draft-ietf-lwig-6lowpan-virtual-reassembly-01.txt   draft-ietf-lwig-6lowpan-virtual-reassembly-02.txt 
Network Working Group C. Bormann Network Working Group C. Bormann
Internet-Draft Universitaet Bremen TZI Internet-Draft Universitaet Bremen TZI
Intended status: Informational T. Watteyne Intended status: Informational T. Watteyne
Expires: September 12, 2019 Analog Devices Expires: September 10, 2020 Analog Devices
March 11, 2019 March 09, 2020
Virtual reassembly buffers in 6LoWPAN Virtual reassembly buffers in 6LoWPAN
draft-ietf-lwig-6lowpan-virtual-reassembly-01 draft-ietf-lwig-6lowpan-virtual-reassembly-02
Abstract Abstract
When employing adaptation layer fragmentation in 6LoWPAN, it may be When employing adaptation layer fragmentation in 6LoWPAN, it may be
beneficial for a forwarder not to have to reassemble each packet in beneficial for a forwarder not to have to reassemble each packet in
its entirety before forwarding it. its entirety before forwarding it.
This has been always possible with the original fragmentation design This has been always possible with the original fragmentation design
of RFC 4944. Apart from a brief mention of the way to do this in of RFC 4944. Apart from a brief mention of the way to do this in
Section 2.5.2 of the 6LoWPAN book, this has not been extensively Section 2.5.2 of the 6LoWPAN book, this has not been extensively
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This Internet-Draft will expire on September 12, 2019. This Internet-Draft will expire on September 10, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Reassembly buffers . . . . . . . . . . . . . . . . . . . . . 3 2. Reassembly buffers . . . . . . . . . . . . . . . . . . . . . 3
3. Virtual reassembly . . . . . . . . . . . . . . . . . . . . . 3 3. Virtual reassembly . . . . . . . . . . . . . . . . . . . . . 3
4. Header compression . . . . . . . . . . . . . . . . . . . . . 4 4. Header compression . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Security considerations . . . . . . . . . . . . . . . . . . . 4 6. Security considerations . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . 4 7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 5 7.2. Informative References . . . . . . . . . . . . . . . . . 5
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 5 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction 1. Introduction
6LoWPAN [RFC4944] is the seminal standard for the transmission of 6LoWPAN [RFC4944] is the seminal standard for the transmission of
IPv6 packets over IEEE 802.15.4 networks and has served as a IPv6 packets over IEEE 802.15.4 networks and has served as a
blueprint for a number of related standards addressing low-power blueprint for a number of related standards addressing low-power
radios and other IoT connectivity solutions (the "6Lo suite"). radios and other IoT connectivity solutions (the "6Lo suite").
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When employing adaptation layer fragmentation on constrained-node When employing adaptation layer fragmentation on constrained-node
networks [RFC7228], it may be beneficial for a forwarder not to have networks [RFC7228], it may be beneficial for a forwarder not to have
to reassemble each packet in its entirety before forwarding it. to reassemble each packet in its entirety before forwarding it.
This has been always possible with the original fragmentation design This has been always possible with the original fragmentation design
of RFC 4944. Apart from a brief mention of the way to do this in of RFC 4944. Apart from a brief mention of the way to do this in
Section 2.5.2 of the 6LoWPAN book [BOOK], this has not been Section 2.5.2 of the 6LoWPAN book [BOOK], this has not been
extensively described in the literature. The present document extensively described in the literature. The present document
attempts to fill that gap. attempts to fill that gap.
[I-D.watteyne-6lo-minimal-fragment] provides additional context and [I-D.ietf-6lo-minimal-fragment] provides additional context and
discussion about handling fragment forwarding in the 6Lo standards discussion about handling fragment forwarding in the 6Lo standards
suite. suite.
2. Reassembly buffers 2. Reassembly buffers
An adaptation layer implementation for 6LoWPAN needs to perform An adaptation layer implementation for 6LoWPAN needs to perform
reassembly of every fragmented packet received in order to be able to reassembly of every fragmented packet received in order to be able to
forward the packet (re-fragmenting it in the process). forward the packet (re-fragmenting it in the process).
A reassembly buffer for 6LoWPAN contains: A reassembly buffer for 6LoWPAN contains:
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here.) This makes sure an additional fragment only needs to be sent here.) This makes sure an additional fragment only needs to be sent
if the header expansion during forwarding would have created an if the header expansion during forwarding would have created an
additional fragment with full reassembly as well. additional fragment with full reassembly as well.
5. IANA Considerations 5. IANA Considerations
This document makes no requests of IANA. This document makes no requests of IANA.
6. Security considerations 6. Security considerations
TBD There are many security considerations with using fragmentation in
the first place, even with adaptation layer fragmentation (which is
not accessible outside the range of that adaptation layer). Some of
the more specific ones are documented in
[I-D.ietf-6lo-minimal-fragment] and will not be duplicated here.
In general, sending on fragments early from a node will relieve the
node that is doing the forwarding, but put additional onus on the
next node. This may or may not be in favor of an attacker.
7. References 7. References
7.1. Normative References 7.1. Normative References
[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
"Transmission of IPv6 Packets over IEEE 802.15.4 "Transmission of IPv6 Packets over IEEE 802.15.4
Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007, Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
<https://www.rfc-editor.org/info/rfc4944>. <https://www.rfc-editor.org/info/rfc4944>.
7.2. Informative References 7.2. Informative References
[BOOK] Shelby, Z. and C. Bormann, "6LoWPAN", John Wiley & Sons, [BOOK] Shelby, Z. and C. Bormann, "6LoWPAN", John Wiley & Sons,
Ltd monograph, DOI 10.1002/9780470686218, November 2009. Ltd monograph, DOI 10.1002/9780470686218, November 2009.
[I-D.watteyne-6lo-minimal-fragment] [I-D.ietf-6lo-minimal-fragment]
Watteyne, T., Bormann, C., and P. Thubert, "LLN Minimal Watteyne, T., Thubert, P., and C. Bormann, "On Forwarding
Fragment Forwarding", draft-watteyne-6lo-minimal- 6LoWPAN Fragments over a Multihop IPv6 Network", draft-
fragment-02 (work in progress), July 2018. ietf-6lo-minimal-fragment-14 (work in progress), March
2020.
[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC6282, September 2011, DOI 10.17487/RFC6282, September 2011,
<https://www.rfc-editor.org/info/rfc6282>. <https://www.rfc-editor.org/info/rfc6282>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228, Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014, DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>. <https://www.rfc-editor.org/info/rfc7228>.
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