On Forwarding 6LoWPAN Fragments over a Multihop IPv6 Network
draft-ietf-6lo-minimal-fragment-07
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2019-11-28
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draft-watteyne-6lo-minimal-fragment
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Carles Gomez
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Suresh Krishnan
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Carles Gomez <carlesgo@entel.upc.edu>
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6lo T. Watteyne, Ed.
Internet-Draft Analog Devices
Intended status: Standards Track P. Thubert, Ed.
Expires: 31 May 2020 Cisco Systems
C. Bormann
Universitaet Bremen TZI
28 November 2019
On Forwarding 6LoWPAN Fragments over a Multihop IPv6 Network
draft-ietf-6lo-minimal-fragment-07
Abstract
This document introduces the capability to forward 6LoWPAN fragments.
This method reduces the latency and increases end-to-end reliability
in route-over forwarding. It is the companion to using virtual
reassembly buffers which is a pure implementation technique.
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 https://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 31 May 2020.
Copyright Notice
Copyright (c) 2019 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 (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Simplified BSD License text
Watteyne, et al. Expires 31 May 2020 [Page 1]
Internet-Draft fragment forwarding November 2019
as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Referenced Work . . . . . . . . . . . . . . . . . . . . . 3
2.3. New Terms . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Overview of 6LoWPAN Fragmentation . . . . . . . . . . . . . . 4
4. Limits of Per-Hop Fragmentation and Reassembly . . . . . . . 6
4.1. Latency . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.2. Memory Management and Reliability . . . . . . . . . . . . 6
5. Forwarding Fragments . . . . . . . . . . . . . . . . . . . . 7
6. Virtual Reassembly Buffer (VRB) Implementation . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
10. Normative References . . . . . . . . . . . . . . . . . . . . 11
11. Informative References . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
The original 6LoWPAN fragmentation is defined in [RFC4944] and it is
implicitly defined for use over a single IP hop through possibly
multiple Layer-2 (mesh-under) hops in a meshed 6LoWPAN Network.
Although [RFC6282] updates [RFC4944], it does not redefine 6LoWPAN
fragmentation.
This means that over a Layer-3 (route-over) network, an IP packet is
expected to be reassembled at every hop at the 6LoWPAN sublayer,
pushed to Layer-3 to be routed, and then fragmented again if the next
hop is another similar 6LoWPAN link. This draft introduces an
alternate approach called 6LoWPAN Fragment Forwarding (FF) whereby an
intermediate node forwards a fragment as soon as it is received if
the next hop is a similar 6LoWPAN link. The routing decision is made
on the first fragment, which has all the IPv6 routing information.
The first fragment is forwarded immediately and a state is stored to
enable forwarding the next fragments along the same path.
Done right, 6LoWPAN Fragment Forwarding techniques lead to more
streamlined operations, less buffer bloat and lower latency. It may
be wasteful if some fragments are missing after the first one since
the first fragment will still continue till the 6LoWPAN endpoint that
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