8. Undocumented TCP Features There are a few important implementation tactics for the TCP that have not yet been described in any RFC. Although this roadmap is primarily concerned with mapping the TCP RFCs, this section is included because an implementer needs to be aware of these important issues. Header Prediction Header prediction is a trick to speed up the processing of segments. Van Jacobson and Mike Karels developed the technique in the late 1980s. The basic idea is that some processing time can be saved when most of a segment's fields can be predicted from previous segments. A good description of this was sent to the TCP-IP mailing list by Van Jacobson on March 9, 1988 (see [Jacobson] for the full message): 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] includes an alternate algorithm for triggering fast retransmit [RFC5681], based on the extent of the SACK scoreboard. Its goal is to trigger fast retransmit as soon as the receiver's reassembly queue is larger than the duplicate ACK threshold, as indicated by the difference between the forward most SACK block edge and SND.UNA. This algorithm quickly and reliably triggers fast retransmit in the presence of burst losses -- often on the first SACK following such a loss. Such a threshold-based algorithm also triggers fast retransmit immediately in the presence of any reordering with extent greater than the duplicate ACK threshold. FACK is implemented in Linux and turned on per default. Congestion Control for High Rate Flows In the last decade significant research effort has been put into experimental TCP congestion control modifications for obtaining high throughput with reduced startup and recovery times. Only a few RFCs have been published on some of these modifications, including HighSpeed TCP [RFC3649], Limited Slow-Start [RFC3742], and Quick-Start [RFC4782] (see Section 4.3 of this document for more information on each), but high-rate congestion control mechanisms are still considered an open issue in congestion control research. Some other schemes have been published as Internet-Drafts, e.g. CUBIC [CUBIC] (the standard TCP congestion control algorithm in Linux), Compound TCP [CTCP], and H-TCP [HTCP] or have been discussed a little by the IETF, but much of the work in this area has not been adopted within the IETF yet, so the majority of this work is outside the RFC series and 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.
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>. [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>. [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>. 10.2. Informative References [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 This document grew out of a discussion on the end2end-interest mailing list, the public list of the End-to-End Research Group of the IRTF, and continued development under the IETF's TCP Maintenance and Minor Extensions (TCPM) working group. We thank 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 provided some useful notes and clarification on the various MIB-related RFCs.
Authors' Addresses Martin Duke F5 Networks 401 Elliott Ave W Seattle, WA 98119 United States Phone: 206-272-7537 EMail: firstname.lastname@example.org Robert Braden USC Information Sciences Institute Marina del Rey, CA 90292-6695 United States Phone: 310-448-9173 EMail: email@example.com Wesley M. Eddy MTI Systems 18013 Cleveland Parkway Suite 170 Cleveland, OH 44135 United States Phone: 216-433-6682 EMail: firstname.lastname@example.org Ethan Blanton Interrupt Sciences EMail: email@example.com Alexander Zimmermann NetApp, Inc. Sonnenallee 1 Kirchheim 85551 Germany Phone: +49 89 900594712 EMail: firstname.lastname@example.org