Re: [dtn] I-D Action: draft-ietf-dtn-tcpclv4-11.txt

All,
The latest draft -11 of TCPCLv4 makes some structural changes, based on feedback from Joerg Ott, to remove the XFER_INIT message and instead embed the transfer extension items within the starting XFER_SEGMENT message. The total-bundle-length field which was in the XFER_INIT message has been moved into a Transfer Length extension item. The total extension length is also reduced from a 64-bit to 32-bit integer to agree with the statements about avoiding large extension data. I replaced some MAY with SHOULD and some SHOULD with SHALL to make the behavior more deterministic.

Removing the XFER_INIT message reduces state machine complexity on both the transmitter and the receiver, and reduces per-transmission overhead slightly (from 39 octets to 37 octets when the Transfer Length extension is used to provide equivalent information).

Relocating the total-transfer-length into an extension item makes the simplest CL operating mode have fewer logical paths and allows for the least-overhead for one-segment-per-transfer operating mode (from 39 octets to 22 octets per-transfer).
________________________________
From: dtn <dtn-bounces@ietf.org> on behalf of internet-drafts@ietf.org <internet-drafts@ietf.org>
Sent: Friday, March 1, 2019 00:10
To: i-d-announce@ietf.org
Cc: dtn@ietf.org
Subject: [dtn] I-D Action: draft-ietf-dtn-tcpclv4-11.txt

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Delay/Disruption Tolerant Networking WG of the IETF.

        Title           : Delay-Tolerant Networking TCP Convergence Layer Protocol Version 4
        Authors         : Brian Sipos
                          Michael Demmer
                          Joerg Ott
                          Simon Perreault
        Filename        : draft-ietf-dtn-tcpclv4-11.txt
        Pages           : 52
        Date            : 2019-02-28

Abstract:
   This document describes a revised protocol for the TCP-based
   convergence layer (TCPCL) for Delay-Tolerant Networking (DTN).  The
   protocol revision is based on implementation issues in the original
   TCPCL Version 3 of RFC7242 and updates to the Bundle Protocol
   contents, encodings, and convergence layer requirements in Bundle
   Protocol Version 7.  Specifically, the TCPCLv4 uses CBOR-encoded BPv7
   bundles as its service data unit being transported and provides a
   reliable transport of such bundles.  Several new IANA registries are
   defined for TCPCLv4 which define some behaviors inherited from
   TCPCLv3 but with updated encodings and/or semantics.

The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-ietf-dtn-tcpclv4/

There are also htmlized versions available at:
https://tools.ietf.org/html/draft-ietf-dtn-tcpclv4-11
https://datatracker.ietf.org/doc/html/draft-ietf-dtn-tcpclv4-11

A diff from the previous version is available at:
https://www.ietf.org/rfcdiff?url2=draft-ietf-dtn-tcpclv4-11

Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at tools.ietf.org.

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

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