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RFC 8095


Services Provided by IETF Transport Protocols and Congestion Control Mechanisms

Part 3 of 3, p. 38 to 54
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prevText      Top      ToC       Page 38 
4.  Congestion Control

   Congestion control is critical to the stable operation of the
   Internet.  A variety of mechanisms are used to provide the congestion
   control needed by many Internet transport protocols.  Congestion is
   detected based on sensing of network conditions, whether through
   explicit or implicit feedback.  The congestion control mechanisms
   that can be applied by different transport protocols are largely
   orthogonal to the choice of transport protocol.  This section
   provides an overview of the congestion control mechanisms available
   to the protocols described in Section 3.

   Many protocols use a separate window to determine the maximum sending
   rate that is allowed by the congestion control.  The used congestion
   control mechanism will increase the congestion window if feedback is
   received that indicates that the currently used network path is not
   congested and will reduce the window otherwise.  Window-based
   mechanisms often increase their window slowing over multiple RTTs,
   while decreasing strongly when the first indication of congestion is
   received.  One example is an Additive Increase Multiplicative
   Decrease (AIMD) scheme, where the window is increased by a certain
   number of packets/bytes for each data segment that has been
   successfully transmitted, while the window decreases multiplicatively
   on the occurrence of a congestion event.  This can lead to a rather
   unstable, oscillating sending rate but will resolve a congestion
   situation quickly.  Examples of window-based AIMD schemes include TCP
   NewReno [RFC5681], TCP Cubic [CUBIC] (the default mechanism for TCP
   in Linux), and CCID 2 specified for DCCP [RFC4341].

   Some classes of applications prefer to use a transport service that
   allows sending at a more stable rate that is slowly varied in
   response to congestion.  Rate-based methods offer this type of
   congestion control and have been defined based on the loss ratio and
   observed round-trip time, such as TFRC [RFC5348] and TFRC-SP

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   [RFC4828].  These methods utilize a throughput equation to determine
   the maximum acceptable rate.  Such methods are used with DCCP CCID 3
   [RFC4342], CCID 4 [RFC5622], WEBRC [RFC3738], and other applications.

   Another class of applications prefers a transport service that yields
   to other (higher-priority) traffic, such as interactive
   transmissions.  While most traffic in the Internet uses loss-based
   congestion control and therefore tends to fill the network buffers
   (to a certain level if Active Queue Management (AQM) is used), low-
   priority congestion control methods often react to changes in delay
   as an earlier indication of congestion.  This approach tends to
   induce less loss than a loss-based method but does generally not
   compete well with loss-based traffic across shared bottleneck links.
   Therefore, methods such as LEDBAT [RFC6817] are deployed in the
   Internet for scavenger traffic that aims to only utilize otherwise
   unused capacity.

5.  Transport Features

   The transport protocol features described in this document can be
   used as a basis for defining common transport features.  These are
   listed below with the protocols supporting them:

   o  Control Functions

      *  Addressing

         +  unicast (TCP, MPTCP, UDP, UDP-Lite, SCTP, DCCP, TLS, RTP,
            HTTP, ICMP)

         +  multicast (UDP, UDP-Lite, RTP, ICMP, FLUTE/ALC, NORM).  Note
            that, as TLS and DTLS are unicast-only, there is no widely
            deployed mechanism for supporting the features listed under
            the Security bullet (below) when using multicast addressing.

         +  IPv4 broadcast (UDP, UDP-Lite, ICMP)

         +  anycast (UDP, UDP-Lite).  Connection-oriented protocols such
            as TCP and DCCP have also been deployed using anycast
            addressing, with the risk that routing changes may cause
            connection failure.

      *  Association type

         +  connection-oriented (TCP, MPTCP, DCCP, SCTP, TLS, RTP, HTTP,

         +  connectionless (UDP, UDP-Lite, FLUTE/ALC)

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      *  Multihoming support

         +  resilience and mobility (MPTCP, SCTP)

         +  load balancing (MPTCP)

         +  address family multiplexing (MPTCP, SCTP)

      *  Middlebox cooperation

         +  application-class signaling to middleboxes (DCCP)

         +  error condition signaling from middleboxes and routers to
            endpoints (ICMP)

      *  Signaling

         +  control information and error signaling (ICMP)

         +  application performance reporting (RTP)

   o  Delivery

      *  Reliability

         +  fully reliable delivery (TCP, MPTCP, SCTP, TLS, HTTP, FLUTE/
            ALC, NORM)

         +  partially reliable delivery (SCTP, NORM)

            -  using packet erasure coding (RTP, FLUTE/ALC, NORM)

            -  with specified policy for dropped messages (SCTP)

         +  unreliable delivery (SCTP, UDP, UDP-Lite, DCCP, RTP)

            -  with drop notification to sender (SCTP, DCCP, RTP)

         +  error detection

            -  checksum for error detection (TCP, MPTCP, UDP, UDP-Lite,

            -  partial payload checksum protection (UDP-Lite, DCCP).
               Some uses of RTP can exploit partial payload checksum
               protection feature to provide a corruption-tolerant
               transport service.

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            -  checksum optional (UDP).  Possible with IPv4 and, in
               certain cases, with IPv6.

      *  Ordering

         +  ordered delivery (TCP, MPTCP, SCTP, TLS, RTP, HTTP, FLUTE)

         +  unordered delivery permitted (UDP, UDP-Lite, SCTP, DCCP,
            RTP, NORM)

      *  Type/framing

         +  stream-oriented delivery (TCP, MPTCP, SCTP, TLS, HTTP)

            -  with multiple streams per association (SCTP, HTTP2)

         +  message-oriented delivery (UDP, UDP-Lite, SCTP, DCCP, DTLS,

         +  object-oriented delivery of discrete data or files and
            associated metadata (HTTP, FLUTE/ALC, NORM)

            -  with partial delivery of object ranges (HTTP)

      *  Directionality

         +  unidirectional (UDP, UDP-Lite, DCCP, RTP, FLUTE/ALC, NORM)

         +  bidirectional (TCP, MPTCP, SCTP, TLS, HTTP)

   o  Transmission control

      *  flow control (TCP, MPTCP, SCTP, DCCP, TLS, RTP, HTTP)

      *  congestion control (TCP, MPTCP, SCTP, DCCP, RTP, FLUTE/ALC,
         NORM).  Congestion control can also provided by the transport
         supporting an upper-layer transport (e.g., TLS, RTP, HTTP).

      *  segmentation (TCP, MPTCP, SCTP, TLS, RTP, HTTP, FLUTE/ALC,

      *  data/message bundling (TCP, MPTCP, SCTP, TLS, HTTP)

      *  stream scheduling prioritization (SCTP, HTTP2)

      *  endpoint multiplexing (MPTCP)

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   o  Security

      *  authentication of one end of a connection (TLS, DTLS, FLUTE/

      *  authentication of both ends of a connection (TLS, DTLS)

      *  confidentiality (TLS, DTLS)

      *  cryptographic integrity protection (TLS, DTLS)

      *  replay protection (TLS, DTLS, FLUTE/ALC)

6.  IANA Considerations

   This document does not require any IANA actions.

7.  Security Considerations

   This document surveys existing transport protocols and protocols
   providing transport-like services.  Confidentiality, integrity, and
   authenticity are among the features provided by those services.  This
   document does not specify any new features or mechanisms for
   providing these features.  Each RFC referenced by this document
   discusses the security considerations of the specification it

8.  Informative References

              Clark, D. and D. Tennenhouse, "Architectural
              Considerations for a New Generation of Protocols",
              Proceedings of ACM SIGCOMM, DOI 10.1145/99517.99553, 1990.

   [CUBIC]    Rhee, I., Xu, L., Ha, S., Zimmermann, A., Eggert, L., and
              R. Scheffenegger, "CUBIC for Fast Long-Distance Networks",
              Work in Progress, draft-ietf-tcpm-cubic-04, February 2017.

   [MBMS]     3GPP, "Multimedia Broadcast/Multicast Service (MBMS);
              Protocols and codecs", 3GPP TS 26.346, 2015,

   [NAT-SUPP] Stewart, R., Tuexen, M., and I. Ruengeler, "Stream Control
              Transmission Protocol (SCTP) Network Address Translation
              Support", Work in Progress, draft-ietf-tsvwg-natsupp-09,
              May 2016.

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   [POSIX]    IEEE, "Standard for Information Technology -- Portable
              Operating System Interface (POSIX(R)) Base Specifications,
              Issue 7", IEEE 1003.1, DOI 10.1109/ieeestd.2016.7582338,

   [REST]     Fielding, R., "Architectural Styles and the Design of
              Network-based Software Architectures, Chapter 5:
              Representational State Transfer", Ph.D.
              Dissertation, University of California, Irvine, 2000.

   [RFC768]   Postel, J., "User Datagram Protocol", STD 6, RFC 768,
              DOI 10.17487/RFC0768, August 1980,

   [RFC792]   Postel, J., "Internet Control Message Protocol", STD 5,
              RFC 792, DOI 10.17487/RFC0792, September 1981,

   [RFC793]   Postel, J., "Transmission Control Protocol", STD 7,
              RFC 793, DOI 10.17487/RFC0793, September 1981,

   [RFC1071]  Braden, R., Borman, D., and C. Partridge, "Computing the
              Internet checksum", RFC 1071, DOI 10.17487/RFC1071,
              September 1988, <>.

   [RFC1122]  Braden, R., Ed., "Requirements for Internet Hosts -
              Communication Layers", STD 3, RFC 1122,
              DOI 10.17487/RFC1122, October 1989,

   [RFC1191]  Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
              DOI 10.17487/RFC1191, November 1990,

   [RFC1812]  Baker, F., Ed., "Requirements for IP Version 4 Routers",
              RFC 1812, DOI 10.17487/RFC1812, June 1995,

   [RFC1981]  McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery
              for IP version 6", RFC 1981, DOI 10.17487/RFC1981, August
              1996, <>.

   [RFC2018]  Mathis, M., Mahdavi, J., Floyd, S., and A. Romanow, "TCP
              Selective Acknowledgment Options", RFC 2018,
              DOI 10.17487/RFC2018, October 1996,

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   [RFC2045]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part One: Format of Internet Message
              Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996,

   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
              December 1998, <>.

   [RFC2710]  Deering, S., Fenner, W., and B. Haberman, "Multicast
              Listener Discovery (MLD) for IPv6", RFC 2710,
              DOI 10.17487/RFC2710, October 1999,

   [RFC2736]  Handley, M. and C. Perkins, "Guidelines for Writers of RTP
              Payload Format Specifications", BCP 36, RFC 2736,
              DOI 10.17487/RFC2736, December 1999,

   [RFC3168]  Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
              of Explicit Congestion Notification (ECN) to IP",
              RFC 3168, DOI 10.17487/RFC3168, September 2001,

   [RFC3205]  Moore, K., "On the use of HTTP as a Substrate", BCP 56,
              RFC 3205, DOI 10.17487/RFC3205, February 2002,

   [RFC3260]  Grossman, D., "New Terminology and Clarifications for
              Diffserv", RFC 3260, DOI 10.17487/RFC3260, April 2002,

   [RFC3436]  Jungmaier, A., Rescorla, E., and M. Tuexen, "Transport
              Layer Security over Stream Control Transmission Protocol",
              RFC 3436, DOI 10.17487/RFC3436, December 2002,

   [RFC3450]  Luby, M., Gemmell, J., Vicisano, L., Rizzo, L., and J.
              Crowcroft, "Asynchronous Layered Coding (ALC) Protocol
              Instantiation", RFC 3450, DOI 10.17487/RFC3450, December
              2002, <>.

   [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.
              Jacobson, "RTP: A Transport Protocol for Real-Time
              Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
              July 2003, <>.

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   [RFC3738]  Luby, M. and V. Goyal, "Wave and Equation Based Rate
              Control (WEBRC) Building Block", RFC 3738,
              DOI 10.17487/RFC3738, April 2004,

   [RFC3758]  Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P.
              Conrad, "Stream Control Transmission Protocol (SCTP)
              Partial Reliability Extension", RFC 3758,
              DOI 10.17487/RFC3758, May 2004,

   [RFC3828]  Larzon, L-A., Degermark, M., Pink, S., Jonsson, L-E., Ed.,
              and G. Fairhurst, Ed., "The Lightweight User Datagram
              Protocol (UDP-Lite)", RFC 3828, DOI 10.17487/RFC3828, July
              2004, <>.

   [RFC3926]  Paila, T., Luby, M., Lehtonen, R., Roca, V., and R. Walsh,
              "FLUTE - File Delivery over Unidirectional Transport",
              RFC 3926, DOI 10.17487/RFC3926, October 2004,

   [RFC3971]  Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
              "SEcure Neighbor Discovery (SEND)", RFC 3971,
              DOI 10.17487/RFC3971, March 2005,

   [RFC4336]  Floyd, S., Handley, M., and E. Kohler, "Problem Statement
              for the Datagram Congestion Control Protocol (DCCP)",
              RFC 4336, DOI 10.17487/RFC4336, March 2006,

   [RFC4340]  Kohler, E., Handley, M., and S. Floyd, "Datagram
              Congestion Control Protocol (DCCP)", RFC 4340,
              DOI 10.17487/RFC4340, March 2006,

   [RFC4341]  Floyd, S. and E. Kohler, "Profile for Datagram Congestion
              Control Protocol (DCCP) Congestion Control ID 2: TCP-like
              Congestion Control", RFC 4341, DOI 10.17487/RFC4341, March
              2006, <>.

   [RFC4342]  Floyd, S., Kohler, E., and J. Padhye, "Profile for
              Datagram Congestion Control Protocol (DCCP) Congestion
              Control ID 3: TCP-Friendly Rate Control (TFRC)", RFC 4342,
              DOI 10.17487/RFC4342, March 2006,

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   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet
              Control Message Protocol (ICMPv6) for the Internet
              Protocol Version 6 (IPv6) Specification", RFC 4443,
              DOI 10.17487/RFC4443, March 2006,

   [RFC4654]  Widmer, J. and M. Handley, "TCP-Friendly Multicast
              Congestion Control (TFMCC): Protocol Specification",
              RFC 4654, DOI 10.17487/RFC4654, August 2006,

   [RFC4820]  Tuexen, M., Stewart, R., and P. Lei, "Padding Chunk and
              Parameter for the Stream Control Transmission Protocol
              (SCTP)", RFC 4820, DOI 10.17487/RFC4820, March 2007,

   [RFC4821]  Mathis, M. and J. Heffner, "Packetization Layer Path MTU
              Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007,

   [RFC4828]  Floyd, S. and E. Kohler, "TCP Friendly Rate Control
              (TFRC): The Small-Packet (SP) Variant", RFC 4828,
              DOI 10.17487/RFC4828, April 2007,

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              DOI 10.17487/RFC4861, September 2007,

   [RFC4895]  Tuexen, M., Stewart, R., Lei, P., and E. Rescorla,
              "Authenticated Chunks for the Stream Control Transmission
              Protocol (SCTP)", RFC 4895, DOI 10.17487/RFC4895, August
              2007, <>.

   [RFC4960]  Stewart, R., Ed., "Stream Control Transmission Protocol",
              RFC 4960, DOI 10.17487/RFC4960, September 2007,

   [RFC5052]  Watson, M., Luby, M., and L. Vicisano, "Forward Error
              Correction (FEC) Building Block", RFC 5052,
              DOI 10.17487/RFC5052, August 2007,

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   [RFC5061]  Stewart, R., Xie, Q., Tuexen, M., Maruyama, S., and M.
              Kozuka, "Stream Control Transmission Protocol (SCTP)
              Dynamic Address Reconfiguration", RFC 5061,
              DOI 10.17487/RFC5061, September 2007,

   [RFC5097]  Renker, G. and G. Fairhurst, "MIB for the UDP-Lite
              protocol", RFC 5097, DOI 10.17487/RFC5097, January 2008,

   [RFC5238]  Phelan, T., "Datagram Transport Layer Security (DTLS) over
              the Datagram Congestion Control Protocol (DCCP)",
              RFC 5238, DOI 10.17487/RFC5238, May 2008,

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,

   [RFC5348]  Floyd, S., Handley, M., Padhye, J., and J. Widmer, "TCP
              Friendly Rate Control (TFRC): Protocol Specification",
              RFC 5348, DOI 10.17487/RFC5348, September 2008,

   [RFC5461]  Gont, F., "TCP's Reaction to Soft Errors", RFC 5461,
              DOI 10.17487/RFC5461, February 2009,

   [RFC5595]  Fairhurst, G., "The Datagram Congestion Control Protocol
              (DCCP) Service Codes", RFC 5595, DOI 10.17487/RFC5595,
              September 2009, <>.

   [RFC5596]  Fairhurst, G., "Datagram Congestion Control Protocol
              (DCCP) Simultaneous-Open Technique to Facilitate NAT/
              Middlebox Traversal", RFC 5596, DOI 10.17487/RFC5596,
              September 2009, <>.

   [RFC5622]  Floyd, S. and E. Kohler, "Profile for Datagram Congestion
              Control Protocol (DCCP) Congestion ID 4: TCP-Friendly Rate
              Control for Small Packets (TFRC-SP)", RFC 5622,
              DOI 10.17487/RFC5622, August 2009,

   [RFC5651]  Luby, M., Watson, M., and L. Vicisano, "Layered Coding
              Transport (LCT) Building Block", RFC 5651,
              DOI 10.17487/RFC5651, October 2009,

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   [RFC5681]  Allman, M., Paxson, V., and E. Blanton, "TCP Congestion
              Control", RFC 5681, DOI 10.17487/RFC5681, September 2009,

   [RFC5740]  Adamson, B., Bormann, C., Handley, M., and J. Macker,
              "NACK-Oriented Reliable Multicast (NORM) Transport
              Protocol", RFC 5740, DOI 10.17487/RFC5740, November 2009,

   [RFC5762]  Perkins, C., "RTP and the Datagram Congestion Control
              Protocol (DCCP)", RFC 5762, DOI 10.17487/RFC5762, April
              2010, <>.

   [RFC5775]  Luby, M., Watson, M., and L. Vicisano, "Asynchronous
              Layered Coding (ALC) Protocol Instantiation", RFC 5775,
              DOI 10.17487/RFC5775, April 2010,

   [RFC6056]  Larsen, M. and F. Gont, "Recommendations for Transport-
              Protocol Port Randomization", BCP 156, RFC 6056,
              DOI 10.17487/RFC6056, January 2011,

   [RFC6083]  Tuexen, M., Seggelmann, R., and E. Rescorla, "Datagram
              Transport Layer Security (DTLS) for Stream Control
              Transmission Protocol (SCTP)", RFC 6083,
              DOI 10.17487/RFC6083, January 2011,

   [RFC6093]  Gont, F. and A. Yourtchenko, "On the Implementation of the
              TCP Urgent Mechanism", RFC 6093, DOI 10.17487/RFC6093,
              January 2011, <>.

   [RFC6101]  Freier, A., Karlton, P., and P. Kocher, "The Secure
              Sockets Layer (SSL) Protocol Version 3.0", RFC 6101,
              DOI 10.17487/RFC6101, August 2011,

   [RFC6347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
              January 2012, <>.

   [RFC6356]  Raiciu, C., Handley, M., and D. Wischik, "Coupled
              Congestion Control for Multipath Transport Protocols",
              RFC 6356, DOI 10.17487/RFC6356, October 2011,

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   [RFC6363]  Watson, M., Begen, A., and V. Roca, "Forward Error
              Correction (FEC) Framework", RFC 6363,
              DOI 10.17487/RFC6363, October 2011,

   [RFC6458]  Stewart, R., Tuexen, M., Poon, K., Lei, P., and V.
              Yasevich, "Sockets API Extensions for the Stream Control
              Transmission Protocol (SCTP)", RFC 6458,
              DOI 10.17487/RFC6458, December 2011,

   [RFC6525]  Stewart, R., Tuexen, M., and P. Lei, "Stream Control
              Transmission Protocol (SCTP) Stream Reconfiguration",
              RFC 6525, DOI 10.17487/RFC6525, February 2012,

   [RFC6582]  Henderson, T., Floyd, S., Gurtov, A., and Y. Nishida, "The
              NewReno Modification to TCP's Fast Recovery Algorithm",
              RFC 6582, DOI 10.17487/RFC6582, April 2012,

   [RFC6584]  Roca, V., "Simple Authentication Schemes for the
              Asynchronous Layered Coding (ALC) and NACK-Oriented
              Reliable Multicast (NORM) Protocols", RFC 6584,
              DOI 10.17487/RFC6584, April 2012,

   [RFC6726]  Paila, T., Walsh, R., Luby, M., Roca, V., and R. Lehtonen,
              "FLUTE - File Delivery over Unidirectional Transport",
              RFC 6726, DOI 10.17487/RFC6726, November 2012,

   [RFC6773]  Phelan, T., Fairhurst, G., and C. Perkins, "DCCP-UDP: A
              Datagram Congestion Control Protocol UDP Encapsulation for
              NAT Traversal", RFC 6773, DOI 10.17487/RFC6773, November
              2012, <>.

   [RFC6817]  Shalunov, S., Hazel, G., Iyengar, J., and M. Kuehlewind,
              "Low Extra Delay Background Transport (LEDBAT)", RFC 6817,
              DOI 10.17487/RFC6817, December 2012,

   [RFC6824]  Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,
              "TCP Extensions for Multipath Operation with Multiple
              Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013,

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   [RFC6897]  Scharf, M. and A. Ford, "Multipath TCP (MPTCP) Application
              Interface Considerations", RFC 6897, DOI 10.17487/RFC6897,
              March 2013, <>.

   [RFC6935]  Eubanks, M., Chimento, P., and M. Westerlund, "IPv6 and
              UDP Checksums for Tunneled Packets", RFC 6935,
              DOI 10.17487/RFC6935, April 2013,

   [RFC6936]  Fairhurst, G. and M. Westerlund, "Applicability Statement
              for the Use of IPv6 UDP Datagrams with Zero Checksums",
              RFC 6936, DOI 10.17487/RFC6936, April 2013,

   [RFC6951]  Tuexen, M. and R. Stewart, "UDP Encapsulation of Stream
              Control Transmission Protocol (SCTP) Packets for End-Host
              to End-Host Communication", RFC 6951,
              DOI 10.17487/RFC6951, May 2013,

   [RFC7053]  Tuexen, M., Ruengeler, I., and R. Stewart, "SACK-
              IMMEDIATELY Extension for the Stream Control Transmission
              Protocol", RFC 7053, DOI 10.17487/RFC7053, November 2013,

   [RFC7202]  Perkins, C. and M. Westerlund, "Securing the RTP
              Framework: Why RTP Does Not Mandate a Single Media
              Security Solution", RFC 7202, DOI 10.17487/RFC7202, April
              2014, <>.

   [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Message Syntax and Routing",
              RFC 7230, DOI 10.17487/RFC7230, June 2014,

   [RFC7231]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
              DOI 10.17487/RFC7231, June 2014,

   [RFC7232]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Conditional Requests", RFC 7232,
              DOI 10.17487/RFC7232, June 2014,

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   [RFC7233]  Fielding, R., Ed., Lafon, Y., Ed., and J. Reschke, Ed.,
              "Hypertext Transfer Protocol (HTTP/1.1): Range Requests",
              RFC 7233, DOI 10.17487/RFC7233, June 2014,

   [RFC7234]  Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
              Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
              RFC 7234, DOI 10.17487/RFC7234, June 2014,

   [RFC7235]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Authentication", RFC 7235,
              DOI 10.17487/RFC7235, June 2014,

   [RFC7301]  Friedl, S., Popov, A., Langley, A., and E. Stephan,
              "Transport Layer Security (TLS) Application-Layer Protocol
              Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
              July 2014, <>.

   [RFC7323]  Borman, D., Braden, B., Jacobson, V., and R.
              Scheffenegger, Ed., "TCP Extensions for High Performance",
              RFC 7323, DOI 10.17487/RFC7323, September 2014,

   [RFC7414]  Duke, M., Braden, R., Eddy, W., Blanton, E., and A.
              Zimmermann, "A Roadmap for Transmission Control Protocol
              (TCP) Specification Documents", RFC 7414,
              DOI 10.17487/RFC7414, February 2015,

   [RFC7457]  Sheffer, Y., Holz, R., and P. Saint-Andre, "Summarizing
              Known Attacks on Transport Layer Security (TLS) and
              Datagram TLS (DTLS)", RFC 7457, DOI 10.17487/RFC7457,
              February 2015, <>.

   [RFC7496]  Tuexen, M., Seggelmann, R., Stewart, R., and S. Loreto,
              "Additional Policies for the Partially Reliable Stream
              Control Transmission Protocol Extension", RFC 7496,
              DOI 10.17487/RFC7496, April 2015,

   [RFC7525]  Sheffer, Y., Holz, R., and P. Saint-Andre,
              "Recommendations for Secure Use of Transport Layer
              Security (TLS) and Datagram Transport Layer Security
              (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
              2015, <>.

Top      Up      ToC       Page 52 
   [RFC7540]  Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
              Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
              DOI 10.17487/RFC7540, May 2015,

   [RFC8085]  Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
              Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
              March 2017, <>.

              Tuexen, M., Stewart, R., Jesup, R., and S. Loreto, "DTLS
              Encapsulation of SCTP Packets", Work in Progress,
              draft-ietf-tsvwg-sctp-dtls-encaps-09, January 2015.

              Stewart, R., Tuexen, M., Loreto, S., and R. Seggelmann,
              "Stream Schedulers and User Message Interleaving for the
              Stream Control Transmission Protocol", Work in Progress,
              draft-ietf-tsvwg-sctp-ndata-08, October 2016.

   [TCP-SPEC] Eddy, W., Ed., "Transmission Control Protocol
              Specification", Work in Progress, draft-ietf-tcpm-
              rfc793bis-04, December 2016.

   [TLS-1.3]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", Work in Progress, draft-ietf-tls-tls13-18,
              October 2016.

              Alvestrand, H., "Transports for WebRTC", Work in
              Progress, draft-ietf-rtcweb-transports-17, October 2016.

   [XHR]      van Kesteren, A., Aubourg, J., Song, J., and H. Steen,
              "XMLHttpRequest Level 1", World Wide Web Consortium NOTE-
              XMLHttpRequest-20161006, October 2016,

Top      Up      ToC       Page 53 

   Thanks to Joe Touch, Michael Welzl, Spencer Dawkins, and the TAPS
   working group for the comments, feedback, and discussion.  This work
   is supported by the European Commission under grant agreement No.
   318627 mPlane and from the Horizon 2020 research and innovation
   program under grant agreements No. 644334 (NEAT) and No. 688421
   (MAMI).  This support does not imply endorsement.


   In addition to the editors, this document is the work of Brian
   Adamson, Dragana Damjanovic, Kevin Fall, Simone Ferlin-Oliviera,
   Ralph Holz, Olivier Mehani, Karen Nielsen, Colin Perkins, Vincent
   Roca, and Michael Tuexen.

   o  Section 3.2 on MPTCP was contributed by Simone Ferlin-Oliviera
      ( and Olivier Mehani

   o  Section 3.3 on UDP was contributed by Kevin Fall

   o  Section 3.5 on SCTP was contributed by Michael Tuexen (tuexen@fh- and Karen Nielsen (

   o  Section 3.7 on TLS and DTLS was contributed by Ralph Holz
      ( and Olivier Mehani

   o  Section 3.8 on RTP contains contributions from Colin Perkins

   o  Section 3.9 on HTTP was contributed by Dragana Damjanovic

   o  Section 3.10 on FLUTE/ALC was contributed by Vincent Roca

   o  Section 3.11 on NORM was contributed by Brian Adamson

Top      Up      ToC       Page 54 
Authors' Addresses

   Godred Fairhurst (editor)
   University of Aberdeen
   School of Engineering, Fraser Noble Building
   Aberdeen AB24 3UE


   Brian Trammell (editor)
   ETH Zurich
   Gloriastrasse 35
   8092 Zurich


   Mirja Kuehlewind (editor)
   ETH Zurich
   Gloriastrasse 35
   8092 Zurich