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Delay-Tolerant Networking TCP Convergence-Layer Protocol Version 4
RFC 9174

Approval announcement
Draft of message to be sent after approval:


From: The IESG <>
To: IETF-Announce <>
Cc: Edward Birrane <>, The IESG <>,,,,,,
Subject: Protocol Action: 'Delay-Tolerant Networking TCP Convergence Layer Protocol Version 4' to Proposed Standard (draft-ietf-dtn-tcpclv4-26.txt)

The IESG has approved the following document:
- 'Delay-Tolerant Networking TCP Convergence Layer Protocol Version 4'
  (draft-ietf-dtn-tcpclv4-26.txt) as Proposed Standard

This document is the product of the Delay/Disruption Tolerant Networking
Working Group.

The IESG contact persons are Martin Duke and Magnus Westerlund.

A URL of this Internet Draft is:

Ballot Text

Technical Summary

This document describes the Delay-Tolerant Networking TCP Convergence Layer 
Protocol Version 4 (TCPCLv4) for use with the Bundle Protocol Version 7 (BPv7) 

The BPv7 implements a store-and-forward overlay network suitable for 
delay-tolerant message exchange. The protocol data unit for the BPv7 is the 
"bundle". BPv7 agents require convergence layer adapters (CLAs) to send and 
receive "bundles" using the service of some "native" link, network, or 
Internet protocol. Both the BPv7 and its CLAs reside at the application layer 
of the Internet model protocol stack [RFC1122]. 

The TCPCLv4 describes a CLA that sends and received bundles using the well-known 
Transmission Control Protocol (TCP). This specification describes the format and 
processing of the protocol data units passed between entities participating in 
TCPCLv4 communications.  

Working Group Summary:

TCPCLv4 is descended from an experimental IRTF specification TCPCLv3 [RFC7242]. 
Implementation experience with TCPCLv3 identified limitations such as ambiguity 
in bundle acknowledgment and refusal, non-normative discussion on how to 
incorporate TLS, and minor inefficiencies associated with sequencing. TCPCLv4 
was created to address those limitations and prepare the specification for 
non-experimental use. Technical discussions over the last 3 years have been
well informed and focused on TLS negotiations, overall protocol agent state 
machines, and a protocol extension mechanism. There is no controversy related 
to the adoption of the specification; DTNWG consensus on the draft is strong. 

Document Quality:

The workflow for TCPCLv4 remained largely unchanged from that of TCPCLv3 for 
which reference implementations exist. Co-author B. Sipos has created a 
reference implementation of TCPCLv4 to demonstrate features and ensure the 
clarity of the draft. Much of the recent review provided by the DTNWG focused 
on increasing the overall clarity of the specification to ensure no ambiguities 
exist for implementers. There have been no problems discovered with the 
reference implementation for this draft. 


The Document Shepherd is Ed Birrane.

The Responsible Area Director is Magnus Westerlund.

RFC Editor Note