On Forwarding 6LoWPAN Fragments over a Multihop IPv6 Network
draft-ietf-6lo-minimal-fragment-15

Document Type Active Internet-Draft (6lo WG)
Last updated 2020-07-06 (latest revision 2020-03-23)
Replaces draft-watteyne-6lo-minimal-fragment
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6lo                                                     T. Watteyne, Ed.
Internet-Draft                                            Analog Devices
Intended status: Standards Track                         P. Thubert, Ed.
Expires: 24 September 2020                                 Cisco Systems
                                                              C. Bormann
                                                 Universitaet Bremen TZI
                                                           23 March 2020

      On Forwarding 6LoWPAN Fragments over a Multihop IPv6 Network
                   draft-ietf-6lo-minimal-fragment-15

Abstract

   This document provides generic rules to enable the forwarding of
   6LoWPAN fragment over a route-over network.  Forwarding fragments can
   improve both the end-to-end latency and reliability, and reduce the
   buffer requirements in intermediate nodes; it may be implemented
   using RFC 4944 and virtual reassembly buffers.

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
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   This Internet-Draft will expire on 24 September 2020.

Copyright Notice

   Copyright (c) 2020 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 24 September 2020               [Page 1]
Internet-Draft             fragment forwarding                March 2020

   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.  Limitations 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 . . . . . . . . . . . . . . . . . . . . .  11
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  11
   10. Normative References  . . . . . . . . . . . . . . . . . . . .  11
   11. Informative References  . . . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   The original 6LoWPAN fragmentation is defined in [RFC4944] for use
   over a single Layer 3 hop, though possibly multiple Layer 2 hops in a
   mesh-under network, and was not modified by the [RFC6282] update.
   6LoWPAN operations including fragmentation depend on a Link-Layer
   security that prevents any rogue access to the network.

   In a route-over 6LoWPAN network, an IP packet is expected to be
   reassembled at each intermediate hop, uncompressed, pushed to Layer 3
   to be routed, and then compressed and fragmented again.  This draft
   introduces an alternate approach called 6LoWPAN Fragment Forwarding
   (6FF) whereby an intermediate node forwards a fragment (or the bulk
   thereof, MTU permitting) without reassembling if the next hop is a
   similar 6LoWPAN link.  The routing decision is made on the first
   fragment of the datagram, which has 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.  But it
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