCP Parameters at IANA .........................................23
   6. Historic and Undeployed Extensions .............................24
   7. Support Documents ..............................................27
      7.1. Foundational Works ........................................27
      7.2. Architectural Guidelines ..................................29
      7.3. Difficult Network Environments ............................30
      7.4. Guidance for Developing, Analyzing, and Evaluating TCP ....33
      7.5. Implementation Advice .....................................34
      7.6. Tools and Tutorials .......................................36
      7.7. MIB Modules ...............................................37
      7.8. Case Studies ..............................................39
   8. Undocumented TCP Features ......................................40
   9. Security Considerations ........................................41
   10. References ....................................................42
      10.1. Normative References .....................................42
      10.2. Informative References ...................................53
   Acknowledgments ...................................................56
   Authors' Addresses ................................................57

1. Introduction 💖

okay so a correct, efficient TCP implementation is a critical part of the software on most Internet hosts 🔥 TCP has evolved over the years, and a bunch of distinct docs have become the accepted standard for it. At the same time, tons of experimental TCP changes have been published in the RFC series, along with informational notes, case studies, and other advice. it's a LOT 😭

So this doc is here to help newcomers get started and to organize all that info for the old hands 🎀 It gives a brief summary of the RFCs that define TCP and should guide implementers on how relevant and significant the standards-track extensions, informational notes, and best current practices are.

This doc is not an update of RFC 1122 [RFC1122], and it is not a rigorous standard for what TCP has to implement 🙈 It's just an informational roadmap that captures, organizes, and summarizes most of the RFCs that a TCP implementer, experimenter, or student should know about. Any comments or broad categories it makes about specific mechanisms and behaviors are not definitive, and the content of this doc alone should not be what drives implementation decisions 🫶

Each TCP-related RFC gets a short description. Sometimes we just copy the abstract or a key summary sentence as a quick blurb ✨ Also, a letter code after an RFC number tells you its category in the RFC series (see BCP 9 [RFC2026] for the explanation of these categories):

S - Standards Track (Proposed Standard, Draft Standard, or Internet Standard) 👑
E - Experimental 🧪
I - Informational 🌸
H - Historic 🕰️
B - Best Current Practice 💅
U - Unknown (not formally defined) 🌈

Here's the vibe check: the category of an RFC doesn't always match how relevant it is today 💀 For example, RFC 5681 [RFC5681] is considered part of the required core functionality of TCP, even though it's only a Draft Standard. Same deal with some Informational RFCs, which can have big technical proposals for changing TCP. Iconic behavior 💖

Last thing: if an error in the technical content was found after an RFC was published (as of when this was written), the headline of that RFC's description says "(Errata)". You can find the errata through the RFC Errata page [Errata] 🦋

This roadmap has three main sections. Section 2 lists the RFCs that describe absolutely required TCP behaviors for proper functioning and interoperability. Strongly encouraged, but nonessential, behaviors are in Section 3. Experimental extensions that aren't standard practice yet, but could be someday, are in Section 4 🔮

Here's the thing the reader will probably notice: these three sections basically line up with MUST/SHOULD/MAY specs (per RFC 2119 [RFC2119]). The authors agree with that intuition, but this doc is only descriptive. It is not a binding Standards Track position. Individual implementers still need to read the Standards Track RFCs themselves to figure out the specific requirement levels 📖

Section 5 covers the procedures that the Internet Assigned Numbers Authority (IANA) follows, and that an RFC author should follow, when new TCP parameters get requested and finally assigned 🧚

A few older experimental extensions that never got widely implemented, deployed, or used are noted in Section 6. Lots of other supporting docs that matter for developing, implementing, and deploying TCP are in Section 7 💜

A small set of pretty ubiquitous implementation practices that aren't documented in the RFC series yet are listed in Section 8 🌟

And within each section, the RFCs are listed in chronological order of their publication dates. Time to dive into Section 2 🎀✨

2. Core Functionality ✨

okay bestie, TCP's core spec is a small squad of documents 🫶 they define the required basics: header parsing, the state machine, congestion control, and how retransmission timeouts get computed. if you want interop with anyone, you have to follow these correctly. no skipping 💅

`RFC 793 S: "Transmission Control Protocol", STD 7 (September 1981) (Errata)`

this is the OG TCP spec [RFC793] 👑 Jon Postel wrote it as part of the core Internet protocol suite. it covers the TCP packet format, the state machine and event processing, and TCP's semantics for data transmission, reliability, flow control, multiplexing, and acknowledgment. iconic. 🦋

ok but Section 3.6 of RFC 793, the bit about IP precedence and the security compartment, is mostly irrelevant now 🙈 RFC 2873 (we'll get to it below in Section 2) changed the IP precedence handling, and the security compartment part of the API isn't implemented or used anymore. also, RFC 793 didn't describe any congestion control mechanism, which is kinda wild lol. still, most of this doc is totally accurate for modern TCPs 💖 RFC 793 is the last in a series of developmental TCP specs that started in the Internet Experimental Notes (IENs) and kept going in the RFC series. main character origin story 🌈

`RFC 1122 S: "Requirements for Internet Hosts - Communication Layers" (October 1989)`

this one [RFC1122] updates and clarifies RFC 793 (see above in Section 2) and fixes some spec bugs and oversights 🔧 it also explains stuff like keep-alives and Karn's and Jacobson's RTO estimation algorithms [KP87][Jac88][JK92], mentions ICMP interactions, and gives some tips for efficient implementation 🍓

the vibe check: RFC 1122 is an Applicability Statement, listing the features that a conforming TCP implementation MUST, SHOULD, MAY, SHOULD NOT, and MUST NOT have. unlike a purely informational roadmap, this one is a standards document with formal rules for implementation. no vibes-only, it's the real deal 💅

`RFC 2460 S: "Internet Protocol, Version 6 (IPv6) Specification" (December 1998) (Errata)`

this doc [RFC2460] matters for TCP because it defines how the pseudo-header for TCP's checksum gets derived when you're using 128-bit IPv6 addresses instead of 32-bit IPv4 ones 🌸 also, RFC 2675 (see Section 3.1 of this document) describes the TCP changes needed to support IPv6 jumbograms. 🧚

`RFC 2873 S: "TCP Processing of the IPv4 Precedence Field" (June 2000) (Errata)`

this doc [RFC2873] removes all processing of the precedence bits in the TOS byte of the IP header from the TCP spec 🙌 it resolves a clash over those bits between RFC 793 (see above in Section 2) and Differentiated Services [RFC2474]. two specs fighting over one field? not it. 💀

`RFC 5681 S: "TCP Congestion Control" (August 2009)`

so RFC 793 (see above in Section 2) had no congestion control, but today it's a required part of TCP implementations 😭 this doc [RFC5681] defines the congestion avoidance and control mechanisms for TCP, based on Van Jacobson's 1988 SIGCOMM paper [Jac88]. legendary. 👑

the behaviors that the community calls "Reno TCP" are described in RFC 5681 ✨ the name "Reno" comes from the Net/2 release of the 4.3 BSD operating system. it's generally considered the least common denominator among TCP flavors running on Internet hosts, and it includes slow start, congestion avoidance, fast retransmit, and fast recovery. the classics, fr fr 🫶

RFC 5681 details the currently accepted congestion control mechanism, while RFC 1122 (see above in Section 2) says such a mechanism must be implemented. RFC 5681 is a little different from the other docs in this section, because it doesn't affect whether two TCP endpoints can talk to each other 💜 but congestion control is still critical in any widely deployed TCP, it's required to avoid congestion collapse, and it keeps flows fair to each other. it's giving teamwork 🌈

RFCs 2001 and 2581 are the conceptual precursors of RFC 5681. the biggest changes from RFC 2581 are:

(a) the initial window requirements were changed to allow larger Initial Windows, as standardized in [RFC3390] (see Section 3.2 of this document).
(b) during slow start and congestion avoidance, the use of Appropriate Byte Counting [RFC3465] (see Section 3.2 of this document) is explicitly recommended.
(c) the use of Limited Transmit [RFC3042] (see Section 3.3 of this document) is now recommended.

`RFC 6093 S: "On the Implementation of the TCP Urgent Mechanism" (January 2011)`

this doc [RFC6093] looks at how current TCP stacks process urgent indications, and how widely deployed middleboxes affect that processing 👀 it updates the relevant specs so they match current practice, and it raises awareness that TCP urgent indications aren't very reliable across the Internet. it recommends against using the urgent mechanism. ngl, that's a strong take 💀🍓

`RFC 6298 S: "Computing TCP's Retransmission Timer" (June 2011)`

the abstract of RFC 6298 [RFC6298] says: "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."

and RFC 6298 updates RFC 2988 by changing the initial RTO from 3s to 1s ⏱️✨

`RFC 6691 I: "TCP Options and Maximum Segment Size (MSS)" (July 2012)`

this doc [RFC6691] clarifies what value to use with the TCP Maximum Segment Size (MSS) option when IP and TCP options are in use 🎀

3. Strongly Encouraged Enhancements 🔥

this section is full of recommended TCP changes that improve performance and security 💖 Section 3.1 covers fundamental changes to the protocol. Sections 3.2 and 3.3 list improvements to the congestion control and loss recovery mechanisms specified in RFC 5681 (see Section 2). Section 3.4 describes algorithms that let a TCP sender detect whether it has entered loss recovery spuriously.

Section 3.5 covers Path MTU Discovery mechanisms. Schemes for TCP/IP header compression are listed in Section 3.6. And Section 3.7 deals with preventing acceptance of forged segments and flooding attacks 🛡️

3.1. Fundamental Changes

okay so RFCs 2675 and 7323 are fundamental changes to TCP, because they redefine how parts of the basic TCP header and options get interpreted 🦋 RFC 7323 defines the Window Scale option, which reinterprets the advertised receive window. RFC 2675 says the MSS option and urgent pointer fields with a value of 65,535 are to be treated specially. the way that these change the basics 😭

`RFC 2675 S: "IPv6 Jumbograms" (August 1999) (Errata)`

IPv6 supports longer datagrams than IPv4 ever did 🚀 these are called jumbograms, and using them with TCP means the handling of TCP's MSS and Urgent fields (both 16 bits) had to change. this doc [RFC2675] explains those changes. even though it changes basic header semantics, these changes should only affect very large segments, like IPv6 jumbograms, which are rarely used on the general Internet right now 🌸

supporting this behavior doesn't affect interoperability with other TCP implementations when IPv4 or non-jumbogram IPv6 is used, which is a relief 🫶 the doc says jumbograms are only to be used when it can be guaranteed that every receiving node, including each router in the end-to-end path, will support jumbograms. if even one node that doesn't support jumbograms is attached to a local network, then no host on that network may use jumbograms. that's why jumbogram use has been rare, and why this doc is treated as a performance optimization and not part of TCP over IPv6's basic functionality 💅

`RFC 7323 S: "TCP Extensions for High Performance" (September 2014)`

this doc [RFC7323] defines TCP extensions for window scaling, timestamps, and protection against wrapped sequence numbers, so things run efficiently and safely over paths with large bandwidth-delay products 🌈 these extensions are commonly found in systems in use today. its predecessor, RFC 1323, was published in 1992 and is deployed in most TCP implementations. this doc includes fixes and clarifications based on deployment experience, and one specific issue it addresses is a recommendation on how to modify the algorithm for estimating the mean RTT when timestamps are used ⏱️ RFCs 1072, 1185, and 1323 are the conceptual precursors of RFC 7323 ✨

3.2. Congestion Control Extensions 💖

okay bestie, TCP's two biggest vibes are congestion control and loss recovery 🌸 TCP treats a lost packet as a sign of congestion, but it can't tell congestion-related loss apart from loss caused by transmission errors 🙈 even when ECN is in use, congestion control and loss recovery are basically joined at the hip 🫶 a lot of extensions touch both sides, and more often than not one extension hits both. so in these two subsections we group the glow-ups for congestion control, and the next subsection focuses on loss recovery ✨

RFC 3168 S: "The Addition of Explicit Congestion Notification (ECN) to IP" (September 2001)

this doc [RFC3168] lets end hosts detect congestion before congested routers are forced to discard packets 🦋 congestion notification happens at the IP level, but ECN needs transport-level support (like in TCP) to echo the bits and adapt the sending rate 💅 this doc updates RFC 793 (see Section 2 of this document) to define two previously unused flag bits in the TCP header for ECN support. RFC 3540 (see Section 4.3 of this document) gives a supplementary (experimental) way to use ECN more securely 🔐 and RFC 2884 (see Section 7.8 of this document) shares some sample results from using ECN 📊

RFC 3390 S: "Increasing TCP's Initial Window" (October 2002)

this doc [RFC3390] specifies an increase in the permitted initial window for TCP, from one segment to three or four segments during the slow start phase, depending on the segment size 🚀

RFC 3465 E: "TCP Congestion Control with Appropriate Byte Counting (ABC)" (February 2003)

this doc [RFC3465] suggests that congestion control use the number of bytes acknowledged instead of the number of acknowledgments received 🧁 this glow-up helps TCP perform better when there's no one-to-one relationship between data segments and acknowledgments (like with delayed ACKs or ACK loss), and it closes a security hole that TCP receivers could use to trick the sender into raising its sending rate too fast (ACK-division [SCWA99] [RFC3449]) 🙅‍♀️ ABC is recommended by RFC 5681 (see Section 2 of this document) 🌈

RFC 6633 S: "Deprecation of ICMP Source Quench Messages" (May 2012)

this doc [RFC6633] formally deprecates the use of ICMP Source Quench messages by transport protocols, and recommends against the implementation of [RFC1016] 🪦 bye bye, Source Quench 👋

3.3. Loss Recovery Extensions 🩹

okay so for the typical implementation of the TCP fast recovery algorithm described in RFC 5681 (see Section 2 of this document), a TCP sender only retransmits a segment after a retransmit timeout (RTO) has occurred, or after three duplicate ACKs have arrived and triggered the fast retransmit 😩 a single RTO might lead to retransmitting several segments, while the fast retransmit algorithm in RFC 5681 only leads to a single retransmission. so multiple losses from one window of data can drag down performance 📉 the documents in this section are here to level up TCP's standard loss recovery algorithms, and some of them help TCP senders recover much better when multiple segments are lost from a single flight of data 💪

RFC 2018 S: "TCP Selective Acknowledgment Options" (October 1996) (Errata)

when more than one packet is lost during one RTT, TCP can struggle, because a TCP sender can only learn about one lost packet per RTT from cumulative acknowledgments 😵‍💫 this doc [RFC2018] defines the basic selective acknowledgment (SACK) mechanism for TCP, which helps get past those limits 🙌 the receiving TCP returns SACK blocks to tell the sender what data it has received, so the sender can retransmit only the missing data segments 🎯

RFC 3042 S: "Enhancing TCP's Loss Recovery Using Limited Transmit" (January 2001)

Abstract of RFC 3042 [RFC3042]: "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."

the algorithm described in RFC 3042 is called "Limited Transmit" 🍓 tests from 2004 showed that Limited Transmit was deployed in roughly one third of the web servers tested [MAF04] 👀 Limited Transmit is recommended by RFC 5681 (see Section 2 of this document) ✨

RFC 6582 S: "The NewReno Modification to TCP's Fast Recovery Algorithm" (April 2012)

this doc [RFC6582] specifies a modification to the standard Reno fast recovery algorithm. a TCP sender can use partial acknowledgments to figure out the next segment to send in situations where SACK would be helpful but isn't available 🧩 it's only a slight tweak, but NewReno can make a significant difference in performance when multiple segments are lost from a single window of data 🔥

RFCs 2582 and 3782 are the conceptual precursors of RFC 6582 🌱 the main change in RFC 3782 relative to RFC 2582 was to specify the Careful variant of NewReno's Fast Retransmit and Fast Recovery algorithms, and to advance those two algorithms from Experimental to Standards Track status 🎓 the main change in RFC 6582 relative to RFC 3782 was to solve a performance degradation that could occur if FlightSize on Full ACK reception is zero 🛠️

RFC 6675 S: "A Conservative Loss Recovery Algorithm Based on Selective Acknowledgment (SACK) for TCP" (August 2012)

this doc [RFC6675] describes a conservative loss recovery algorithm for TCP, based on the selective acknowledgment (SACK) TCP option [RFC2018] (see above in Section 3.3) 🫧 it conforms to the spirit of the congestion control specification in RFC 5681 (see Section 2 of this document), but lets TCP senders recover more effectively when multiple segments are lost from a single flight of data 💖

RFC 6675 is a revision of RFC 3517 that addresses several situations which weren't handled explicitly before 🧠 in particular:

(a) it improves loss detection in the event that the sender has outstanding segments that are smaller than Sender Maximum Segment Size (SMSS).
(b) it modifies the definition of a "duplicate acknowledgment" to utilize the SACK information in detecting loss.
(c) it maintains the ACK clock under certain circumstances involving loss at the end of the window.

3.4. Detection and Prevention of Spurious Retransmissions 🕵️‍♀️

okay the vibe check: spurious retransmission timeouts are harmful to TCP performance 😤 multiple algorithms have been defined for detecting when spurious retransmissions have occurred, but they respond differently when it comes to recovering performance 🎭 the IETF defined multiple algorithms because there are trade-offs in whether certain TCP options need to be implemented, plus concerns about IPR status ⚖️ the Standards Track RFCs in this section are closely related to the Experimental RFCs in Section 4.5, which also address this topic 🦋

RFC 2883 S: "An Extension to the Selective Acknowledgement (SACK) Option for TCP" (July 2000)

this doc [RFC2883] extends RFC 2018 (see Section 3.3 of this document) 🌷 it lets the SACK option acknowledge duplicate packets. with this extension, called DSACK, the sender can infer the order of packets received at the receiver, and therefore infer when it has unnecessarily retransmitted a packet 🕵️ a TCP sender can then use that info to detect spurious retransmissions (see [RFC3708]) ✅

RFC 4015 E: "The Eifel Response Algorithm for TCP" (February 2005)

this doc [RFC4015] describes the response portion of the Eifel algorithm 🪄 it can be used together with one of several methods for detecting when loss recovery has been spuriously entered, such as the Eifel detection algorithm in RFC 3522 (see Section 4.5), the algorithm in RFC 3708 (see Section 4.5 of this document), or F-RTO in RFC 5682 (see below in Section 3.4) 🔍

Abstract of RFC 4015 [RFC4015]: "Based on an appropriate detection algorithm, the Eifel response algorithm provides a way for a TCP sender to respond to a detected spurious timeout. It adapts the retransmission timer to avoid further spurious timeouts and (depending on the detection algorithm) can avoid the often unnecessary go-back-N retransmits that would otherwise be sent. In addition, the Eifel response algorithm restores the congestion control state in such a way that packet bursts are avoided."

RFC 5682 S: "Forward RTO-Recovery (F-RTO): An Algorithm for Detecting Spurious Retransmission Timeouts with TCP" (September 2009)

the F-RTO detection algorithm [RFC5682], originally described in RFC 4138, gives you an option for inferring spurious retransmission timeouts 🌟 unlike some similar detection methods (like RFCs 3522 and 3708, both listed in Section 4.5 of this document), F-RTO doesn't rely on any TCP options at all 🙌 the basic idea is to send previously unsent data after the first retransmission following an RTO. if the ACKs advance the window, the RTO may be declared spurious 🧚

3.5. Path MTU Discovery 🧚

okay so the MTUs on different links and tunnels across the Internet can vary WILDLY 😭 Fragmenting any packet that's bigger than the supported MTU on a hop is undesirable, so nobody wants that. TCP is the segmentation layer that chops an application's byte stream into IP packet payloads, so TCP implementations usually include Path MTU Discovery (PMTUD) mechanisms to maximize the size of the segments they send, without causing fragmentation inside the network. Some algorithms may use signaling from routers on the path to figure out that the MTU on some part of the path has been exceeded. the way that's giving careful planning 💅

RFC 1191 S: "Path MTU Discovery" (November 1990)

Abstract of RFC 1191 [RFC1191]: "This memo describes a technique for dynamically discovering the maximum transmission unit (MTU) of an arbitrary internet path. It specifies a small change to the way routers generate one type of ICMP message. For a path that passes through a router that has not been so changed, this technique might not discover the correct Path MTU, but it will always choose a Path MTU as accurate as, and in many cases more accurate than, the Path MTU that would be chosen by current practice."

RFC 1981 S: "Path MTU Discovery for IP version 6" (August 1996)

Abstract of RFC 1981 [RFC1981]: "This document describes Path MTU Discovery for IP version 6. It is largely derived from RFC 1191, which describes Path MTU Discovery for IP version 4."

RFC 4821 S: "Packetization Layer Path MTU Discovery" (March 2007)

Abstract of RFC 4821 [RFC4821]: "This document describes a robust method for Path MTU Discovery (PMTUD) that relies on TCP or some other Packetization Layer to probe an Internet path with progressively larger packets. This method is described as an extension to RFC 1191 and RFC 1981, which specify ICMP-based Path MTU Discovery for IP versions 4 and 6, respectively."

3.6. Header Compression 🎀

ngl, especially in streaming apps, TCP/IP headers can add up to more than 50% of the total amount of data sent 💀 That's totally fine on wired LANs where capacity is usually not the problem, but it's excessive for WANs and wireless systems where bandwidth is scarce. Header compression schemes for TCP/IP, like RObust Header Compression (ROHC), can seriously shrink that overhead. It performs really well over links with significant error rates and long round-trip times ✨

RFC 1144 S: "Compressing TCP/IP Headers for Low-Speed Serial Links" (February 1990)

This document [RFC1144] describes a method for compressing the headers of TCP/IP datagrams to improve performance over low-speed serial links. The method described in this document is limited in its handling of TCP options and cannot compress the headers of SYNs and FINs.

RFC 6846 S: "RObust Header Compression (ROHC): A Profile for TCP/IP (ROHC-TCP)" (January 2013)

From the Abstract of RFC 6846 [RFC6846]: "This document specifies a RObust Header Compression (ROHC) profile for compression of TCP/IP packets. The profile, called ROHC-TCP, provides efficient and robust compression of TCP headers, including frequently used TCP options such as selective acknowledgments (SACKs) and Timestamps."

RFC 6846 is the successor of RFC 4996. It fixes a technical issue with the SACK compression and clarifies other compression methods used.

3.7. Defending Spoofing and Flooding Attacks 🛡️💜

okay this one is serious bestie 😭 By default, TCP has no cryptographic structures to tell legitimate segments apart from ones spoofed by malicious hosts. Spoofing valid segments means correctly guessing a bunch of fields. The documents in this subsection describe ways to make that guessing harder, or to stop it from negatively affecting a connection.

RFC 4953 I: "Defending TCP Against Spoofing Attacks" (July 2007)

This document [RFC4953] discusses the recently increased vulnerability of long-lived TCP connections, such as BGP connections, to reset (send RST) spoofing attacks. The document analyzes the vulnerability, discussing proposed solutions at the transport level and their inherent challenges, as well as existing network level solutions and the feasibility of their deployment.

RFC 5461 I: "TCP's Reaction to Soft Errors" (February 2009)

This document [RFC5461] describes a nonstandard but widely implemented modification to TCP's handling of ICMP soft error messages that rejects pending connection-requests when such error messages are received. This behavior reduces the likelihood of long delays between connection-establishment attempts that may arise in some scenarios.

RFC 4987 I: "TCP SYN Flooding Attacks and Common Mitigations" (August 2007)

This document [RFC4987] describes the well-known TCP SYN flooding attack. It analyzes and discusses various countermeasures against these attacks, including their use and trade-offs.

RFC 5925 S: "The TCP Authentication Option" (June 2010)

This document [RFC5925] describes the TCP Authentication Option (TCP-AO), which is used to authenticate TCP segments. TCP-AO obsoletes the TCP MD5 Signature option of RFC 2385. It supports the use of stronger hash functions, protects against replays for long-lived TCP connections (as used, e.g., in BGP and LDP), coordinates key exchanges between endpoints, and provides a more explicit recommendation for external key management. Cryptographic algorithms for TCP-AO are defined in [RFC5926] (see below in Section 3.7).

RFC 5926 S: "Cryptographic Algorithms for the TCP Authentication Option (TCP-AO)" (June 2010)

This document [RFC5926] specifies the algorithms and attributes that can be used in TCP Authentication Option's (TCP-AO) [RFC5925] (see above in Section 3.7) current manual keying mechanism and provides the interface for future message authentication codes (MACs).

RFC 5927 I: "ICMP Attacks against TCP" (July 2010)

Abstract of RFC 5927 [RFC5927]: "This document discusses the use of the Internet Control Message Protocol (ICMP) to perform a variety of attacks against the Transmission Control Protocol (TCP). Additionally, this document describes a number of widely implemented modifications to TCP's handling of ICMP error messages that help to mitigate these issues."

RFC 5961 S: "Improving TCP's Robustness to Blind In-Window Attacks" (August 2010)

This document [RFC5961] describes minor modifications to how TCP handles inbound segments. This renders TCP connections, especially long-lived connections such as H-323 or BGP, less vulnerable to spoofed packet injection attacks where the 4-tuple (the source and destination IP addresses and the source and destination ports) has been guessed.

RFC 6528 S: "Defending against Sequence Number Attacks" (February 2012)

Abstract of RFC 6528 [RFC6528]: "This document specifies an algorithm for the generation of TCP Initial Sequence Numbers (ISNs), such that the chances of an off-path attacker guessing the sequence numbers in use by a target connection are reduced. This document revises (and formally obsoletes) RFC 1948, and takes the ISN generation algorithm originally proposed in that document to Standards Track, formally updating RFC 793"

4. Experimental Extensions 🧪✨

okay so the RFCs in this section are either Experimental and may become Proposed Standards later, or they're Proposed Standards (or Informational) that can be considered experimental because they aren't widely deployed yet 🦋 At least part of the reason they're still experimental is to get more wide-scale experience with them before a standards track decision is made.

If the Experimental RFC is a proposal for a new protocol capability or service, i.e., it requires a new TCP option code point, the implementation and experimentation should follow [RFC6994] (see Section 5 of this document), which describes how the experimental TCP option code points can concurrently support multiple TCP extensions.

By their publication as Experimental RFCs, it's hoped that the community of TCP researchers will analyze and test the contents of these RFCs 🔬 Experimentation is encouraged, but there is not yet formal consensus that these are fully logical and safe behaviors. Wide-scale deployment of implementations that use these features should be well thought out in terms of consequences 🫶

4.1. Architectural Guidelines 🌸

as multiple flows may share the same paths, sections of paths, or other resources, the TCP implementation may benefit from sharing information across TCP connections or other flows. Some experimental proposals have been documented, and some implementations have included the concepts.

RFC 2140 I: "TCP Control Block Interdependence" (April 1997)

This document [RFC2140] 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 operating systems; for example, Linux currently has a destination cache. Although this RFC is technically Informational, the concepts it describes are in experimental use, so we include it in this section.

RFC 3124 S: "The Congestion Manager" (June 2001)

This document [RFC3124] is a related proposal to RFC 2140 (see above in Section 4.1). The idea behind the Congestion Manager, moving congestion control outside of individual TCP connections, represents a modification to the core of TCP, which supports sharing information among TCP connections. Although a Proposed Standard, some pieces of the Congestion Manager support architecture have not been specified yet, and it has not achieved use or implementation beyond experimental stacks, so it is not listed among the standard TCP enhancements in this roadmap.

4.2. Fundamental Changes ⚡

like the Standards Track documents listed in Section 3.1, there also exist new Experimental RFCs that specify fundamental changes to TCP. At the time of writing, the only example so far is TCP Fast Open, which deviates from the standard TCP semantics of [RFC793].

RFC 7413 E: "TCP Fast Open" (December 2014)

This document [RFC7413] describes TCP Fast Open that allows data to be carried in the SYN and SYN-ACK packets and consumed by the receiver during the initial connection handshake. It saves up to one RTT compared to the standard TCP, which requires a three-way handshake to complete before data can be exchanged.

4.3. Congestion Control Extensions 💅

okay so TCP congestion control has been an EXTREMELY active research area for years 😭 (see RFC 5783, which we get to in Section 7.6 of this doc). it decides how fast so many apps that run on TCP actually go 🚀. a bunch of Experimental RFCs go after the problems with flow start-up, overshoot, and steady-state behavior in the basic RFC 5681 algorithms (see Section 2 of this doc). this part is the glow-up list of TCP congestion control upgrades. the next subsection is all about loss recovery 🎀

RFC 2861 E: "TCP Congestion Window Validation" (June 2000)

this one [RFC2861] says the congestion window should shrink over time when no packets are flowing. that's more aggressive than RFC 5681 (see Section 2 of this doc), which says a TCP sender SHOULD set its congestion window back to the initial window after an idle period of an RTO or greater. it's giving "use it or lose it" 🍂

RFC 3540 E: "Robust Explicit Congestion Notification (ECN) Signaling with Nonces" (June 2003)

this one [RFC3540] is an optional add-on to ECN that protects against accidental or malicious hiding of marked packets from the TCP sender. no sneaky concealment allowed 🫶

RFC 3649 E: "HighSpeed TCP for Large Congestion Windows" (December 2003)

this one [RFC3649] proposes a tweak to TCP's congestion control for connections with large congestion windows. the goal is letting TCP reach higher throughput in high-bandwidth environments 🦋

RFC 3742 E: "Limited Slow-Start for TCP with Large Congestion Windows" (March 2004)

this one [RFC3742] describes a more conservative slow-start behavior. it's there to prevent massive packet losses when a connection is using a really huge congestion window 🧚

RFC 4782 E: "Quick-Start for TCP and IP" (January 2007) (Errata)

this one [RFC4782] specifies the optional Quick-Start mechanism for TCP. it lets connections use higher sending rates at the start of a transfer or after an idle period, as long as there's significant unused bandwidth along the path AND the sender and all of the routers along the path approve that higher rate. so it's a team decision 👑

RFC 5562 E: "Adding Explicit Congestion Notification (ECN) Capability to TCP's SYN/ACK Packets" (June 2009)

this one [RFC5562] is an experimental change to ECN [RFC3168] (see Section 3.2 of this doc) for using ECN in TCP SYN/ACK packets. the idea is to ECN-mark the TCP SYN/ACK packet at an ECN-capable router instead of dropping it, which avoids the harsh penalty of a retransmission timeout for the connection when a SYN/ACK gets dropped 😩

RFC 5690 I: "Adding Acknowledgement Congestion Control to TCP" (February 2010)

this one [RFC5690] describes a congestion control mechanism for acknowledgment (ACK) traffic in TCP. it's based on the acknowledgment congestion control from the Datagram Congestion Control Protocol's (DCCP's) [RFC4340] Congestion Control Identifier (CCID) 2 [RFC4341] 🌈

RFC 6928 E: "Increasing TCP's Initial Window" (April 2013)

this one [RFC6928] proposes raising the TCP initial window from between 2 and 4 segments (as RFC 3390 specifies, see Section 3.2 of this doc) up to 10 segments. if performance issues show up, it falls back to the existing recommendation 🍓

4.4. Loss Recovery Extensions 🩹

RFC 5827 E: "Early Retransmit for TCP and Stream Control Transmission Protocol (SCTP)" (April 2010)

this one [RFC5827] proposes the "Early Retransmit" mechanism for TCP (and SCTP). it can recover lost segments when a connection's congestion window is small. in certain special situations, Early Retransmit lowers the number of duplicate acknowledgments needed to trigger fast retransmit, so segment losses get recovered without waiting around for a long retransmission timeout ⏰

RFC 6069 E: "Making TCP More Robust to Long Connectivity Disruptions (TCP-LCD)" (December 2010)

this one [RFC6069] explains how standard ICMP messages can tell true congestion loss apart from non-congestion loss caused by connectivity disruptions. it proposes a reversion strategy for TCP's retransmission timer, so it can notice faster whether connectivity has come back 📡

RFC 6937 E: "Proportional Rate Reduction for TCP" (May 2013)

this one [RFC6937] describes an experimental Proportional Rate Reduction (PRR) algorithm. it's an alternative to the widely deployed Fast Recovery algorithm, and it's meant to make the amount of data TCP sends during loss recovery more accurate 🎯

4.5. Detection and Prevention of Spurious Retransmissions 🔍

on top of the Standards Track extensions for dealing with spurious retransmissions in Section 3.4, there are Experimental proposals too 💜

RFC 3522 E: "The Eifel Detection Algorithm for TCP" (April 2003)

the Eifel detection algorithm [RFC3522] lets a TCP sender figure out after the fact whether it went into loss recovery for no reason. it does this by using the TCP timestamp option to solve the ACK ambiguity 🕵️‍♀️

RFC 3708 E: "Using TCP Duplicate Selective Acknowledgement (DSACKs) and Stream Control Transmission Protocol (SCTP) Duplicate Transmission Sequence Numbers (TSNs) to Detect Spurious Retransmissions" (February 2004)

here's the abstract, word for word:

"TCP and Stream Control Transmission Protocol (SCTP) provide notification of duplicate segment receipt through Duplicate Selective Acknowledgement (DSACKs) and Duplicate Transmission Sequence Number (TSN) notification, respectively. This document presents conservative methods of using this information to identify unnecessary retransmissions for various applications."

RFC 4653 E: "Improving the Robustness of TCP to Non-Congestion Events" (August 2006)

with non-congestion events like packet reordering, an out-of-order segment doesn't automatically mean a lost segment plus congestion. this one [RFC4653] proposes raising the threshold for triggering a fast retransmission, from the fixed three duplicate ACKs to about one congestion window of data. that way true segment loss can be told apart from reordering 🔀

4.6. TCP Timeouts ⏱️

besides the well-known retransmission timeout, the TCP standard [RFC793] defines other timeouts too. this section lists the docs that deal with TCP's various timeouts 🫶

RFC 5482 S: "TCP User Timeout Option" (March 2009)

as a local per-connection parameter, the TCP user timeout controls how long transmitted data can stay unacknowledged before a connection gets forcefully closed. this one [RFC5482] specifies the TCP User Timeout Option, which lets one end of a TCP connection advertise its current user timeout value. that gives the other end advice on adjusting its own user timeout 💬

4.7. Multipath TCP 🛣️

MultiPath TCP (MPTCP) is an ongoing effort in the IETF. it lets a TCP connection use multiple IP addresses / interfaces at the same time, spreading its data across several subflows, while still showing a regular TCP interface to applications. the perks include better resource utilization, better throughput, and smoother reaction to failures 🌊 the docs listed here specify the Multipath TCP scheme, and the docs in Sections 7.2, 7.4, and 7.5 give some extra background.

RFC 6356 E: "Coupled Congestion Control for Multipath Transport Protocols" (October 2011)

this one [RFC6356] presents a congestion control algorithm for multipath transport protocols like Multipath TCP. it couples the congestion control algorithms on different subflows by linking their increase functions, and it dynamically controls the overall aggressiveness of the multipath flow. the result is fair to TCP at bottlenecks while moving traffic away from congested links 🤝

RFC 6824 E: "TCP Extensions for Multipath Operation with Multiple Addresses" (January 2013) (Errata)

this one [RFC6824] presents the protocol changes needed to add multipath capability to TCP. specifically, it covers signaling and setting up multiple paths ("subflows"), managing those subflows, reassembling data, and terminating sessions 🧩

5. TCP Parameters at IANA 📋

RFCs listed here describe both the procedures the Internet Assigned Numbers Authority (IANA) uses when handling assignments, and the procedures an RFC author should follow when requesting new TCP option code points 🎀

RFC 2780 B: "IANA Allocation Guidelines For Values In the Internet Protocol and Related Headers" (March 2000)

here's the abstract of RFC 2780 [RFC2780], verbatim:

"This memo provides guidance for the IANA to use in assigning parameters for fields in the IPv4, IPv6, ICMP, UDP and TCP protocol headers."

RFC 4727 S: "Experimental Values in IPv4, IPv6, ICMPv4, ICMPv6, UDP, and TCP Headers" (November 2006)

this one [RFC4727] reserves both TCP options 253 and 254 for experimentation. when those experiments get deployed on the Internet, they should follow the additional requirements in RFC 6994 (see below in Section 5) 🧪

RFC 6335 B: "Internet Assigned Numbers Authority (IANA) Procedures for the Management of the Service Name and Transport Protocol Port Number Registry" (August 2011)

here's the abstract of RFC 6335 [RFC6335], verbatim:

"This document defines the procedures that the Internet Assigned Numbers Authority (IANA) uses when handling assignment and other requests related to the Service Name and Transport Protocol Port Number registry."

RFC 6994 S: "Shared Use of Experimental TCP Options (August 2013)

this one [RFC6994] describes how the experimental TCP option code points can support multiple TCP extensions at once, even within the same connection. it also creates an IANA registry for extensions to the experimental code points 🌈

6. Historic and Undeployed Extensions ✨

okay bestie, this section is basically the "graveyard" of TCP ideas 🪦💀 These RFCs defined extensions that never really got implementers excited, or never got widely deployed, or turned out to be defective for general use. Most of them were reclassified by [RFC6247] to Historic status, so they're officially retired now 🫶

RFC 721 U: "Out-of-Band Control Signals in a Host-to-Host Protocol" (September 1976): lack of interest 🦋

RFC 721 [RFC721] tackles the problem of implementing a reliable out-of-band signal (interrupts) for use in a host-to-host protocol. The proposal was not included in the final TCP specification, so it never made it past the drafting stage 🥲

RFC 1078 U: "TCP Port Service Multiplexer (TCPMUX)" (November 1988): lack of interest 🍓

This document [RFC1078] proposes a protocol to contact multiple services on a single well-known TCP port, using a service name instead of a well-known number. Very clever idea, just not one the community picked up 🧚

RFC 1106 H: "TCP Big Window and Nak Options" (June 1989): found defective 💅

This RFC [RFC1106] defined an alternative to the Window Scale option for using large windows, and it described the "negative acknowledgment" or NAK option. There's a comparison of NAK and SACK methods and some early discussion of TCP over satellite issues. RFC 1110 (see below in Section 6) explains some problems with the approaches described in RFC 1106. The options in this document have not been adopted by the larger community, although NAKs are used in the SCPS-TP adaptation of TCP for satellite and spacecraft use, developed by the Consultative Committee for Space Data Systems (CCSDS). So the idea lives on, just in a different outfit 🛰️✨

RFC 1110 H: "A Problem with the TCP Big Window Option" (August 1989): deprecates RFC 1106 🙈

Abstract of RFC 1110 [RFC1110]: "The TCP Big Window option discussed in RFC 1106 will not work properly in an Internet environment which has both a high bandwidth * delay product and the possibility of disordering and duplicating packets. In such networks, the window size must not be increased without a similar increase in the sequence number space. Therefore, a different approach to big windows should be taken in the Internet."

Basically, RFC 1110 called out that RFC 1106's big window idea breaks down on fast, messy networks 😭

RFC 1146 H: "TCP Alternate Checksum Options" (March 1990): lack of interest 🔥

This document [RFC1146] defined more robust TCP checksums than the 16-bit ones-complement checksum in use today. A typographical error in RFC 1145 is fixed in RFC 1146; otherwise, the documents are the same 📝

RFC 1263 I: "TCP Extensions Considered Harmful" (October 1991): lack of interest 🌸

This document [RFC1263] argues against "backwards compatible" TCP extensions, which is a very spicy take 🌶️ It specifically calls out several TCP enhancements that have been successful, including timestamps, window scaling, PAWS, and SACK. RFC 1263 presents an alternative called "protocol evolution," where several evolutionary versions of TCP would exist on hosts. These distinct TCP versions would represent upgrades to each other and could be header incompatible. Interoperability would be provided by a virtualization layer that selects the right TCP version for a particular connection. This idea did not catch on with the community, while the type of extensions RFC 1263 specifically targeted as harmful did become popular. Oops 💀

RFC 1379 H: "Extending TCP for Transactions -- Concepts" (November 1992): found defective 🧚

See RFC 1644, in Section 6 below.

RFC 1644 H: "T/TCP -- TCP Extensions for Transactions Functional Specification" (July 1994): found defective 💜

The inventors of TCP believed that cached connection state could have been used to eliminate TCP's three-way handshake, to support two-packet request/response exchanges. RFC 1379 [RFC1379] (see above in Section 6) and RFC 1644 [RFC1644] show that this is far from simple. On top of that, T/TCP floundered on the ease of denial-of-service attacks that can result, which is a big nope 🙅‍♀️ One idea pioneered by T/TCP lives on in RFC 2140 (see Section 4.1 of this document), in the sharing of state across connections. Iconic survival story ✨

RFC 1693 H: "An Extension to TCP: Partial Order Service" (November 1994): lack of interest 🎀

This document [RFC1693] defines a TCP extension for applications that do not care about the order in which application-layer objects are received. Examples are multimedia and database applications. In practice, these applications either accept the possible performance loss because of TCP's strict ordering or use specialized transport protocols other than TCP, such as PR-SCTP [RFC3758] 🦋

RFC 1705 I: "Six Virtual Inches to the Left: The Problem with IPng" (October 1994): lack of interest 🌈

To overcome the exhaustion of the IP class B address space, this document [RFC1705] suggests that a new version of TCP (TCPng) needs to be developed and deployed. It proposes that a globally unique address be assigned to the transport layer, to uniquely identify an Internet host without specifying any routing information. Later work on splitting locator and identifier values is summarized well in [RFC6115], but no resulting changes to TCP have occurred 🫶

RFC 6013 E: "TCP Cookie Transactions (TCPCT)" (January 2011): lack of interest 🍓

This document [RFC6013] describes a method to exchange a cookie (nonce) during connection establishment, to negotiate elimination of receiver state. These cookies are later used to inhibit premature closing of connections and reduce retention of state after the connection has terminated.

Since the cookie pair is too large to fit with the other TCP options in the 40 bytes of TCP option space, the document further describes a method to extent the option space after the connection establishment.

Although RFC 6013 was published in 2011, the authors of this document places it in this section of the roadmap document due to two factors:

(a) The authors are not aware of any wide deployment and use of RFC 6013.
(b) RFC 6013 uses experimental TCP option code points, which prohibits a large-scale deployment.

7. Support Documents 🧸

okay so this section is the "extra reading" pile, and honestly it's a whole vibe 📚 It doesn't necessarily define current protocol behaviors, but it's super useful for TCP implementers who want the backstory. Section 7.1 covers foundational RFCs that give modern readers a better understanding of the principles behind TCP's behaviors and how it developed over the years. Section 7.2 has architectural guidelines and principles for TCP architects and designers. The documents in Section 7.3 give advice on using TCP in network situations that are harder than typical wired links. Guidance for developing, analyzing, and evaluating TCP lives in Section 7.4. Some implementation notes and implementation advice can be found in Section 7.5. RFCs that describe tools for testing and debugging TCP implementations, or that contain high-level tutorials on the protocol, are listed in Section 7.6. The TCP Management Information Bases are described in Section 7.7, and Section 7.8 lists a number of case studies that have explored TCP performance 🔍✨

7.1. Foundational Works 🌷

The documents listed in this section contain information that is largely duplicated by the standards documents we already covered. However, some of them have a greater depth of problem statement explanation or other context. In particular, RFCs 813 - 817 (known as the "Dave Clark Five") describe some early problems and solutions. RFC 815 only describes the reassembly of IP fragments and is not included in this TCP roadmap 👑

RFC 675 U: "Specification of Internet Transmission Control Program" (December 1974) 🐣

This document [RFC675] is a very early precursor of the fundamental RFC 793 (see Section 2 of this document), which already contained the three-way handshake in its final form and the concept of sliding windows for reliable data transmission. Apart from that, the segment layout is totally different and the specified API differs from the latter RFC 793 (see Section 2 of this document) 🧠

RFC 761 U: "DoD Standard Transmission Control Protocol" (January 1980) 🎀

This document [RFC761] is the immediate precursor of RFC 793 (see Section 2 of this document). The header format, the connection establishment (including the different connection states), and the overall API correspond mostly to the final Standard RFC 793 (see Section 2 of this document) 💖

RFC 813 U: "Window and Acknowledgement Strategy in TCP" (July 1982) 🦋

This document [RFC813] contains an early discussion of Silly Window Syndrome and its avoidance, and it motivates and describes the use of delayed acknowledgments 🙌

RFC 814 U: "Name, Addresses, Ports, and Routes" (July 1982) 🗺️

Suggestions and guidance for designing tables and algorithms to keep track of various identifiers within a TCP/IP implementation are provided by this document [RFC814] 🧚

RFC 816 U: "Fault Isolation and Recovery" (July 1982) 🛠️

In this document [RFC816], TCP's response to indications of network error conditions, such as timeouts or received ICMP messages, is discussed 🫣

RFC 817 U: "Modularity and Efficiency in Protocol Implementation" (July 1982) 🧩

This document [RFC817] contains implementation suggestions that are general and not TCP specific. However, they have been used to develop TCP implementations, and they describe some performance implications of the interactions between various layers in the Internet stack ⭐

RFC 872 U: "TCP-on-a-LAN" (September 1982) 🌈

Conclusion of RFC 872 [RFC872]: "The sometimes-expressed fear that using TCP on a local net is a bad idea is unfounded."

Honestly, the people worried about this were wrong, and RFC 872 says so 💅

RFC 896 U: "Congestion Control in IP/TCP Internetworks" (January 1984) 🌊

This document [RFC896] contains some early experiences with congestion collapse and some initial thoughts on how to avoid it using congestion control in TCP. Furthermore, it defined an algorithm for efficient transmission of small packets that is today known as the Nagle algorithm 🍼✨

RFC 964 U: "Some Problems with the Specification of the Military Standard Transmission Control Protocol" (November 1985) 🪄

This document [RFC964] points out several specification bugs in the US Military's MIL-STD-1778 document, which was intended as a successor to RFC 793 (see Section 2 of this document). This serves to remind us of the difficulty in specification writing, even when we work from existing documents! 😭

7.2. Architectural Guidelines 🏛️✨

okay so this bit is basically the "big picture" crew. Some of these docs are pure architecture vibes, and others define TCP and congestion-control stuff that's broadly useful and changes how TCP's congestion control works. A few of them are straight from the Internet Architecture Board (IAB) 🎀, who wanted to share their guidance on congestion control across the Internet.

RFC 1958 I: "Architectural Principles of the Internet" (June 1996)

This one is the foundation 🧱 [RFC1958]. It lays out the core principles behind how the Internet is built, plus design guidelines that have held up as the Internet kept growing. It's giving "read this before you build anything" energy.

RFC 2914 B: "Congestion Control Principles" (September 2000)

This doc explains why end-to-end congestion control matters 🌊 [RFC2914]. Without it you get congestion collapse, and you also don't get fairness for TCP. Later TCP work added some more aggressive mechanisms than Reno TCP has, and RFC 5033 (see Section 7.4 of this document) gives extra guidance on using those algorithms 💅. The big architectural point from RFC 2914 still holds up: standards work has a real role in defining the protocol bits that affect performance, so we can dodge congestion collapse scenarios. Iconic 👑.

RFC 3360 B: "Inappropriate TCP Resets Considered Harmful" (August 2002)

This is basically a public plea 🙏 [RFC3360] asking firewall vendors to stop sending unnecessary TCP RST (Reset) packets when unassigned TCP header bits are in use. Why? Because that kind of behaviour blocks the protocol from getting new extensions and evolving, which could really hurt the Internet down the line 😭.

RFC 3439 I: "Some Internet Architectural Guidelines and Philosophy" (December 2002)

This one updates RFC 1958 (see above in Section 7.2) 🔄 [RFC3439] with some philosophical guidelines for people designing and building Internet backbone networks. Its main idea is the Simplicity Principle, which says complexity is the biggest blocker to scaling efficiently 🧠✨. Simple is so back.

RFC 4774 B: "Specifying Alternate Semantics for the Explicit Congestion Notification (ECN) Field" (November 2006)

This doc digs into the messy questions around defining alternate meanings for the ECN field 🚦 [RFC4774]. It also sets out requirements so those new meanings can safely coexist with routers that don't know about them yet. Very careful, very responsible, very slay 🫶.

RFC 6182 I: "Architectural Guidelines for Multipath TCP Development" (March 2011)

Here's the gist 🦋 [RFC6182]: it lays out architectural guidelines for building a multipath transport protocol, and shows how those pieces come together in Multipath TCP (MPTCP) (see Section 4.7 of this document) 🌈. It also lists some high-level design decisions that give the MPTCP protocol its foundations, based on those architectural requirements. Main character energy, honestly.

7.3. Difficult Network Environments 🌧️🛰️

okay, so as the internetworking world started exploring wireless, satellite, cellular, and other link-layer tech, people built up a huge pile of work on making TCP perform better over those links 💜. The RFCs in this section cover some of the trickier network environments and how TCP behaves in them. Hard mode, but make it cute 🎀.

RFC 2488 B: "Enhancing TCP Over Satellite Channels using Standard Mechanisms" (January 1999)

This one [RFC2488] says that TCP works fine over satellite, and there are already IETF-standardised mechanisms that help TCP use the available capacity of the path way better 🛰️. It goes through some of those TCP mitigations. The best part is that every mitigation in this doc is either an IETF standards track mechanism or complies with IETF standards, so you're not stepping outside the approved toolbox 🧰✅.

RFC 2757 I: "Long Thin Networks" (January 2000)

Long thin networks are the ones with low bandwidth and high delay, like geosynchronous satellite links 🌍. This doc [RFC2757] looks at ways to improve TCP performance there, and it defines a particular set of TCP options that should work well in those environments and still be safe for the global Internet 🫧. RFCs 3150 and 3155 (see below in Section 7.3) talk about the same environments in more depth, and where they overlap with RFC 2757, you should prefer those two docs (see Section 7.3 of this document) 📚. Read the deeper ones first, bestie.

This doc [RFC2760] is a tour of experimental ways to make TCP faster over long-delay or error-prone paths 🧪. It covers T/TCP, larger initial windows, byte counting, delayed acknowledgments, slow start thresholds, NewReno and SACK-based loss recovery, FACK [MM96], 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. That's a LOT, I know 😭. And while RFC 2488 (see above in Section 7.3) looked at standard extensions, this one is focused on the more experimental stuff 🔬.

This is a survey 🗺️ [RFC3135] of Performance Enhancing Proxies (PEPs). These get used a lot to fix TCP performance problems caused by specific link environments, like satellite, wireless WAN, and wireless LAN. The doc describes the different types of PEPs and the mechanisms they use to make things faster 🚀.

RFC 3150 B: "End-to-end Performance Implications of Slow Links" (July 2001)

This one [RFC3150] gives performance recommendations for paths that go through really low bit-rate links 🐢. It's useful anywhere hosts can max out the available bandwidth, but the design space explicitly includes connections over 56 Kb/second modem links or 4.8 Kb/second wireless access links, and both of those are still widely deployed 📟. Dial-up nostalgia, but make it technical 💀.

RFC 3155 B: "End-to-end Performance Implications of Links with Errors" (August 2001)

This doc [RFC3155] looks at the TCP mechanisms that cause trouble in environments with high uncorrected error rates 📉. It also talks about how to fix those problems without putting intermediate devices in the connection 🙌.

RFC 3366 B: "Advice to link designers on link Automatic Repeat reQuest (ARQ)" (August 2002)

This doc [RFC3366] is advice for the people designing digital communication gear and link-layer protocols that use ARQ techniques 🔧. It assumes those designers want to support Internet protocols but might not know much about Internet architecture, or how their design choices affect the performance and efficiency of Internet traffic on their links 🫶.

RFC 3449 B: "TCP Performance Implications of Network Path Asymmetry" (December 2002)

This one [RFC3449] describes TCP performance problems caused by asymmetric paths ⚖️. These show up in several access networks, including bandwidth-asymmetric networks and packet radio subnetworks, for different underlying reasons. But the end result is the same either way: performance often tanks because the ACK feedback from the receiver to the sender is imperfect and variable 📉💔. The doc also details several mitigations for these effects, which have either been proposed or evaluated in the literature, or are actually deployed in networks right now 🛠️✨.

RFC 3481 B: "TCP over Second (2.5G) and Third (3G) Generation Wireless Networks" (February 2003)

This doc [RFC3481] describes a profile for tuning TCP so it can handle paths that include 2.5G and 3G wireless networks 📱. Old phone network, new TCP tricks 🧚.

RFC 3819 B: "Advice for Internet Subnetwork Designers" (July 2004)

This one [RFC3819] explains how some lower-layer behaviours can hurt TCP performance 😤, and gives guidance on designing lower-layer networks and protocols that play nicely with TCP 🫶. RFC 3366 (see above in Section 7.3) focuses specifically on ARQ mechanisms, while RFC 3819 covers more of the other aspects of the underlying layers 💖.

7.4. Guidance for Developing, Analyzing, and Evaluating TCP 🔬

okay so this part is basically the "how do we build, test, and judge new TCP stuff properly" corner 💅 these docs give general guidance for developing, analyzing, and evaluating TCP. some of them get into what makes a congestion control protocol "safe" for Internet deployment, plus how to measure the properties of congestion control mechanisms and transport protocols. it's giving science fair energy, and I'm obsessed 🧪

RFC 5033 B: "Specifying New Congestion Control Algorithms" (August 2007)

This doc [RFC5033] looks at how to evaluate suggested congestion control algorithms that differ from the principles in RFC 2914 (see Section 7.2 of this document). it's super useful for people writing those algorithms, and for IETF members reviewing the docs too 🫶

RFC 5166 I: "Metrics for the Evaluation of Congestion Control Mechanisms" (March 2008)

This doc [RFC5166] talks about the metrics you need to consider when evaluating new or modified congestion control mechanisms for the Internet. among other things, it covers throughput, delay, loss rates, response times, fairness, and robustness for challenging environments 📊✨

RFC 6077 I: "Open Research Issues in Internet Congestion Control" (February 2011)

This doc [RFC6077] sums up the main open problems in Internet congestion control. if you're a newcomer, it's the perfect starting point 🌸 it describes several new challenges that keep getting more important as the network grows, plus some issues that have been around for many years. literally a treasure map 🗺️

RFC 6181 I: "Threat Analysis for TCP Extensions for Multipath Operation with Multiple Addresses" (March 2011)

This doc [RFC6181] is a threat analysis for Multipath TCP (MPTCP) (see Section 4.7 of this document). it goes through several types of attacks and gives MPTCP designers recommendations for writing an MPTCP specification that's as secure as current single-path TCP. main character security energy 🔐💜

RFC 6349 I: "Framework for TCP Throughput Testing" (August 2011)

From the Abstract of RFC 6349 [RFC6349]: "This framework describes a practical methodology for measuring end-to-end TCP Throughput in a managed IP network. The goal is to provide a better indication in regard to user experience. In this framework, TCP and IP parameters are specified to optimize TCP Throughput."

7.5. Implementation Advice 🛠️

this section is the "okay but how do I actually build it" crew. some of these are old classics, some are fixes for real-world bugs, and yes, a couple of them are about checksums, which are lowkey iconic 🤓

RFC 794 U: "PRE-EMPTION" (September 1981)

This doc [RFC794] clarifies that operating systems have to manage their limited resources, which can include TCP connection state. those decisions can be made with application input, but they don't have to be part of the TCP protocol specification itself 🧠

RFC 879 U: "The TCP Maximum Segment Size and Related Topics" (November 1983)

Abstract of RFC 879 [RFC879]: "This memo discusses the TCP Maximum Segment Size Option and related topics. The purposes [sic] 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'."

RFC 1071 U: "Computing the Internet Checksum" (September 1988) (Errata)

This doc [RFC1071] lists a bunch of implementation techniques for computing the Internet checksum efficiently. the checksum is used by TCP, so this one's a must-read 💖

RFC 1624 I: "Computation of the Internet Checksum via Incremental Update" (May 1994)

Incrementally updating the Internet checksum is useful to routers when they update IP checksums. some middleboxes that alter TCP headers may also be able to update the TCP checksum incrementally. this doc [RFC1624] expands on the explanation of the incremental update procedure in RFC 1071 (see above in Section 7.5) 🧮✨

RFC 1936 I: "Implementing the Internet Checksum in Hardware" (April 1996)

This doc [RFC1936] explains why you'd implement the Internet checksum in hardware instead of software, and it gives an implementation example 🔧

RFC 2525 I: "Known TCP Implementation Problems" (March 1999)

From the Abstract of RFC 2525 [RFC2525]: "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."

RFC 2923 I: "TCP Problems with Path MTU Discovery" (September 2000)

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 acknowledgments (ACKs) due to confusion between Maximum Segment Size (MSS) and segment size, and MSS advertisement based on PMTU." [RFC2923]

the black hole problem is giving horror movie 👻 but it's good to know about it 💀

RFC 3493 I: "Basic Socket Interface Extensions for IPv6" (February 2003)

This doc [RFC3493] describes the de facto standard sockets API for programming with TCP. it's implemented pretty much everywhere in modern operating systems and programming languages, so it's basically everywhere 🌈

RFC 6056 B: "Recommendations for Transport-Protocol Port Randomization" (December 2010)

This doc [RFC6056] describes a number of simple and efficient methods for selecting the client port number. it makes it harder for an attacker to guess the correct five-tuple (Protocol, Source/Destination Address, Source/Destination Port) 🙈🔒

RFC 6191 B: "Reducing the TIME-WAIT State Using TCP Timestamps" (April 2011)

This doc [RFC6191] covers using the TCP Timestamps option (RFC 7323, see Section 3.1 of this document) with heuristics to decide whether to allow the creation of a new incarnation of a connection that's in the TIME-WAIT state. it's a clever trick and I'm so here for it 🦋

RFC 6429 I: "TCP Sender Clarification for Persist Condition" (December 2011)

This doc [RFC6429] clarifies what a TCP can do on connections that are experiencing the Zero Window Probe (ZWP) condition 💅

RFC 6897 I: "Multipath TCP (MPTCP) Application Interface Considerations" (March 2013)

This doc [RFC6897] looks at the impact Multipath TCP (MPTCP) (see Section 4.7 of this document) may have on applications. it also covers compatibility issues when MPTCP is combined with applications that aren't MPTCP-aware. finally, it describes a basic API that's a simple extension of TCP's interface for MPTCP-aware applications 🎀

7.6. Tools and Tutorials 🧰

this is the "I'm new, help" section, and honestly the best place to start if you want to poke around and learn 🧚

RFC 1180 I: "TCP/IP Tutorial" (January 1991) (Errata)

This doc [RFC1180] is an extremely brief overview of the TCP/IP protocol suite as a whole. it explains a bit about how and where TCP fits in 🌸

RFC 1470 I: "FYI on a Network Management Tool Catalog: Tools for Monitoring and Debugging TCP/IP Internets and Interconnected Devices" (June 1993)

A few of the tools this doc [RFC1470] describes are still maintained and in use today, for example, ttcp and tcpdump. however, lots of the tools don't relate specifically to TCP, and they're no longer used or easily available 🥲

RFC 2398 I: "Some Testing Tools for TCP Implementors" (August 1998)

This doc [RFC2398] describes a number of TCP packet generation and analysis tools. some of them aren't readily available or widely used anymore, but for the most part they're still relevant and usable 🍓

RFC 5783 I: "Congestion Control in the RFC Series" (February 2010)

This doc [RFC5783] gives an overview of the RFCs related to congestion control that had been published at the time. the focus is on end-host-based congestion control 💜

7.7. MIB Modules 📚

okay, MIB history time, and it's a glow-up story 🌟 the first MIB module for the Simple Network Management Protocol (SNMP) was one big monolithic MIB module called MIB-I, defined in RFC 1156. that evolved into the MIB-II specification in RFC 1213, which obsoletes RFC 1156. then people realized one giant monolithic MIB module just wasn't scalable, given how many MIB data definitions needed to be included and how broad they were. so more MIB modules got defined, and the parts of MIB-II that needed to evolve got split off. eventually the rest of MIB-II was split off too, with the TCP-specific part documented in RFC 2012. RFC 2012 was then obsoleted by RFC 4022, which is the primary TCP MIB document at the time of writing. if you're a current TCP implementer, RFC 4022 should be supported 🫶

RFC 1156 S: "Management Information Base for Network Management of TCP/IP-based Internets" (May 1990)

This doc [RFC1156] 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 RFC for MIB-I 🎀

RFC 1213 S: "Management Information Base for Network Management of TCP/IP-based internets: MIB-II" (March 1991)

This doc [RFC1213] describes the second version of the MIB, in a monolithic form. it's the immediate successor of RFC 1158, with minor modifications. it obsoletes the MIB-I, defined in RFC 1156 (see above in Section 7.7) 🌷

RFC 2012 S: "SNMPv2 Management Information Base for the Transmission Control Protocol using SMIv2" (November 1996)

In an update to RFC 1213 (see Section 7.7 of this document), this doc [RFC2012] defines the TCP MIB by splitting out the TCP-specific portions. it's now obsoleted by RFC 4022 (see below in Section 7.7) 🦋

RFC 2452 S: "IP Version 6 Management Information Base for the Transmission Control Protocol" (December 1998)

This doc [RFC2452] augments RFC 2012 (see Section 7.7 of this document) by adding an IPv6-specific connection table. the rest of RFC 2012 holds for any IP version. RFC 2452 is now obsoleted by RFC 4022 (see below in Section 7.7) 🧚

Although it is a Standards Track RFC, RFC 2452 is considered a historic mistake by the MIB community, as it is based on the idea of parallel IPv4 and IPv6 structures. Although IPv6 requires new structures, the community has decided to define a single generic structure for both IPv4 and IPv6. This will aid in definition, implementation, and transition between IPv4 and IPv6. 💀

RFC 4022 S: "Management Information Base for the Transmission Control Protocol (TCP)" (March 2005)

This doc [RFC4022] obsoletes RFCs 2012 and 2452 (see above in Section 7.7) and specifies the current standard for the TCP MIB that should be deployed. the current queen 👑

RFC 4898 S: "TCP Extended Statistics MIB" (May 2007)

This doc [RFC4898] describes extended performance statistics for TCP. they're designed to use TCP's ideal vantage point to diagnose performance problems in both the network and the application. it's giving detective energy 🕵️‍♀️✨

7.8. Case Studies ✨

Okay bestie, this is the fun part where we look at real-life experiments. 🧪 Each one is a little case study from the TCP family tree. 🌳

RFC 700 U: "A Protocol Experiment" (August 1974) 🕰️

Okay so [RFC700] is a field report about putting a super early version of TCP to work. It's the so-called INWN #39 protocol, which Cerf and Kahn first described in INWG Note #39 [CK73]. The goal was to use a PDP-11 line printer over the ARPANET. Vintage queen behavior 👑

RFC 889 U: "Internet Delay Experiments" (December 1983) ⏱️

This one is [RFC889], a status report on experiments with how TCP works out its retransmission timeout. It also gives advice for implementers, so take notes 📝

RFC 1337 I: "TIME-WAIT Assassination Hazards in TCP" (May 1992) 💀

[RFC1337] calls out a problem with acting on reset segments that show up while you're in the TIME-WAIT state. 🙈 The main recommendation is that hosts in TIME-WAIT ignore resets. Lowkey this one might not be widely implemented yet, so keep an eye on it 👀

RFC 2415 I: "Simulation Studies of Increased Initial TCP Window Size" (September 1998) 📈

[RFC2415] shares results from simulations using initial windows bigger than 1 segment. The analysis shows that user-perceived performance can get better when the initial window goes up to 3 segments. Main character glow-up ✨

RFC 2416 I: "When TCP Starts Up With Four Packets Into Only Three Buffers" (September 1998) 📦

This one is [RFC2416]. It uses simulation results to clear up some worries about starting with an initial window of 4 segments when the network path has less provisioning. Bestie, that's a very specific worry and I respect it 🫶

RFC 2884 I: "Performance Evaluation of Explicit Congestion Notification (ECN) in IP Networks" (July 2000) 🦋

[RFC2884] describes experimental results showing that ECN improves performance for both short-lived and long-lived connections. Slay 💅

8. Undocumented TCP Features 🔮

Here's the tea. ☕ There are a few important implementation tactics for TCP that haven't been written down in any RFC yet. This roadmap is mostly about mapping the TCP RFCs, but this section is here anyway, because implementers really need to know about these important issues 🫶

Header Prediction 🪄

Header prediction is a trick for speeding up how segments get processed. Van Jacobson and Mike Karels came up with it in the late 1980s. The big idea is that you can save processing time when most of a segment's fields can be predicted from the segments before it. Jacobson posted a great explanation to the TCP-IP mailing list on March 9, 1988 (see [Jacobson] for the full message). Here's the quote, verbatim, because it's too good to paraphrase:

Quite a bit of the speedup comes from an algorithm that we ('we' refers to collaborator Mike Karels and myself) are calling "header prediction". The idea is that if you're in the middle of a bulk data transfer and have just seen a packet, you know what the next packet is going to look like: It will look just like the current packet with either the sequence number or ack number updated (depending on whether you're the sender or receiver). Combining this with the "Use hints" epigram from Butler Lampson's classic "Epigrams for System Designers", you start to think of the tcp state (rcv.nxt, snd.una, etc.) as "hints" about what the next packet should look like. If you arrange those "hints" so they match the layout of a tcp packet header, it takes a single 14-byte compare to see if your prediction is correct (3 longword compares to pick up the send & ack sequence numbers, header length, flags and window, plus a short compare on the length). If the prediction is correct, there's a single test on the length to see if you're the sender or receiver followed by the appropriate processing. E.g., if the length is non-zero (you're the receiver), checksum and append the data to the socket buffer then wake any process that's sleeping on the buffer. Update rcv.nxt by the length of this packet (this updates your "prediction" of the next packet). Check if you can handle another packet the same size as the current one. If not, set one of the unused flag bits in your header prediction to guarantee that the prediction will fail on the next packet and force you to go through full protocol processing. Otherwise, you're done with this packet. So, the total tcp protocol processing, exclusive of checksumming, is on the order of 6 compares and an add.

Forward Acknowledgement (FACK) 🎯

FACK [MM96] has an alternate algorithm for triggering fast retransmit [RFC5681], and it's based on how big the SACK scoreboard is. The goal is to trigger fast retransmit as soon as the receiver's reassembly queue is bigger than the duplicate ACK threshold. You can tell that from the difference between the forward-most SACK block edge and SND.UNA. This algorithm quickly and reliably triggers fast retransmit when there are burst losses, often on the first SACK after a loss. A threshold-based algorithm like this also triggers fast retransmit right away when there's any reordering with extent greater than the duplicate ACK threshold. FACK is implemented in Linux and turned on by default 🐧

Congestion Control for High Rate Flows 🚀

Over the last decade, researchers have put a lot of effort into experimental TCP congestion control changes that aim for high throughput with shorter startup and recovery times. Only a few of these have RFCs, including HighSpeed TCP [RFC3649], Limited Slow-Start [RFC3742], and Quick-Start [RFC4782]. (See Section 4.3 of this document for more on each one.) High-rate congestion control is still considered an open issue in congestion control research, though 🧠

Some other schemes have been published as Internet-Drafts. Examples are CUBIC [CUBIC] (the standard TCP congestion control algorithm in Linux), Compound TCP [CTCP], and H-TCP [HTCP]. Others have been discussed a bit by the IETF. Most of this work hasn't been adopted within the IETF yet, though, so the majority of it sits outside the RFC series. It may be discussed in other products of the IRTF Internet Congestion Control Research Group (ICCRG) 🌈

9. Security Considerations 🔐

This document introduces no new security considerations. Each RFC listed in this document attempts to address the security considerations of the specification it contains. Security is a whole vibe, so each spec is supposed to handle its own 🛡️

10. References 📚

10.1. Normative References 📖

[RFC675]   Cerf, V., Dalal, Y., and C. Sunshine, "Specification of
           Internet Transmission Control Program", RFC 675, December
           1974, <http://www.rfc-editor.org/info/rfc675>.

[RFC700]   Mader, E., Plummer, W., and R. Tomlinson, "Protocol
           experiment", RFC 700, August 1974,
           <http://www.rfc-editor.org/info/rfc700>.

[RFC721]   Garlick, L., "Out-of-Band Control Signals in a Host-to-
           Host Protocol", RFC 721, September 1976,
           <http://www.rfc-editor.org/info/rfc721>.

[RFC761]   Postel, J., "DoD standard Transmission Control Protocol",
           RFC 761, January 1980,
           <http://www.rfc-editor.org/info/rfc761>.

[RFC793]   Postel, J., "Transmission Control Protocol", STD 7, RFC
           793, September 1981,
           <http://www.rfc-editor.org/info/rfc793>.

[RFC794]   Cerf, V., "Pre-emption", RFC 794, September 1981,
           <http://www.rfc-editor.org/info/rfc794>.

[RFC813]   Clark, D., "Window and Acknowledgement Strategy in TCP",
           RFC 813, July 1982,
           <http://www.rfc-editor.org/info/rfc813>.

[RFC814]   Clark, D., "Name, addresses, ports, and routes", RFC 814,
           July 1982, <http://www.rfc-editor.org/info/rfc814>.

[RFC816]   Clark, D., "Fault isolation and recovery", RFC 816, July
           1982, <http://www.rfc-editor.org/info/rfc816>.

[RFC817]   Clark, D., "Modularity and efficiency in protocol
           implementation", RFC 817, July 1982,
           <http://www.rfc-editor.org/info/rfc817>.

[RFC872]   Padlipsky, M., "TCP-on-a-LAN", RFC 872, September 1982,
           <http://www.rfc-editor.org/info/rfc872>.

[RFC879]   Postel, J., "TCP maximum segment size and related topics",
           RFC 879, November 1983,
           <http://www.rfc-editor.org/info/rfc879>.

[RFC889]   Mills, D., "Internet delay experiments", RFC 889, December
           1983, <http://www.rfc-editor.org/info/rfc889>.

[RFC896]   Nagle, J., "Congestion control in IP/TCP internetworks",
           RFC 896, January 1984,
           <http://www.rfc-editor.org/info/rfc896>.

[RFC964]   Sidhu, D. and T. Blumer, "Some problems with the
           specification of the Military Standard Transmission
           Control Protocol", RFC 964, November 1985,
           <http://www.rfc-editor.org/info/rfc964>.

[RFC1071]  Braden, R., Borman, D., Partridge, C., and W. Plummer,
           "Computing the Internet checksum", RFC 1071, September
           1988, <http://www.rfc-editor.org/info/rfc1071>.

[RFC1078]  Lottor, M., "TCP port service Multiplexer (TCPMUX)", RFC
           1078, November 1988,
           <http://www.rfc-editor.org/info/rfc1078>.

[RFC1106]  Fox, R., "TCP big window and NAK options", RFC 1106, June
           1989, <http://www.rfc-editor.org/info/rfc1106>.

[RFC1110]  McKenzie, A., "Problem with the TCP big window option",
           RFC 1110, August 1989,
           <http://www.rfc-editor.org/info/rfc1110>.

[RFC1122]  Braden, R., "Requirements for Internet Hosts -
           Communication Layers", STD 3, RFC 1122, October 1989,
           <http://www.rfc-editor.org/info/rfc1122>.

[RFC1144]  Jacobson, V., "Compressing TCP/IP headers for low-speed
           serial links", RFC 1144, February 1990,
           <http://www.rfc-editor.org/info/rfc1144>.

[RFC1146]  Zweig, J. and C. Partridge, "TCP alternate checksum
           options", RFC 1146, March 1990,
           <http://www.rfc-editor.org/info/rfc1146>.

[RFC1156]  McCloghrie, K. and M. Rose, "Management Information Base
           for network management of TCP/IP-based internets", RFC
           1156, May 1990, <http://www.rfc-editor.org/info/rfc1156>.

[RFC1180]  Socolofsky, T. and C. Kale, "TCP/IP tutorial", RFC 1180,
           January 1991, <http://www.rfc-editor.org/info/rfc1180>.

[RFC1191]  Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
           November 1990, <http://www.rfc-editor.org/info/rfc1191>.

[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,
           <http://www.rfc-editor.org/info/rfc1213>.

[RFC1263]  O'Malley, S. and L. Peterson, "TCP Extensions Considered
           Harmful", RFC 1263, October 1991,
           <http://www.rfc-editor.org/info/rfc1263>.

[RFC1337]  Braden, B., "TIME-WAIT Assassination Hazards in TCP", RFC
           1337, May 1992, <http://www.rfc-editor.org/info/rfc1337>.

[RFC1379]  Braden, B., "Extending TCP for Transactions -- Concepts",
           RFC 1379, November 1992,
           <http://www.rfc-editor.org/info/rfc1379>.

10.2. Informative References 📚✨

okay bestie, these are the extra reads that back everything up 🫶 they're not required reading but they're the receipts, so here's the full list, nothing skipped 💅

[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, <http://www.rfc-editor.org/info/rfc1470>.
[RFC1624] Rijsinghani, A., "Computation of the Internet Checksum via Incremental Update", RFC 1624, May 1994, <http://www.rfc-editor.org/info/rfc1624>.
[RFC1644] Braden, B., "T/TCP -- TCP Extensions for Transactions Functional Specification", RFC 1644, July 1994, <http://www.rfc-editor.org/info/rfc1644>.
[RFC1693] Connolly, T., Amer, P., and P. Conrad, "An Extension to TCP : Partial Order Service", RFC 1693, November 1994, <http://www.rfc-editor.org/info/rfc1693>.
[RFC1705] Carlson, R. and D. Ficarella, "Six Virtual Inches to the Left: The Problem with IPng", RFC 1705, October 1994, <http://www.rfc-editor.org/info/rfc1705>.
[RFC1936] Touch, J. and B. Parham, "Implementing the Internet Checksum in Hardware", RFC 1936, April 1996, <http://www.rfc-editor.org/info/rfc1936>.
[RFC1958] Carpenter, B., "Architectural Principles of the Internet", RFC 1958, June 1996, <http://www.rfc-editor.org/info/rfc1958>.
[RFC1981] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery for IP version 6", RFC 1981, August 1996, <http://www.rfc-editor.org/info/rfc1981>.
[RFC2012] McCloghrie, K., "SNMPv2 Management Information Base for the Transmission Control Protocol using SMIv2", RFC 2012, November 1996, <http://www.rfc-editor.org/info/rfc2012>.
[RFC2018] Mathis, M., Mahdavi, J., Floyd, S., and A. Romanow, "TCP Selective Acknowledgment Options", RFC 2018, October 1996, <http://www.rfc-editor.org/info/rfc2018>.
[RFC2140] Touch, J., "TCP Control Block Interdependence", RFC 2140, April 1997, <http://www.rfc-editor.org/info/rfc2140>.
[RFC2398] Parker, S. and C. Schmechel, "Some Testing Tools for TCP Implementors", RFC 2398, August 1998, <http://www.rfc-editor.org/info/rfc2398>.
[RFC2415] Poduri, K., "Simulation Studies of Increased Initial TCP Window Size", RFC 2415, September 1998, <http://www.rfc-editor.org/info/rfc2415>.
[RFC2416] Shepard, T. and C. Partridge, "When TCP Starts Up With Four Packets Into Only Three Buffers", RFC 2416, September 1998, <http://www.rfc-editor.org/info/rfc2416>.
[RFC2452] Daniele, M., "IP Version 6 Management Information Base for the Transmission Control Protocol", RFC 2452, December 1998, <http://www.rfc-editor.org/info/rfc2452>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998, <http://www.rfc-editor.org/info/rfc2460>.
[RFC2488] Allman, M., Glover, D., and L. Sanchez, "Enhancing TCP Over Satellite Channels using Standard Mechanisms", BCP 28, RFC 2488, January 1999, <http://www.rfc-editor.org/info/rfc2488>.
[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, <http://www.rfc-editor.org/info/rfc2525>.
[RFC2675] Borman, D., Deering, S., and R. Hinden, "IPv6 Jumbograms", RFC 2675, August 1999, <http://www.rfc-editor.org/info/rfc2675>.
[RFC2757] Montenegro, G., Dawkins, S., Kojo, M., Magret, V., and N. Vaidya, "Long Thin Networks", RFC 2757, January 2000, <http://www.rfc-editor.org/info/rfc2757>.
[RFC2760] Allman, M., Dawkins, S., Glover, D., Griner, J., Tran, D., 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, <http://www.rfc-editor.org/info/rfc2760>.
[RFC2780] Bradner, S. and V. Paxson, "IANA Allocation Guidelines For Values In the Internet Protocol and Related Headers", BCP 37, RFC 2780, March 2000, <http://www.rfc-editor.org/info/rfc2780>.
[RFC2861] Handley, M., Padhye, J., and S. Floyd, "TCP Congestion Window Validation", RFC 2861, June 2000, <http://www.rfc-editor.org/info/rfc2861>.
[RFC2873] Xiao, X., Hannan, A., Paxson, V., and E. Crabbe, "TCP Processing of the IPv4 Precedence Field", RFC 2873, June 2000, <http://www.rfc-editor.org/info/rfc2873>.
[RFC2883] Floyd, S., Mahdavi, J., Mathis, M., and M. Podolsky, "An Extension to the Selective Acknowledgement (SACK) Option for TCP", RFC 2883, July 2000, <http://www.rfc-editor.org/info/rfc2883>.
[RFC2884] Hadi Salim, J. and U. Ahmed, "Performance Evaluation of Explicit Congestion Notification (ECN) in IP Networks", RFC 2884, July 2000, <http://www.rfc-editor.org/info/rfc2884>.
[RFC2914] Floyd, S., "Congestion Control Principles", BCP 41, RFC 2914, September 2000, <http://www.rfc-editor.org/info/rfc2914>.
[RFC2923] Lahey, K., "TCP Problems with Path MTU Discovery", RFC 2923, September 2000, <http://www.rfc-editor.org/info/rfc2923>.
[RFC3042] Allman, M., Balakrishnan, H., and S. Floyd, "Enhancing TCP's Loss Recovery Using Limited Transmit", RFC 3042, January 2001, <http://www.rfc-editor.org/info/rfc3042>.
[RFC3124] Balakrishnan, H. and S. Seshan, "The Congestion Manager", RFC 3124, June 2001, <http://www.rfc-editor.org/info/rfc3124>.
[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, <http://www.rfc-editor.org/info/rfc3135>.
[RFC3150] Dawkins, S., Montenegro, G., Kojo, M., and V. Magret, "End-to-end Performance Implications of Slow Links", BCP 48, RFC 3150, July 2001, <http://www.rfc-editor.org/info/rfc3150>.
[RFC3155] Dawkins, S., Montenegro, G., Kojo, M., Magret, V., and N. Vaidya, "End-to-end Performance Implications of Links with Errors", BCP 50, RFC 3155, August 2001, <http://www.rfc-editor.org/info/rfc3155>.
[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition of Explicit Congestion Notification (ECN) to IP", RFC 3168, September 2001, <http://www.rfc-editor.org/info/rfc3168>.
[RFC3360] Floyd, S., "Inappropriate TCP Resets Considered Harmful", BCP 60, RFC 3360, August 2002, <http://www.rfc-editor.org/info/rfc3360>.
[RFC3366] Fairhurst, G. and L. Wood, "Advice to link designers on link Automatic Repeat reQuest (ARQ)", BCP 62, RFC 3366, August 2002, <http://www.rfc-editor.org/info/rfc3366>.
[RFC3390] Allman, M., Floyd, S., and C. Partridge, "Increasing TCP's Initial Window", RFC 3390, October 2002, <http://www.rfc-editor.org/info/rfc3390>.
[RFC3439] Bush, R. and D. Meyer, "Some Internet Architectural Guidelines and Philosophy", RFC 3439, December 2002, <http://www.rfc-editor.org/info/rfc3439>.
[RFC3449] Balakrishnan, H., Padmanabhan, V., Fairhurst, G., and M. Sooriyabandara, "TCP Performance Implications of Network Path Asymmetry", BCP 69, RFC 3449, December 2002, <http://www.rfc-editor.org/info/rfc3449>.
[RFC3465] Allman, M., "TCP Congestion Control with Appropriate Byte Counting (ABC)", RFC 3465, February 2003, <http://www.rfc-editor.org/info/rfc3465>.
[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, <http://www.rfc-editor.org/info/rfc3481>.
[RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W. Stevens, "Basic Socket Interface Extensions for IPv6", RFC 3493, February 2003, <http://www.rfc-editor.org/info/rfc3493>.
[RFC3522] Ludwig, R. and M. Meyer, "The Eifel Detection Algorithm for TCP", RFC 3522, April 2003, <http://www.rfc-editor.org/info/rfc3522>.
[RFC3540] Spring, N., Wetherall, D., and D. Ely, "Robust Explicit Congestion Notification (ECN) Signaling with Nonces", RFC 3540, June 2003, <http://www.rfc-editor.org/info/rfc3540>.
[RFC3649] Floyd, S., "HighSpeed TCP for Large Congestion Windows", RFC 3649, December 2003, <http://www.rfc-editor.org/info/rfc3649>.
[RFC3708] Blanton, E. and M. Allman, "Using TCP Duplicate Selective Acknowledgement (DSACKs) and Stream Control Transmission Protocol (SCTP) Duplicate Transmission Sequence Numbers (TSNs) to Detect Spurious Retransmissions", RFC 3708, February 2004, <http://www.rfc-editor.org/info/rfc3708>.
[RFC3742] Floyd, S., "Limited Slow-Start for TCP with Large Congestion Windows", RFC 3742, March 2004, <http://www.rfc-editor.org/info/rfc3742>.
[RFC3819] Karn, P., Bormann, C., Fairhurst, G., Grossman, D., Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. Wood, "Advice for Internet Subnetwork Designers", BCP 89, RFC 3819, July 2004, <http://www.rfc-editor.org/info/rfc3819>.
[RFC4015] Ludwig, R. and A. Gurtov, "The Eifel Response Algorithm for TCP", RFC 4015, February 2005, <http://www.rfc-editor.org/info/rfc4015>.
[RFC4022] Raghunarayan, R., "Management Information Base for the Transmission Control Protocol (TCP)", RFC 4022, March 2005, <http://www.rfc-editor.org/info/rfc4022>.
[RFC4653] Bhandarkar, S., Reddy, A., Allman, M., and E. Blanton, "Improving the Robustness of TCP to Non-Congestion Events", RFC 4653, August 2006, <http://www.rfc-editor.org/info/rfc4653>.
[RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, ICMPv6, UDP, and TCP Headers", RFC 4727, November 2006, <http://www.rfc-editor.org/info/rfc4727>.
[RFC4774] Floyd, S., "Specifying Alternate Semantics for the Explicit Congestion Notification (ECN) Field", BCP 124, RFC 4774, November 2006, <http://www.rfc-editor.org/info/rfc4774>.
[RFC4782] Floyd, S., Allman, M., Jain, A., and P. Sarolahti, "Quick-Start for TCP and IP", RFC 4782, January 2007, <http://www.rfc-editor.org/info/rfc4782>.
[RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU Discovery", RFC 4821, March 2007, <http://www.rfc-editor.org/info/rfc4821>.
[RFC4898] Mathis, M., Heffner, J., and R. Raghunarayan, "TCP Extended Statistics MIB", RFC 4898, May 2007, <http://www.rfc-editor.org/info/rfc4898>.
[RFC4953] Touch, J., "Defending TCP Against Spoofing Attacks", RFC 4953, July 2007, <http://www.rfc-editor.org/info/rfc4953>.

10.2. Informative References

Okay bestie, this is the informative references list, aka the whole TCP drama hall of fame 💅✨ Every single one is spelled out below, exactly as written.

[RFC4987] Eddy, W., "TCP SYN Flooding Attacks and Common Mitigations", RFC 4987, August 2007, <http://www.rfc-editor.org/info/rfc4987>.
[RFC5033] Floyd, S. and M. Allman, "Specifying New Congestion Control Algorithms", BCP 133, RFC 5033, August 2007, <http://www.rfc-editor.org/info/rfc5033>.
[RFC5166] Floyd, S., "Metrics for the Evaluation of Congestion Control Mechanisms", RFC 5166, March 2008, <http://www.rfc-editor.org/info/rfc5166>.
[RFC5461] Gont, F., "TCP's Reaction to Soft Errors", RFC 5461, February 2009, <http://www.rfc-editor.org/info/rfc5461>.
[RFC5482] Eggert, L. and F. Gont, "TCP User Timeout Option", RFC 5482, March 2009, <http://www.rfc-editor.org/info/rfc5482>.
[RFC5562] Kuzmanovic, A., Mondal, A., Floyd, S., and K. Ramakrishnan, "Adding Explicit Congestion Notification (ECN) Capability to TCP's SYN/ACK Packets", RFC 5562, June 2009, <http://www.rfc-editor.org/info/rfc5562>.
[RFC5681] Allman, M., Paxson, V., and E. Blanton, "TCP Congestion Control", RFC 5681, September 2009, <http://www.rfc-editor.org/info/rfc5681>.
[RFC5682] Sarolahti, P., Kojo, M., Yamamoto, K., and M. Hata, "Forward RTO-Recovery (F-RTO): An Algorithm for Detecting Spurious Retransmission Timeouts with TCP", RFC 5682, September 2009, <http://www.rfc-editor.org/info/rfc5682>.
[RFC5690] Floyd, S., Arcia, A., Ros, D., and J. Iyengar, "Adding Acknowledgement Congestion Control to TCP", RFC 5690, February 2010, <http://www.rfc-editor.org/info/rfc5690>.
[RFC5783] Welzl, M. and W. Eddy, "Congestion Control in the RFC Series", RFC 5783, February 2010, <http://www.rfc-editor.org/info/rfc5783>.
[RFC5827] Allman, M., Avrachenkov, K., Ayesta, U., Blanton, J., and P. Hurtig, "Early Retransmit for TCP and Stream Control Transmission Protocol (SCTP)", RFC 5827, May 2010, <http://www.rfc-editor.org/info/rfc5827>.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP Authentication Option", RFC 5925, June 2010, <http://www.rfc-editor.org/info/rfc5925>.
[RFC5926] Lebovitz, G. and E. Rescorla, "Cryptographic Algorithms for the TCP Authentication Option (TCP-AO)", RFC 5926, June 2010, <http://www.rfc-editor.org/info/rfc5926>.
[RFC5927] Gont, F., "ICMP Attacks against TCP", RFC 5927, July 2010, <http://www.rfc-editor.org/info/rfc5927>.
[RFC5961] Ramaiah, A., Stewart, R., and M. Dalal, "Improving TCP's Robustness to Blind In-Window Attacks", RFC 5961, August 2010, <http://www.rfc-editor.org/info/rfc5961>.
[RFC6013] Simpson, W., "TCP Cookie Transactions (TCPCT)", RFC 6013, January 2011, <http://www.rfc-editor.org/info/rfc6013>.
[RFC6056] Larsen, M. and F. Gont, "Recommendations for Transport-Protocol Port Randomization", BCP 156, RFC 6056, January 2011, <http://www.rfc-editor.org/info/rfc6056>.
[RFC6069] Zimmermann, A. and A. Hannemann, "Making TCP More Robust to Long Connectivity Disruptions (TCP-LCD)", RFC 6069, December 2010, <http://www.rfc-editor.org/info/rfc6069>.
[RFC6077] Papadimitriou, D., Welzl, M., Scharf, M., and B. Briscoe, "Open Research Issues in Internet Congestion Control", RFC 6077, February 2011, <http://www.rfc-editor.org/info/rfc6077>.
[RFC6093] Gont, F. and A. Yourtchenko, "On the Implementation of the TCP Urgent Mechanism", RFC 6093, January 2011, <http://www.rfc-editor.org/info/rfc6093>.
[RFC6181] Bagnulo, M., "Threat Analysis for TCP Extensions for Multipath Operation with Multiple Addresses", RFC 6181, March 2011, <http://www.rfc-editor.org/info/rfc6181>.
[RFC6182] Ford, A., Raiciu, C., Handley, M., Barre, S., and J. Iyengar, "Architectural Guidelines for Multipath TCP Development", RFC 6182, March 2011, <http://www.rfc-editor.org/info/rfc6182>.
[RFC6191] Gont, F., "Reducing the TIME-WAIT State Using TCP Timestamps", BCP 159, RFC 6191, April 2011, <http://www.rfc-editor.org/info/rfc6191>.
[RFC6247] Eggert, L., "Moving the Undeployed TCP Extensions RFC 1072, RFC 1106, RFC 1110, RFC 1145, RFC 1146, RFC 1379, RFC 1644, and RFC 1693 to Historic Status", RFC 6247, May 2011, <http://www.rfc-editor.org/info/rfc6247>.
[RFC6298] Paxson, V., Allman, M., Chu, J., and M. Sargent, "Computing TCP's Retransmission Timer", RFC 6298, June 2011, <http://www.rfc-editor.org/info/rfc6298>.
[RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S. Cheshire, "Internet Assigned Numbers Authority (IANA) Procedures for the Management of the Service Name and Transport Protocol Port Number Registry", BCP 165, RFC 6335, August 2011, <http://www.rfc-editor.org/info/rfc6335>.
[RFC6349] Constantine, B., Forget, G., Geib, R., and R. Schrage, "Framework for TCP Throughput Testing", RFC 6349, August 2011, <http://www.rfc-editor.org/info/rfc6349>.
[RFC6356] Raiciu, C., Handley, M., and D. Wischik, "Coupled Congestion Control for Multipath Transport Protocols", RFC 6356, October 2011, <http://www.rfc-editor.org/info/rfc6356>.
[RFC6429] Bashyam, M., Jethanandani, M., and A. Ramaiah, "TCP Sender Clarification for Persist Condition", RFC 6429, December 2011, <http://www.rfc-editor.org/info/rfc6429>.
[RFC6528] Gont, F. and S. Bellovin, "Defending against Sequence Number Attacks", RFC 6528, February 2012, <http://www.rfc-editor.org/info/rfc6528>.
[RFC6582] Henderson, T., Floyd, S., Gurtov, A., and Y. Nishida, "The NewReno Modification to TCP's Fast Recovery Algorithm", RFC 6582, April 2012, <http://www.rfc-editor.org/info/rfc6582>.
[RFC6633] Gont, F., "Deprecation of ICMP Source Quench Messages", RFC 6633, May 2012, <http://www.rfc-editor.org/info/rfc6633>.
[RFC6675] Blanton, E., Allman, M., Wang, L., Jarvinen, I., Kojo, M., and Y. Nishida, "A Conservative Loss Recovery Algorithm Based on Selective Acknowledgment (SACK) for TCP", RFC 6675, August 2012, <http://www.rfc-editor.org/info/rfc6675>.
[RFC6691] Borman, D., "TCP Options and Maximum Segment Size (MSS)", RFC 6691, July 2012, <http://www.rfc-editor.org/info/rfc6691>.
[RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure, "TCP Extensions for Multipath Operation with Multiple Addresses", RFC 6824, January 2013, <http://www.rfc-editor.org/info/rfc6824>.
[RFC6846] Pelletier, G., Sandlund, K., Jonsson, L-E., and M. West, "RObust Header Compression (ROHC): A Profile for TCP/IP (ROHC-TCP)", RFC 6846, January 2013, <http://www.rfc-editor.org/info/rfc6846>.
[RFC6897] Scharf, M. and A. Ford, "Multipath TCP (MPTCP) Application Interface Considerations", RFC 6897, March 2013, <http://www.rfc-editor.org/info/rfc6897>.
[RFC6928] Chu, J., Dukkipati, N., Cheng, Y., and M. Mathis, "Increasing TCP's Initial Window", RFC 6928, April 2013, <http://www.rfc-editor.org/info/rfc6928>.
[RFC6937] Mathis, M., Dukkipati, N., and Y. Cheng, "Proportional Rate Reduction for TCP", RFC 6937, May 2013, <http://www.rfc-editor.org/info/rfc6937>.
[RFC6994] Touch, J., "Shared Use of Experimental TCP Options", RFC 6994, August 2013, <http://www.rfc-editor.org/info/rfc6994>.
[RFC7323] Borman, D., Braden, B., Jacobson, V., and R. Scheffenegger, "TCP Extensions for High Performance", RFC 7323, September 2014, <http://www.rfc-editor.org/info/rfc7323>.
[RFC7413] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP Fast Open", RFC 7413, December 2014, <http://www.rfc-editor.org/info/rfc7413>.

That's the whole informative list, slay 🫶🌸

10.2. Informative References 📚

Okay, bestie, this is the background reading pile. These aren't required to implement anything, but they're where all the good history and context live 🧚

[CK73] Cerf, V. and R. Kahn, "Towards Protocols for Internetwork Communication", IFIP/TC6.1, NIC 18764, INWG 39, September 1973.
[CTCP] Sridharan, M., Tan, K., Bansal, D., and D. Thaler, "Compound TCP: A New TCP Congestion Control for High-Speed and Long Distance Networks", Work in Progress, draft-sridharan-tcpm-ctcp-02, November 2008. 🔥
[CUBIC] Rhee, I., Xu, L., and S. Ha, "CUBIC for Fast Long-Distance Networks", Work in Progress, draft-rhee-tcpm-cubic-02, August 2008. 🌈
[Errata] RFC Editor, "RFC Errata", <http://www.rfc-editor.org/errata.php>. 🩹
[HTCP] Leith, D., "H-TCP: TCP Congestion Control for High Bandwidth-Delay Product Paths", Work in Progress, draft-leith-tcp-htcp-06, April 2008. 💜
[JK92] Jacobson, V. and M. Karels, "Congestion Avoidance and Control", November 1992, <ftp://ftp.ee.lbl.gov/papers/congavoid.ps.Z>. 🍓
[Jac88] Jacobson, V., "Congestion Avoidance and Control", ACM SIGCOMM 1988 Proceedings, in ACM Computer Communication Review, 18 (4), pp. 314-329, August 1988. 👑
[Jacobson] Jacobson, V., "TCP-IP Mailing List", Article 167 of comp.protocols.tcp-ip, March 1988, <ftp://ftp.ee.lbl.gov/email/vanj.88mar10.txt>. 🦋
[KP87] Karn, P. and C. Partridge, "Round Trip Time Estimation", ACM SIGCOMM 1987 Proceedings, in ACM Computer Communication Review, 17 (5), pp. 2-7, August 1987. ⭐
[MAF04] Medina, A., Allman, M., and S. Floyd, "Measuring the Evolution of Transport Protocols in the Internet", ACM Computer Communication Review, 35 (2), April 2005. 🫶
[MM96] Mathis, M. and J. Mahdavi, "Forward Acknowledgement: Refining TCP Congestion Control", ACM SIGCOMM 1996 Proceedings, in ACM Computer Communication Review 26 (4), pp. 281-292, October 1996. 🌸
[RFC1016] Prue, W. and J. Postel, "Something a host could do with source quench: The Source Quench Introduced Delay (SQuID)", RFC 1016, July 1987, <http://www.rfc-editor.org/info/rfc1016>. 🎀
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996, <http://www.rfc-editor.org/info/rfc2026>. 🧚
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>. 💅
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers", RFC 2474, December 1998, <http://www.rfc-editor.org/info/rfc2474>. ✨
[RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P. Conrad, "Stream Control Transmission Protocol (SCTP) Partial Reliability Extension", RFC 3758, May 2004, <http://www.rfc-editor.org/info/rfc3758>. 🌈
[RFC4340] Kohler, E., Handley, M., and S. Floyd, "Datagram Congestion Control Protocol (DCCP)", RFC 4340, March 2006, <http://www.rfc-editor.org/info/rfc4340>. 🦋
[RFC4341] Floyd, S. and E. Kohler, "Profile for Datagram Congestion Control Protocol (DCCP) Congestion Control ID 2: TCP-like Congestion Control", RFC 4341, March 2006, <http://www.rfc-editor.org/info/rfc4341>. 💜
[RFC6115] Li, T., "Recommendation for a Routing Architecture", RFC 6115, February 2011, <http://www.rfc-editor.org/info/rfc6115>. 🍓
[SCWA99] Savage, S., Cardwell, N., Wetherall, D., and T. Anderson, "TCP Congestion Control with a Misbehaving Receiver", ACM Computer Communication Review, 29 (5), pp. 71-78, October 1999. 🔥

Acknowledgments 🫶

Okay, the shoutouts! ✨ This document grew out of a discussion on the end2end-interest mailing list, which is the public list of the End-to-End Research Group of the IRTF. It kept growing under the IETF's TCP Maintenance and Minor Extensions (TCPM) working group. Big thanks to Mark Allman, Yuchung Cheng, Ted Faber, Gorry Fairhurst, Sally Floyd, Janardhan Iyengar, Reiner Ludwig, Pekka Savola, and Joe Touch for their contributions, in particular. 💖 Keith McCloghrie also gave some super useful notes and clarification on the various MIB-related RFCs. Legends only 👑

Authors' Addresses 🦋

Here's who to reach out to, bestie 💌

Martin Duke

Martin Duke
F5 Networks
401 Elliott Ave W
Seattle, WA  98119
United States

Phone: 206-272-7537
EMail: m.duke@f5.com

Robert Braden

Robert Braden
USC Information Sciences Institute
Marina del Rey, CA  90292-6695
United States

Phone: 310-448-9173
EMail: braden@isi.edu

Wesley M. Eddy

Wesley M. Eddy
MTI Systems
18013 Cleveland Parkway
Suite 170
Cleveland, OH  44135
United States

Phone: 216-433-6682
EMail: wes@mti-systems.com

Ethan Blanton

Ethan Blanton
Interrupt Sciences

EMail: elb@interruptsciences.com

Alexander Zimmermann

Alexander Zimmermann
NetApp, Inc.
Sonnenallee 1
Kirchheim  85551
Germany

Phone: +49 89 900594712
EMail: alexander.zimmermann@netapp.com

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