LLN Fragment Forwarding and Recovery
draft-thubert-6lo-forwarding-fragments-07
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6lo P. Thubert, Ed.
Internet-Draft Cisco Systems
Updates: 4944 (if approved) J. Hui
Intended status: Standards Track Nest Labs
Expires: January 25, 2018 July 24, 2017
LLN Fragment Forwarding and Recovery
draft-thubert-6lo-forwarding-fragments-07
Abstract
Considering that an LLN frame can have a MAC payload below 100 bytes,
an IPv6 packet might be fragmented into more than 10 fragments at the
6LoWPAN layer. In a 6LoWPAN mesh-under network, the fragments can be
forwarded individually across the mesh, whereas a route-over mesh
network, a fragmented 6LoWPAN packet must be reassembled at every
hop, which causes latency and congestion. This draft introduces a
simple protocol to forward individual fragments across a route-over
mesh network, and, regardless of the type of mesh, recover the loss
of individual fragments across the mesh and protect the network
against bloat with a minimal flow control.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 25, 2018.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
Thubert & Hui Expires January 25, 2018 [Page 1]
Internet-Draft LLN Fragment Forwarding and Recovery July 2017
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Updating RFC 4944 . . . . . . . . . . . . . . . . . . . . . . 3
3. Terminology and Referenced Work . . . . . . . . . . . . . . . 4
4. New Dispatch types and headers . . . . . . . . . . . . . . . 5
4.1. Recoverable Fragment Dispatch type and Header . . . . . . 5
4.2. RFRAG Acknowledgment Dispatch type and Header . . . . . . 7
5. Fragments Recovery . . . . . . . . . . . . . . . . . . . . . 8
6. Forwarding Fragments . . . . . . . . . . . . . . . . . . . . 10
6.1. Upon the first fragment . . . . . . . . . . . . . . . . . 10
6.2. Upon the next fragments . . . . . . . . . . . . . . . . . 11
6.3. Upon the RFRAG Acknowledgments . . . . . . . . . . . . . 12
7. Security Considerations . . . . . . . . . . . . . . . . . . . 13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
10.1. Normative References . . . . . . . . . . . . . . . . . . 13
10.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. Rationale . . . . . . . . . . . . . . . . . . . . . 15
Appendix B. Requirements . . . . . . . . . . . . . . . . . . . . 17
Appendix C. Considerations On Flow Control . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction
In most Low Power and Lossy Network (LLN) applications, the bulk of
the traffic consists of small chunks of data (in the order few bytes
to a few tens of bytes) at a time. Given that an IEEE Std. 802.15.4
[IEEE.802.15.4] frame can carry 74 bytes or more in all cases,
fragmentation is usually not required. However, and though this
happens only occasionally, a number of mission critical applications
do require the capability to transfer larger chunks of data, for
instance to support a firmware upgrades of the LLN nodes or an
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