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
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.
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.