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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Protocol ossification</span></span>
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<p><b>Protocol ossification</b> is the loss of flexibility, <a href="Extensibility" title="Extensibility">extensibility</a> and evolvability of <a href="Network_protocols" class="mw-redirect" title="Network protocols">network protocols</a>. This is largely due to <a href="Middlebox" title="Middlebox">middleboxes</a> that are sensitive to the <a href="Wire_image_(networking)" class="mw-redirect" title="Wire image (networking)">wire image</a> of the protocol, and which can interrupt or interfere with messages that are valid but which the middlebox does not correctly recognise. This is a violation of the <a href="End-to-end_principle" title="End-to-end principle">end-to-end principle</a>. Secondary causes include inflexibility in endpoint implementations of protocols.
</p><p>Ossification is a major issue in <a href="Internet" title="Internet">Internet</a> protocol design and deployment, as it can prevent new protocols or extensions from being deployed on the Internet, or place strictures on the design of new protocols; new protocols may have to be <a href="Encapsulation_(networking)" title="Encapsulation (networking)">encapsulated</a> in an already-deployed protocol or mimic the wire image of another protocol. Because of ossification, the <a href="Transmission_Control_Protocol" title="Transmission Control Protocol">Transmission Control Protocol</a> (TCP) and <a href="User_Datagram_Protocol" title="User Datagram Protocol">User Datagram Protocol</a> (UDP) are the only practical choices for <a href="Transport_protocol" class="mw-redirect" title="Transport protocol">transport protocols</a> on the Internet, and TCP itself has significantly ossified, making extension or modification of the protocol difficult.
</p><p>Recommended methods of preventing ossification include <a href="Encrypting" class="mw-redirect" title="Encrypting">encrypting</a> protocol metadata, and ensuring that extension points are exercised and wire image variability is exhibited as fully as possible; remedying existing ossification requires coordination across protocol participants. <a href="QUIC" title="QUIC">QUIC</a> is the first <a href="IETF" class="mw-redirect" title="IETF">IETF</a> transport protocol to have been designed with deliberate anti-ossification properties.
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<div class="mw-heading mw-heading2"><h2 id="History">History</h2></div>
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<p>Significant ossification had set in on the <a href="Internet" title="Internet">Internet</a> by 2005, with analyses of the problem also being published in that year;<sup id="cite_ref-FOOTNOTEAmmar201857-58_1-0" class="reference"><a href="#cite_note-FOOTNOTEAmmar201857-58-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> <a href="#CITEREFAmmar2018">Ammar (2018)</a> suggests that ossification was a consequence of the Internet attaining global scale and becoming the primary communication network.<sup id="cite_ref-FOOTNOTEAmmar201859_2-0" class="reference"><a href="#cite_note-FOOTNOTEAmmar201859-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>
</p><p><a href="Multipath_TCP" title="Multipath TCP">Multipath TCP</a> was the first extension to a core Internet protocol to deeply confront protocol ossification during its design.<sup id="cite_ref-FOOTNOTERaiciuPaaschBarreFord20121_3-0" class="reference"><a href="#cite_note-FOOTNOTERaiciuPaaschBarreFord20121-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup>
</p><p>The IETF created the Transport Services (taps) working group in 2014.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> It has a mandate to mitigate ossification at the <a href="Transport_protocol" class="mw-redirect" title="Transport protocol">transport protocol</a> layer.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup>
</p><p><a href="QUIC" title="QUIC">QUIC</a> is the first <a href="IETF" class="mw-redirect" title="IETF">IETF</a> transport protocol to deliberately minimise its wire image to avoid ossification.<sup id="cite_ref-FOOTNOTETrammellKuehlewind20192_6-0" class="reference"><a href="#cite_note-FOOTNOTETrammellKuehlewind20192-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup>
</p><p>The <a href="Internet_Architecture_Board" title="Internet Architecture Board">Internet Architecture Board</a> identified design considerations around the exposure of protocol information to network elements as a "developing field" in 2023.<sup id="cite_ref-FOOTNOTEArkkoHardiePaulyKühlewind20233._Further_Work_7-0" class="reference"><a href="#cite_note-FOOTNOTEArkkoHardiePaulyKühlewind20233._Further_Work-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup>
</p>
<div class="mw-heading mw-heading2"><h2 id="Causes">Causes</h2></div>
<p>The primary cause of protocol ossification is <a href="Middlebox" title="Middlebox">middlebox</a> interference,<sup id="cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017619_8-0" class="reference"><a href="#cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017619-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> invalidating the <a href="End-to-end_principle" title="End-to-end principle">end-to-end principle</a>.<sup id="cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017620_9-0" class="reference"><a href="#cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017620-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> Middleboxes may entirely block unknown protocols or unrecognised extensions to known protocols, interfere with extension or feature negotiation, or perform more invasive modification of protocol metadata.<sup id="cite_ref-FOOTNOTEEdelineDonnet2019171_10-0" class="reference"><a href="#cite_note-FOOTNOTEEdelineDonnet2019171-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> Not all middlebox modifications are necessarily ossifying; of those which are potentially harmful, they are disproportionately towards the network edge.<sup id="cite_ref-FOOTNOTEEdelineDonnet2019173-175_11-0" class="reference"><a href="#cite_note-FOOTNOTEEdelineDonnet2019173-175-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> Middleboxes are deployed by network operators unilaterally to solve specific problems,<sup id="cite_ref-FOOTNOTEEdelineDonnet2019169_12-0" class="reference"><a href="#cite_note-FOOTNOTEEdelineDonnet2019169-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> including performance optimisation, security requirements (e.g., firewalls), <a href="Network_address_translation" title="Network address translation">network address translation</a> or enhancing control of networks.<sup id="cite_ref-FOOTNOTEHondaNishidaRaiciuGreenhalgh20111_13-0" class="reference"><a href="#cite_note-FOOTNOTEHondaNishidaRaiciuGreenhalgh20111-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> These middlebox deployments provide localised short-term utility but degrade the global long-term evolvability of the Internet in a manifestation of the <a href="Tragedy_of_the_commons" title="Tragedy of the commons">tragedy of the commons</a>.<sup id="cite_ref-FOOTNOTEEdelineDonnet2019169_12-1" class="reference"><a href="#cite_note-FOOTNOTEEdelineDonnet2019169-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup>
</p><p>Changes to a protocol must be tolerated by all on-path intermediaries; if wide Internet deployment of the change is desired, then this extends to a large portion of intermediaries on the Internet. A middlebox must tolerate widely used protocols as they were being used at the time of its deployment, but is liable not to tolerate new protocols or changes to extant ones, effectively creating a <a href="Vicious_cycle" class="mw-redirect" title="Vicious cycle">vicious cycle</a> as novel <a href="Wire_image_(networking)" class="mw-redirect" title="Wire image (networking)">wire images</a> cannot gain wide enough deployment to make middleboxes tolerate the new wire image across the entire Internet.<sup id="cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017620_9-1" class="reference"><a href="#cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017620-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> Even all participants tolerating the protocol is no guarantee of use: in the absence of a negotiation or discovery mechanism, the endpoints may default to a protocol that is considered more reliable.<sup id="cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017621_14-0" class="reference"><a href="#cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017621-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup>
</p><p>Beyond middleboxes, ossification can also be caused by insufficient flexibility within the endpoint's implementation. <a href="Operating_system_kernels" class="mw-redirect" title="Operating system kernels">Operating system kernels</a> are slow to change and deploy,<sup id="cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017621_14-1" class="reference"><a href="#cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017621-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> and protocols implemented in hardware can also inappropriately fix protocol details.<sup id="cite_ref-FOOTNOTECorbet2015_15-0" class="reference"><a href="#cite_note-FOOTNOTECorbet2015-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> A widely used <a href="Application_programming_interface" class="mw-redirect" title="Application programming interface">application programming interface</a> (API) that makes assumptions about the operation of underlying protocols can hinder the deployment of protocols that do not share those assumptions.<sup id="cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017620_9-2" class="reference"><a href="#cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017620-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup>
</p>
<div class="mw-heading mw-heading2"><h2 id="Prevention_and_remediation">Prevention and remediation</h2></div>
<p>The <a href="Internet_Architecture_Board" title="Internet Architecture Board">Internet Architecture Board</a> recommended in 2019 that implicit signals to observers should be replaced with signals deliberately intended for the consumption of those observers, and signals not intended for their consumption should not be available to them (e.g., by encryption); and also that the protocol metadata should be <a href="Message_authentication" title="Message authentication">integrity protected</a> so that it cannot be modified by middleboxes.<sup id="cite_ref-FOOTNOTEHardie20197-8_16-0" class="reference"><a href="#cite_note-FOOTNOTEHardie20197-8-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> However, even fully encrypted metadata may not entirely prevent ossification in the network, as the wire image of a protocol can still show patterns that come to be relied upon.<sup id="cite_ref-FOOTNOTEFairhurstPerkins20217._Conclusions_17-0" class="reference"><a href="#cite_note-FOOTNOTEFairhurstPerkins20217._Conclusions-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> Network operators use metadata for a variety of benign management purposes,<sup id="cite_ref-FOOTNOTEFairhurstPerkins20212._Current_Uses_of_Transport_Headers_within_the_Network_18-0" class="reference"><a href="#cite_note-FOOTNOTEFairhurstPerkins20212._Current_Uses_of_Transport_Headers_within_the_Network-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> and Internet research is also informed by data gathered from protocol metadata;<sup id="cite_ref-FOOTNOTEFairhurstPerkins20213._Research,_Development,_and_Deployment_19-0" class="reference"><a href="#cite_note-FOOTNOTEFairhurstPerkins20213._Research,_Development,_and_Deployment-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> a protocol's designer must balance ossification resistance against observability for operational or research needs.<sup id="cite_ref-FOOTNOTEFairhurstPerkins20217._Conclusions_17-1" class="reference"><a href="#cite_note-FOOTNOTEFairhurstPerkins20217._Conclusions-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> <a href="#CITEREFArkkoHardiePaulyKühlewind2023">Arkko et al. (2023)</a> provides further guidance on these considerations: disclosure of information by a protocol to the network should be intentional,<sup id="cite_ref-FOOTNOTEArkkoHardiePaulyKühlewind20232.1._Intentional_Distribution_20-0" class="reference"><a href="#cite_note-FOOTNOTEArkkoHardiePaulyKühlewind20232.1._Intentional_Distribution-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> performed with the agreement of both recipient and sender,<sup id="cite_ref-FOOTNOTEArkkoHardiePaulyKühlewind20232.2._Control_of_the_Distribution_of_Information_21-0" class="reference"><a href="#cite_note-FOOTNOTEArkkoHardiePaulyKühlewind20232.2._Control_of_the_Distribution_of_Information-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> authenticated to the degree possible and necessary,<sup id="cite_ref-FOOTNOTEArkkoHardiePaulyKühlewind20232.3._Protecting_Information_and_Authentication_22-0" class="reference"><a href="#cite_note-FOOTNOTEArkkoHardiePaulyKühlewind20232.3._Protecting_Information_and_Authentication-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> only acted upon to the degree of its trustworthiness,<sup id="cite_ref-FOOTNOTEArkkoHardiePaulyKühlewind20232.5._Limiting_Impact_of_Information_23-0" class="reference"><a href="#cite_note-FOOTNOTEArkkoHardiePaulyKühlewind20232.5._Limiting_Impact_of_Information-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> and minimised and provided to a minimum number of entities.<sup id="cite_ref-FOOTNOTEArkkoHardiePaulyKühlewind20232.4._Minimize_Information_24-0" class="reference"><a href="#cite_note-FOOTNOTEArkkoHardiePaulyKühlewind20232.4._Minimize_Information-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-FOOTNOTEArkkoHardiePaulyKühlewind20232.6._Minimum_Set_of_Entities_25-0" class="reference"><a href="#cite_note-FOOTNOTEArkkoHardiePaulyKühlewind20232.6._Minimum_Set_of_Entities-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup>
</p><p>Active use of extension points is required if they are not to ossify.<sup id="cite_ref-FOOTNOTEThomsonPauly20213._Active_Use_26-0" class="reference"><a href="#cite_note-FOOTNOTEThomsonPauly20213._Active_Use-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> Reducing the number of extension points, documenting invariants that protocol participants can rely on as opposed to incidental details that must not be relied upon, and prompt detection of issues in deployed systems can assist in ensuring active use.<sup id="cite_ref-FOOTNOTEThomsonPauly20214._Complementary_Techniques_27-0" class="reference"><a href="#cite_note-FOOTNOTEThomsonPauly20214._Complementary_Techniques-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> However, even active use may only exercise a narrow portion of the protocol and ossification can still occur in the parts that remain invariant in practice despite theoretical variability.<sup id="cite_ref-FOOTNOTEThomsonPauly20213.1._Dependency_Is_Better_28-0" class="reference"><a href="#cite_note-FOOTNOTEThomsonPauly20213.1._Dependency_Is_Better-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-FOOTNOTETrammellKuehlewind20197_29-0" class="reference"><a href="#cite_note-FOOTNOTETrammellKuehlewind20197-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> "Greasing" an extension point, where some implementations indicate support for non-existent extensions, can ensure that actually-existent-but-unrecognised extensions are tolerated (cf. <a href="Chaos_engineering" title="Chaos engineering">chaos engineering</a>).<sup id="cite_ref-FOOTNOTEThomsonPauly20213.3._Falsifying_Active_Use_30-0" class="reference"><a href="#cite_note-FOOTNOTEThomsonPauly20213.3._Falsifying_Active_Use-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> <a href="HTTP_headers" class="mw-redirect" title="HTTP headers">HTTP headers</a> are an example of an extension point that has successfully avoided significant ossification, as participants will generally ignore unrecognised headers.<sup id="cite_ref-FOOTNOTEThomsonPauly20213.4._Examples_of_Active_Use_31-0" class="reference"><a href="#cite_note-FOOTNOTEThomsonPauly20213.4._Examples_of_Active_Use-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup>
</p><p>A new protocol may be designed to mimic the wire image of an existing ossified protocol;<sup id="cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017623_32-0" class="reference"><a href="#cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017623-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> alternatively, a new protocol may be <a href="Encapsulation_(networking)" title="Encapsulation (networking)">encapsulated</a> within an existing, tolerated protocol. A disadvantage of encapsulation is that there is typically overhead and redundant work (e.g., outer checksums made redundant by inner integrity checks).<sup id="cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017623-4_33-0" class="reference"><a href="#cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017623-4-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup>
</p><p>Besides middleboxes, other sources of ossification can also be resisted. <a href="User-space" class="mw-redirect" title="User-space">User-space</a> implementation of protocols can lead to more rapid evolution. If the new protocol is encapsulated in UDP, then user-space implementation is possible.<sup id="cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017630_34-0" class="reference"><a href="#cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017630-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-FOOTNOTECorbet2016_35-0" class="reference"><a href="#cite_note-FOOTNOTECorbet2016-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> Where support for protocols is uncertain, participants may simultaneously try alternative protocols, at the cost of increasing the amount of data sent.<sup id="cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017629_36-0" class="reference"><a href="#cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017629-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup>
</p><p>With sufficient effort and coordination, ossification can be directly reversed. A <a href="Flag_day_(computing)" title="Flag day (computing)">flag day</a>, where protocol participants make changes in concert, can break the vicious cycle and establish active use. This approach was used to deploy <a href="EDNS" class="mw-redirect" title="EDNS">EDNS</a>, which had formerly not been tolerated by servers.<sup id="cite_ref-FOOTNOTEThomsonPauly20213.5._Restoring_Active_Use_37-0" class="reference"><a href="#cite_note-FOOTNOTEThomsonPauly20213.5._Restoring_Active_Use-37"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup>
</p>
<div class="mw-heading mw-heading2"><h2 id="Examples">Examples</h2></div>
<p>The <a href="Transmission_Control_Protocol" title="Transmission Control Protocol">Transmission Control Protocol</a> has suffered from ossification.<sup id="cite_ref-FOOTNOTEThomsonPauly2021A.5._TCP_38-0" class="reference"><a href="#cite_note-FOOTNOTEThomsonPauly2021A.5._TCP-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> One measurement found that a third of paths across the Internet encounter at least one intermediary that modifies TCP metadata, and 6.5% of paths encounter harmful ossifying effects from intermediaries.<sup id="cite_ref-FOOTNOTEEdelineDonnet2019175-176_39-0" class="reference"><a href="#cite_note-FOOTNOTEEdelineDonnet2019175-176-39"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> Extensions to TCP have been affected: the design of <a href="MPTCP" class="mw-redirect" title="MPTCP">MPTCP</a> was constrained by middlebox behaviour,<sup id="cite_ref-FOOTNOTERaiciuPaaschBarreFord20121_3-1" class="reference"><a href="#cite_note-FOOTNOTERaiciuPaaschBarreFord20121-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-FOOTNOTEHesmansDuchenePaaschDetal20131_40-0" class="reference"><a href="#cite_note-FOOTNOTEHesmansDuchenePaaschDetal20131-40"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> and the deployment of <a href="TCP_Fast_Open" title="TCP Fast Open">TCP Fast Open</a> has been likewise hindered.<sup id="cite_ref-FOOTNOTERybczyńska2020_41-0" class="reference"><a href="#cite_note-FOOTNOTERybczyńska2020-41"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-FOOTNOTEThomsonPauly2021A.5._TCP_38-1" class="reference"><a href="#cite_note-FOOTNOTEThomsonPauly2021A.5._TCP-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup>
</p><p>The <a href="Stream_Control_Transmission_Protocol" title="Stream Control Transmission Protocol">Stream Control Transmission Protocol</a> has been little-deployed on the Internet due to intolerance from middleboxes,<sup id="cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017620_9-3" class="reference"><a href="#cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017620-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> and also due to the very widespread <a href="BSD_sockets_API" class="mw-redirect" title="BSD sockets API">BSD sockets API</a> ill-fitting its capabilities.<sup id="cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017627_42-0" class="reference"><a href="#cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017627-42"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup> In practice, TCP and UDP are the only usable Internet <a href="Transport_protocol" class="mw-redirect" title="Transport protocol">transport protocols</a>.<sup id="cite_ref-FOOTNOTEMcQuistinPerkinsFayed20161_43-0" class="reference"><a href="#cite_note-FOOTNOTEMcQuistinPerkinsFayed20161-43"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup>
</p><p><a href="Transport_Layer_Security" title="Transport Layer Security">Transport Layer Security</a> (TLS) has experienced ossification. TLS was the original context for the introduction of greasing extension points. <a href="TLS_1.3" class="mw-redirect" title="TLS 1.3">TLS 1.3</a>, as originally designed, proved undeployable on the Internet: middleboxes had ossified the protocol's version parameter. This was discovered late in the protocol design process, during experimental deployments by <a href="Web_browsers" class="mw-redirect" title="Web browsers">web browsers</a>. As a result, version 1.3 mimics the wire image of version 1.2.<sup id="cite_ref-FOOTNOTESullivan2017_44-0" class="reference"><a href="#cite_note-FOOTNOTESullivan2017-44"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup>
</p><p><a href="QUIC" title="QUIC">QUIC</a> has been specifically designed to be deployable, evolvable and to have anti-ossification properties;<sup id="cite_ref-FOOTNOTECorbet2018_45-0" class="reference"><a href="#cite_note-FOOTNOTECorbet2018-45"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup> it is the first <a href="IETF" class="mw-redirect" title="IETF">IETF</a> transport protocol to deliberately minimise its wire image for these ends.<sup id="cite_ref-FOOTNOTETrammellKuehlewind20192_6-1" class="reference"><a href="#cite_note-FOOTNOTETrammellKuehlewind20192-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> It is greased,<sup id="cite_ref-FOOTNOTEThomsonPauly20213.3._Falsifying_Active_Use_30-1" class="reference"><a href="#cite_note-FOOTNOTEThomsonPauly20213.3._Falsifying_Active_Use-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> it has protocol invariants explicitly specified,<sup id="cite_ref-FOOTNOTEThomson20212._Fixed_Properties_of_All_QUIC_Versions_46-0" class="reference"><a href="#cite_note-FOOTNOTEThomson20212._Fixed_Properties_of_All_QUIC_Versions-46"><span class="cite-bracket">[</span>46<span class="cite-bracket">]</span></a></sup> it is encapsulated in UDP, and its protocol metadata is encrypted.<sup id="cite_ref-FOOTNOTECorbet2018_45-1" class="reference"><a href="#cite_note-FOOTNOTECorbet2018-45"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup> Still, applications using QUIC must be prepared to fall back to other protocols, as UDP is blocked by some middleboxes.<sup id="cite_ref-FOOTNOTEKühlewindTrammell20222._The_Necessity_of_Fallback_47-0" class="reference"><a href="#cite_note-FOOTNOTEKühlewindTrammell20222._The_Necessity_of_Fallback-47"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup>
</p>
<div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2></div>
<ul><li><a href="Backward_compatibility" title="Backward compatibility">Backward compatibility</a></li>
<li><a href="Collective_action_problem" title="Collective action problem">Collective action problem</a></li>
<li><a href="De_facto_standard" title="De facto standard"><i>De facto</i> standard</a></li>
<li><a href="Forward_compatibility" title="Forward compatibility">Forward compatibility</a></li>
<li><a href="Interoperability" title="Interoperability">Interoperability</a></li>
<li><a href="Hyrum's_law" class="mw-redirect" title="Hyrum's law">Hyrum's law</a></li>
<li><a href="Network_effect" title="Network effect">Network effect</a></li>
<li><a href="Robustness_principle" title="Robustness principle">Robustness principle</a></li>
<li><a href="Vendor_lock-in" title="Vendor lock-in">Vendor lock-in</a></li></ul>
<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>
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</style><div class="reflist">
<div class="mw-references-wrap mw-references-columns"><ol class="references">
<li id="cite_note-FOOTNOTEAmmar201857-58-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEAmmar201857-58_1-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFAmmar2018">Ammar 2018</a>, p. 57-58.</span>
</li>
<li id="cite_note-FOOTNOTEAmmar201859-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEAmmar201859_2-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFAmmar2018">Ammar 2018</a>, p. 59.</span>
</li>
<li id="cite_note-FOOTNOTERaiciuPaaschBarreFord20121-3"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTERaiciuPaaschBarreFord20121_3-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTERaiciuPaaschBarreFord20121_3-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFRaiciuPaaschBarreFord2012">Raiciu et al. 2012</a>, p. 1.</span>
</li>
<li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">
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/* end https://en.wikipedia.org/ */
</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://datatracker.ietf.org/wg/taps/history/">"Transport Services (taps) – Group history"</a>. <a href="IETF" class="mw-redirect" title="IETF">IETF</a>.</cite></span>
</li>
<li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/charter-ietf-taps/">"Transport Services – charter-ietf-taps-02"</a>. <a href="IETF" class="mw-redirect" title="IETF">IETF</a>.</cite></span>
</li>
<li id="cite_note-FOOTNOTETrammellKuehlewind20192-6"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTETrammellKuehlewind20192_6-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTETrammellKuehlewind20192_6-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFTrammellKuehlewind2019">Trammell & Kuehlewind 2019</a>, p. 2.</span>
</li>
<li id="cite_note-FOOTNOTEArkkoHardiePaulyKühlewind20233._Further_Work-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEArkkoHardiePaulyKühlewind20233._Further_Work_7-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFArkkoHardiePaulyKühlewind2023">Arkko et al. 2023</a>, 3. Further Work.</span>
</li>
<li id="cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017619-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017619_8-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFPapastergiouFairhurstRosBrunstrom2017">Papastergiou et al. 2017</a>, p. 619.</span>
</li>
<li id="cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017620-9"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017620_9-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017620_9-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017620_9-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017620_9-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFPapastergiouFairhurstRosBrunstrom2017">Papastergiou et al. 2017</a>, p. 620.</span>
</li>
<li id="cite_note-FOOTNOTEEdelineDonnet2019171-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEEdelineDonnet2019171_10-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFEdelineDonnet2019">Edeline & Donnet 2019</a>, p. 171.</span>
</li>
<li id="cite_note-FOOTNOTEEdelineDonnet2019173-175-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEEdelineDonnet2019173-175_11-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFEdelineDonnet2019">Edeline & Donnet 2019</a>, p. 173-175.</span>
</li>
<li id="cite_note-FOOTNOTEEdelineDonnet2019169-12"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTEEdelineDonnet2019169_12-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTEEdelineDonnet2019169_12-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFEdelineDonnet2019">Edeline & Donnet 2019</a>, p. 169.</span>
</li>
<li id="cite_note-FOOTNOTEHondaNishidaRaiciuGreenhalgh20111-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEHondaNishidaRaiciuGreenhalgh20111_13-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFHondaNishidaRaiciuGreenhalgh2011">Honda et al. 2011</a>, p. 1.</span>
</li>
<li id="cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017621-14"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017621_14-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017621_14-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFPapastergiouFairhurstRosBrunstrom2017">Papastergiou et al. 2017</a>, p. 621.</span>
</li>
<li id="cite_note-FOOTNOTECorbet2015-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTECorbet2015_15-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFCorbet2015">Corbet 2015</a>.</span>
</li>
<li id="cite_note-FOOTNOTEHardie20197-8-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEHardie20197-8_16-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFHardie2019">Hardie 2019</a>, p. 7-8.</span>
</li>
<li id="cite_note-FOOTNOTEFairhurstPerkins20217._Conclusions-17"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTEFairhurstPerkins20217._Conclusions_17-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTEFairhurstPerkins20217._Conclusions_17-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFFairhurstPerkins2021">Fairhurst & Perkins 2021</a>, 7. Conclusions.</span>
</li>
<li id="cite_note-FOOTNOTEFairhurstPerkins20212._Current_Uses_of_Transport_Headers_within_the_Network-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEFairhurstPerkins20212._Current_Uses_of_Transport_Headers_within_the_Network_18-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFFairhurstPerkins2021">Fairhurst & Perkins 2021</a>, 2. Current Uses of Transport Headers within the Network.</span>
</li>
<li id="cite_note-FOOTNOTEFairhurstPerkins20213._Research,_Development,_and_Deployment-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEFairhurstPerkins20213._Research,_Development,_and_Deployment_19-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFFairhurstPerkins2021">Fairhurst & Perkins 2021</a>, 3. Research, Development, and Deployment.</span>
</li>
<li id="cite_note-FOOTNOTEArkkoHardiePaulyKühlewind20232.1._Intentional_Distribution-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEArkkoHardiePaulyKühlewind20232.1._Intentional_Distribution_20-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFArkkoHardiePaulyKühlewind2023">Arkko et al. 2023</a>, 2.1. Intentional Distribution.</span>
</li>
<li id="cite_note-FOOTNOTEArkkoHardiePaulyKühlewind20232.2._Control_of_the_Distribution_of_Information-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEArkkoHardiePaulyKühlewind20232.2._Control_of_the_Distribution_of_Information_21-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFArkkoHardiePaulyKühlewind2023">Arkko et al. 2023</a>, 2.2. Control of the Distribution of Information.</span>
</li>
<li id="cite_note-FOOTNOTEArkkoHardiePaulyKühlewind20232.3._Protecting_Information_and_Authentication-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEArkkoHardiePaulyKühlewind20232.3._Protecting_Information_and_Authentication_22-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFArkkoHardiePaulyKühlewind2023">Arkko et al. 2023</a>, 2.3. Protecting Information and Authentication.</span>
</li>
<li id="cite_note-FOOTNOTEArkkoHardiePaulyKühlewind20232.5._Limiting_Impact_of_Information-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEArkkoHardiePaulyKühlewind20232.5._Limiting_Impact_of_Information_23-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFArkkoHardiePaulyKühlewind2023">Arkko et al. 2023</a>, 2.5. Limiting Impact of Information.</span>
</li>
<li id="cite_note-FOOTNOTEArkkoHardiePaulyKühlewind20232.4._Minimize_Information-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEArkkoHardiePaulyKühlewind20232.4._Minimize_Information_24-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFArkkoHardiePaulyKühlewind2023">Arkko et al. 2023</a>, 2.4. Minimize Information.</span>
</li>
<li id="cite_note-FOOTNOTEArkkoHardiePaulyKühlewind20232.6._Minimum_Set_of_Entities-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEArkkoHardiePaulyKühlewind20232.6._Minimum_Set_of_Entities_25-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFArkkoHardiePaulyKühlewind2023">Arkko et al. 2023</a>, 2.6. Minimum Set of Entities.</span>
</li>
<li id="cite_note-FOOTNOTEThomsonPauly20213._Active_Use-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEThomsonPauly20213._Active_Use_26-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFThomsonPauly2021">Thomson & Pauly 2021</a>, 3. Active Use.</span>
</li>
<li id="cite_note-FOOTNOTEThomsonPauly20214._Complementary_Techniques-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEThomsonPauly20214._Complementary_Techniques_27-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFThomsonPauly2021">Thomson & Pauly 2021</a>, 4. Complementary Techniques.</span>
</li>
<li id="cite_note-FOOTNOTEThomsonPauly20213.1._Dependency_Is_Better-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEThomsonPauly20213.1._Dependency_Is_Better_28-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFThomsonPauly2021">Thomson & Pauly 2021</a>, 3.1. Dependency Is Better.</span>
</li>
<li id="cite_note-FOOTNOTETrammellKuehlewind20197-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTETrammellKuehlewind20197_29-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFTrammellKuehlewind2019">Trammell & Kuehlewind 2019</a>, p. 7.</span>
</li>
<li id="cite_note-FOOTNOTEThomsonPauly20213.3._Falsifying_Active_Use-30"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTEThomsonPauly20213.3._Falsifying_Active_Use_30-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTEThomsonPauly20213.3._Falsifying_Active_Use_30-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFThomsonPauly2021">Thomson & Pauly 2021</a>, 3.3. Falsifying Active Use.</span>
</li>
<li id="cite_note-FOOTNOTEThomsonPauly20213.4._Examples_of_Active_Use-31"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEThomsonPauly20213.4._Examples_of_Active_Use_31-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFThomsonPauly2021">Thomson & Pauly 2021</a>, 3.4. Examples of Active Use.</span>
</li>
<li id="cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017623-32"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017623_32-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFPapastergiouFairhurstRosBrunstrom2017">Papastergiou et al. 2017</a>, p. 623.</span>
</li>
<li id="cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017623-4-33"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017623-4_33-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFPapastergiouFairhurstRosBrunstrom2017">Papastergiou et al. 2017</a>, p. 623-4.</span>
</li>
<li id="cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017630-34"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017630_34-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFPapastergiouFairhurstRosBrunstrom2017">Papastergiou et al. 2017</a>, p. 630.</span>
</li>
<li id="cite_note-FOOTNOTECorbet2016-35"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTECorbet2016_35-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFCorbet2016">Corbet 2016</a>.</span>
</li>
<li id="cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017629-36"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017629_36-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFPapastergiouFairhurstRosBrunstrom2017">Papastergiou et al. 2017</a>, p. 629.</span>
</li>
<li id="cite_note-FOOTNOTEThomsonPauly20213.5._Restoring_Active_Use-37"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEThomsonPauly20213.5._Restoring_Active_Use_37-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFThomsonPauly2021">Thomson & Pauly 2021</a>, 3.5. Restoring Active Use.</span>
</li>
<li id="cite_note-FOOTNOTEThomsonPauly2021A.5._TCP-38"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTEThomsonPauly2021A.5._TCP_38-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTEThomsonPauly2021A.5._TCP_38-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFThomsonPauly2021">Thomson & Pauly 2021</a>, A.5. TCP.</span>
</li>
<li id="cite_note-FOOTNOTEEdelineDonnet2019175-176-39"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEEdelineDonnet2019175-176_39-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFEdelineDonnet2019">Edeline & Donnet 2019</a>, p. 175-176.</span>
</li>
<li id="cite_note-FOOTNOTEHesmansDuchenePaaschDetal20131-40"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEHesmansDuchenePaaschDetal20131_40-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFHesmansDuchenePaaschDetal2013">Hesmans et al. 2013</a>, p. 1.</span>
</li>
<li id="cite_note-FOOTNOTERybczyńska2020-41"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTERybczyńska2020_41-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFRybczyńska2020">Rybczyńska 2020</a>.</span>
</li>
<li id="cite_note-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017627-42"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEPapastergiouFairhurstRosBrunstrom2017627_42-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFPapastergiouFairhurstRosBrunstrom2017">Papastergiou et al. 2017</a>, p. 627.</span>
</li>
<li id="cite_note-FOOTNOTEMcQuistinPerkinsFayed20161-43"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEMcQuistinPerkinsFayed20161_43-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFMcQuistinPerkinsFayed2016">McQuistin, Perkins & Fayed 2016</a>, p. 1.</span>
</li>
<li id="cite_note-FOOTNOTESullivan2017-44"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTESullivan2017_44-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFSullivan2017">Sullivan 2017</a>.</span>
</li>
<li id="cite_note-FOOTNOTECorbet2018-45"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTECorbet2018_45-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTECorbet2018_45-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFCorbet2018">Corbet 2018</a>.</span>
</li>
<li id="cite_note-FOOTNOTEThomson20212._Fixed_Properties_of_All_QUIC_Versions-46"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEThomson20212._Fixed_Properties_of_All_QUIC_Versions_46-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFThomson2021">Thomson 2021</a>, 2. Fixed Properties of All QUIC Versions.</span>
</li>
<li id="cite_note-FOOTNOTEKühlewindTrammell20222._The_Necessity_of_Fallback-47"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEKühlewindTrammell20222._The_Necessity_of_Fallback_47-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFKühlewindTrammell2022">Kühlewind & Trammell 2022</a>, 2. The Necessity of Fallback.</span>
</li>
</ol></div></div>
<div class="mw-heading mw-heading2"><h2 id="Bibliography">Bibliography</h2></div>
<ul><li><cite id="CITEREFTrammellKuehlewind2019" class="citation cs1">Trammell, Brian; Kuehlewind, Mirja (April 2019). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc8546"><i>The Wire Image of a Network Protocol</i></a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC8546">10.17487/RFC8546</a></span>. <a href="Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc8546">8546</a>.</cite></li>
<li><cite id="CITEREFHardie2019" class="citation cs1">Hardie, Ted, ed. (April 2019). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc8558"><i>Transport Protocol Path Signals</i></a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC8558">10.17487/RFC8558</a></span>. <a href="Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc8558">8558</a>.</cite></li>
<li><cite id="CITEREFThomson2021" class="citation cs1">Thomson, Martin (May 2021). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc8999"><i>Version-Independent Properties of QUIC</i></a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC8999">10.17487/RFC8999</a></span>. <a href="Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc8999">8999</a>.</cite></li>
<li><cite id="CITEREFFairhurstPerkins2021" class="citation cs1">Fairhurst, Gorry; Perkins, Colin (July 2021). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc9065"><i>Considerations around Transport Header Confidentiality, Network Operations, and the Evolution of Internet Transport Protocols</i></a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC9065">10.17487/RFC9065</a></span>. <a href="Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc9065">9065</a>.</cite></li>
<li><cite id="CITEREFThomsonPauly2021" class="citation cs1">Thomson, Martin; Pauly, Tommy (December 2021). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc9170"><i>Long-Term Viability of Protocol Extension Mechanisms</i></a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC9170">10.17487/RFC9170</a></span>. <a href="Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc9170">9170</a>.</cite></li>
<li><cite id="CITEREFKühlewindTrammell2022" class="citation cs1">Kühlewind, Mirja; Trammell, Brian (September 2022). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc9308"><i>Applicability of the QUIC Transport Protocol</i></a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC9308">10.17487/RFC9308</a></span>. <a href="Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc9308">9308</a>.</cite></li>
<li><cite id="CITEREFArkkoHardiePaulyKühlewind2023" class="citation cs1">Arkko, Jari; Hardie, Ted; Pauly, Tommy; Kühlewind, Mirja (July 2023). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc9419"><i>Considerations on Application - Network Collaboration Using Path Signals</i></a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC9419">10.17487/RFC9419</a></span>. <a href="Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc9419">9419</a>.</cite></li>
<li><cite id="CITEREFHondaNishidaRaiciuGreenhalgh2011" class="citation conference cs1">Honda, Michio; Nishida, Yoshifumi; Raiciu, Costin; Greenhalgh, Adam; <a href="Mark_Handley_(computer_scientist)" title="Mark Handley (computer scientist)">Handley, Mark</a>; Tokuda, Hideyuki (2011). <i>Is It Still Possible to Extend TCP?</i>. 2011 ACM SIGCOMM Conference on Internet Measurement. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F2068816.2068834">10.1145/2068816.2068834</a>.</cite></li>
<li><cite id="CITEREFRaiciuPaaschBarreFord2012" class="citation conference cs1">Raiciu, Costin; Paasch, Christoph; Barre, Sebastien; Ford, Alan; Honda, Michio; Duchene, Fabien; Bonaventure, Olivier; <a href="Mark_Handley_(computer_scientist)" title="Mark Handley (computer scientist)">Handley, Mark</a> (2012). <a rel="nofollow" class="external text" href="https://www.usenix.org/conference/nsdi12/technical-sessions/presentation/raiciu"><i>How Hard Can It Be? Designing and Implementing a Deployable Multipath TCP</i></a>. 9th USENIX Symposium on Networked Systems Design and Implementation (NSDI 12).</cite></li>
<li><cite id="CITEREFHesmansDuchenePaaschDetal2013" class="citation conference cs1">Hesmans, Benjamin; Duchene, Fabien; Paasch, Christoph; Detal, Gregory; Bonaventure, Olivier (2013). <i>Are TCP extensions middlebox-proof?</i>. HotMiddlebox '13. <a href="CiteSeerX_(identifier)" class="mw-redirect" title="CiteSeerX (identifier)">CiteSeerX</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.679.6364">10.1.1.679.6364</a></span>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F2535828.2535830">10.1145/2535828.2535830</a>.</cite></li>
<li><cite id="CITEREFCorbet2015" class="citation web cs1">Corbet, Jonathan (8 December 2015). <a rel="nofollow" class="external text" href="https://lwn.net/Articles/667059/">"Checksum offloads and protocol ossification"</a>. <i><a href="LWN.net" title="LWN.net">LWN.net</a></i>.</cite></li>
<li><cite id="CITEREFCorbet2016" class="citation web cs1">Corbet, Jonathan (20 June 2016). <a rel="nofollow" class="external text" href="https://lwn.net/Articles/691887/">"Transport-level protocols in user space"</a>. <i><a href="LWN.net" title="LWN.net">LWN.net</a></i>.</cite></li>
<li><cite id="CITEREFMcQuistinPerkinsFayed2016" class="citation conference cs1">McQuistin, Stephen; Perkins, Colin; Fayed, Marwan (July 2016). <i>Implementing Real-Time Transport Services over an Ossified Network</i>. 2016 Applied Networking Research Workshop. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F2959424.2959443">10.1145/2959424.2959443</a>. <a href="Hdl_(identifier)" class="mw-redirect" title="Hdl (identifier)">hdl</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://hdl.handle.net/1893%2F26111">1893/26111</a></span>.</cite></li>
<li><cite id="CITEREFPapastergiouFairhurstRosBrunstrom2017" class="citation journal cs1">Papastergiou, Giorgos; Fairhurst, Gorry; Ros, David; Brunstrom, Anna; Grinnemo, Karl-Johan; Hurtig, Per; Khademi, Naeem; Tüxen, Michael; Welzl, Michael; Damjanovic, Dragana; Mangiante, Simone (2017). "De-Ossifying the Internet Transport Layer: A Survey and Future Perspectives". <i><a href="IEEE_Communications_Surveys_%26_Tutorials" class="mw-redirect" title="IEEE Communications Surveys & Tutorials">IEEE Communications Surveys & Tutorials</a></i>. <b>19</b>: <span class="nowrap">619–</span>639. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FCOMST.2016.2626780">10.1109/COMST.2016.2626780</a>. <a href="Hdl_(identifier)" class="mw-redirect" title="Hdl (identifier)">hdl</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://hdl.handle.net/2164%2F8317">2164/8317</a></span>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:1846371">1846371</a>.</cite></li>
<li><cite id="CITEREFSullivan2017" class="citation web cs1">Sullivan, Nick (2017-12-26). <a rel="nofollow" class="external text" href="https://blog.cloudflare.com/why-tls-1-3-isnt-in-browsers-yet/">"Why TLS 1.3 isn't in browsers yet"</a>. <i>The Cloudflare Blog</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2020-03-14</span></span>.</cite></li>
<li><cite id="CITEREFAmmar2018" class="citation journal cs1">Ammar, Mostafa (January 2018). "Ex Uno Pluria: The Service-Infrastructure Cycle, Ossification, and the Fragmentation of the Internet". <i>ACM SIGCOMM Comput. Commun. Rev.</i> <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F3211852.3211861">10.1145/3211852.3211861</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:12169344">12169344</a>.</cite></li>
<li><cite id="CITEREFCorbet2018" class="citation web cs1">Corbet, Jonathan (29 January 2018). <a rel="nofollow" class="external text" href="https://lwn.net/Articles/745590/">"QUIC as a solution to protocol ossification"</a>. <i><a href="LWN.net" title="LWN.net">LWN.net</a></i>.</cite></li>
<li><cite id="CITEREFEdelineDonnet2019" class="citation conference cs1">Edeline, Korian; Donnet, Benoit (2019). <i>A Bottom-Up Investigation of the Transport-Layer Ossification</i>. 2019 Network Traffic Measurement and Analysis Conference (TMA). <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.23919%2FTMA.2019.8784690">10.23919/TMA.2019.8784690</a>.</cite></li>
<li><cite id="CITEREFRybczyńska2020" class="citation web cs1">Rybczyńska, Marta (13 March 2020). <a rel="nofollow" class="external text" href="https://lwn.net/Articles/814522/">"A QUIC look at HTTP/3"</a>. <i><a href="LWN.net" title="LWN.net">LWN.net</a></i>.</cite></li></ul>
<div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2></div>
<ul><li><cite id="CITEREFTrammellKuehlewind2015" class="citation cs1">Trammell, Brian; Kuehlewind, Mirja, eds. (October 2015). <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc7663"><i>Report from the IAB Workshop on Stack Evolution in a Middlebox Internet (SEMI)</i></a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.17487%2FRFC7663">10.17487/RFC7663</a></span>. <a href="Request_for_Comments" title="Request for Comments">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc7663">7663</a>.</cite></li></ul></div><!--htdig_noindex--><div><div class="zim-footer">
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