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TCP Maintenance and Minor Extensions (tcpm)

WG Name TCP Maintenance and Minor Extensions
Acronym tcpm
Area Transport Area (tsv)
State Active
Charter charter-ietf-tcpm-09-01 Start Chartering/Rechartering (Internal Steering Group/IAB Review)
Status update Show Changed 2020-07-23
Document dependencies
Additional resources Issue tracker, Wiki, Zulip Stream
Personnel Chairs Ian Swett, Michael Tüxen, Yoshifumi Nishida
Area Director Martin Duke
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Charter for Working Group

TCP is currently the Internet's predominant transport protocol. TCPM
is the working group within the IETF that handles small TCP changes,
i.e., minor extensions to TCP algorithms and protocol mechanisms.
The TCPM WG serves several purposes:

  • The WG mostly focuses on maintenance issues (e.g., bug fixes) and
    modest changes to the protocol, algorithms, and interfaces that
    maintain TCP's utility.

  • The WG is a venue for moving current TCP specifications along the
    standards track (as community energy is available for such efforts).

  • The WG maintains Multipath TCP (MPTCP) and is a home for minor
    MPTCP enhancements including updates to the existing multipath
    congestion control.

  • The focus of the working group is TCP. In cases where small
    changes are directly applicable to other transports (e.g., SCTP or
    DCCP), the mappings to other transports may be specified alongside
    that for TCP, but other significant additions and changes to other
    transports are not in scope.

TCPM also provides a venue for standardization of incremental
enhancements of TCP's standard congestion control. In addition,
TCPM may document alternative TCP congestion control algorithms
that are known to be widely deployed, and that are considered
safe for large-scale deployment in the Internet. Changes of algorithms
may require additional review by the IRTF Congestion Control
Research Group (ICCRG). Fundamental changes to TCP or its congestion
control algorithms (e.g., departure from loss-based congestion
control) will be handled by other working groups or will require

TCP's congestion control algorithms are the model followed by
other IETF transports (e.g., SCTP or DCCP), which are standardized in
other working groups, such as the Transport Area WG (tsvwg). In the
past, the IETF has worked on several documents about algorithms that
are specified for multiple protocols (e.g., TCP and SCTP) in the
same document. Which WG shepherds such documents will be determined
on a case-by-case basis. In any case, the TCPM WG will remain in
close contact with other relevant WGs working on these protocols to
ensure openness and stringent review from all angles.

New TCPM milestones that fall within the scope specified within the
charter can be added after consensus on acceptance in the working
group and approval by the responsible Area Director.


Date Milestone Associated documents
Oct 2024 Submit document on adding acknowledgement rate handling for TCP to the IESG for publication as Experimental RFC draft-ietf-tcpm-ack-rate-request
Dec 2023 Submit document on a TCP Extended Data Offset Option to the IESG as a Proposed Standard RFC draft-ietf-tcpm-tcp-edo
Jan 2023 Submit document on adding Explicit Congestion Notification (ECN) to TCP Control Packets to the IESG for publication as Experimental RFC draft-ietf-tcpm-generalized-ecn
Dec 2022 Submit specification of more accurate ECN feedback in TCP to the IESG for publication as a Proposed Standard RFC draft-ietf-tcpm-accurate-ecn
Nov 2022 Submit RFC6937bis document to the IESG for publication as a Proposed Standard RFC draft-ietf-tcpm-prr-rfc6937bis

Done milestones

Date Milestone Associated documents
Done Submit a document on modifying slow start to avoid large tail drops as a Proposed Standard RFC draft-ietf-tcpm-hystartplusplus
Done Submit RFC8312bis document to the IESG for publication as a Proposed Standard RFC draft-ietf-tcpm-rfc8312bis
Done Submit documents on TCP-AO Test Vectors as an Informational RFC draft-ietf-tcpm-ao-test-vectors
Done Submit document on YANG model for TCP configuration as a Proposed Standard RFC draft-ietf-tcpm-yang-tcp
Done Submit document on TCP Control Block Interdependence to the IESG for publication as Informational RFC draft-ietf-tcpm-2140bis
Done Submit RFC793bis document to the IESG for publication as Internet Standard draft-ietf-tcpm-rfc793bis
Done Submit document on Retransmission Timeout Considerations as Best Current Practice RFC draft-ietf-tcpm-rto-consider
Done Submit document on a time-based fast loss detection algorithm for TCP to the IESG for publication as a Proposed Standard RFC draft-ietf-tcpm-rack