RFC 5033 describes a Best Current Practice to evaluate new congestion control algorithms as Experimental or Proposed Standard RFCs. TCP was the dominant consumer of this work, and proposals were typically discussed in research groups, for example the Internet Congestion Control Research Group (ICCRG).

Since RFC 5033 was published, many conditions have changed. Congestion control algorithm proponents now often have the opportunity to test and deploy at scale without IETF review. The set of protocols using these algorithms has spread beyond TCP and SCTP to include DCCP, QUIC, and beyond. There is more interest in specialized use cases such as data centers and real-time protocols. Finally, the community has gained much more experience with indications of congestion beyond packet loss.

The Congestion Control Working Group will analyze some of the impediments to congestion control work occurring in the IETF and can generalize transports from TCP to all of the relevant transport protocols. This will inform a revision of RFC 5033 (5033bis) that encourages IETF review of congestion control proposals and standardization of mature congestion control algorithms. 

The congestion control expertise in the working group also makes it a natural venue to take on other work related to indications of congestion such as delay, queuing algorithms, rate pacing, multipath, interaction with other layers, among others. In particular, it can address congestion control algorithms with empirical evidence of safety (for example - avoiding congestion collapse) and stated intent to deploy by major implementations. The working group is intended to be a home for such work, and it is chartered to adopt proposals in this space if such congestion control algorithms are presented before or after the completion of the primary deliverable i.e. 5033bis.

The group will coordinate closely with other relevant working and research groups, including ICCRG, TCPM, QUIC, and TSVWG. Documents in CCWG will remain as transport protocol agnostic as possible, but they may have short specific instructions, such as header options or parameter formats, for one or more protocols. Documents that are wholly specific to mechanisms in a single protocol will remain in the maintenance working group for that protocol. Algorithms proposed for Experimental status, in consultation with ICCRG, based on an assessment of their maturity and likelihood of near-term wide-scale deployment, are in scope.

Publication of Informational RFCs analyzing the published standard congestion control algorithms is within CCWG scope. However, it is not chartered to document the state of congestion control in the Internet, including assessments of whether any particular implementation complies with existing standards. Other venues, such as the IRTF, may be more appropriate for publishing such documents.

Milestones:
   - Submit 5033bis to IESG for publication.
   - Submit an Informational RFC analyzing the published standard congestion controllers