draft-ietf-6lo-minimal-fragment-08.txt   draft-ietf-6lo-minimal-fragment-09.txt 
6lo T. Watteyne, Ed. 6lo T. Watteyne, Ed.
Internet-Draft Analog Devices Internet-Draft Analog Devices
Intended status: Standards Track P. Thubert, Ed. Intended status: Standards Track P. Thubert, Ed.
Expires: 2 August 2020 Cisco Systems Expires: 3 August 2020 Cisco Systems
C. Bormann C. Bormann
Universitaet Bremen TZI Universitaet Bremen TZI
30 January 2020 31 January 2020
On Forwarding 6LoWPAN Fragments over a Multihop IPv6 Network On Forwarding 6LoWPAN Fragments over a Multihop IPv6 Network
draft-ietf-6lo-minimal-fragment-08 draft-ietf-6lo-minimal-fragment-09
Abstract Abstract
This document introduces the capability to forward 6LoWPAN fragments. This document introduces the capability to forward 6LoWPAN fragments.
This method reduces the latency and increases end-to-end reliability This method reduces the latency and increases end-to-end reliability
in route-over forwarding. It is the companion to using virtual in route-over forwarding. It is the companion to using virtual
reassembly buffers which is a pure implementation technique. reassembly buffers which is a pure implementation technique.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on 2 August 2020. This Internet-Draft will expire on 3 August 2020.
Copyright Notice Copyright Notice
Copyright (c) 2020 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.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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on the first fragment before it attempts to send the next fragments, on the first fragment before it attempts to send the next fragments,
and that it should abort the datagram and release its state if it and that it should abort the datagram and release its state if it
fails to send the first fragment. fails to send the first fragment.
One benefit of Fragment Forwarding is that the memory that is used to One benefit of Fragment Forwarding is that the memory that is used to
store the packet is now distributed along the path, which limits the store the packet is now distributed along the path, which limits the
buffer bloat effect. Multiple fragments may progress in parallel buffer bloat effect. Multiple fragments may progress in parallel
along the network as long as they do not interfere. An associated along the network as long as they do not interfere. An associated
caveat is that on a half duplex radio, if node A sends the next caveat is that on a half duplex radio, if node A sends the next
fragment at the same time as node B forwards the previous fragment to fragment at the same time as node B forwards the previous fragment to
a node C down the path then node B will miss the next fragment. If a node C down the path then node B will miss the next fragment from
node C forwards the previous fragment to a node D at the same time node A. If node C forwards the previous fragment to a node D at the
and on the same frequency as node A sends the next fragment to node same time and on the same frequency as node A sends the next fragment
B, this may result in a hidden terminal problem at B whereby the to node B, this may result in a hidden terminal problem at B whereby
transmission from C interferes with that from A unbeknownst of node the transmission from C interferes with that from A unbeknownst of
A. It results that consecutive fragments must be reasonably spaced node A. It results that consecutive fragments must be reasonably
in order to avoid the 2 forms of collision described above. A node spaced in order to avoid the 2 forms of collision described above. A
that has multiple packets or fragments to send via different next-hop node that has multiple packets or fragments to send via different
routers may interleave the messages in order to alleviate those next-hop routers may interleave the messages in order to alleviate
effects. those effects.
6. Virtual Reassembly Buffer (VRB) Implementation 6. Virtual Reassembly Buffer (VRB) Implementation
Virtual Reassembly Buffer (VRB) is the implementation technique Virtual Reassembly Buffer (VRB) is the implementation technique
described in [LWIG-VRB] in which a forwarder does not reassemble each described in [LWIG-VRB] in which a forwarder does not reassemble each
packet in its entirety before forwarding it. packet in its entirety before forwarding it.
VRB overcomes the limits listed in Section 4. Nodes do not wait for VRB overcomes the limits listed in Section 4. Nodes do not wait for
the last fragment before forwarding, reducing end-to-end latency. the last fragment before forwarding, reducing end-to-end latency.
Similarly, the memory footprint of VRB is just the VRB table, Similarly, the memory footprint of VRB is just the VRB table,
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8. IANA Considerations 8. IANA Considerations
No requests to IANA are made by this document. No requests to IANA are made by this document.
9. Acknowledgments 9. Acknowledgments
The authors would like to thank Carles Gomez Montenegro, Yasuyuki The authors would like to thank Carles Gomez Montenegro, Yasuyuki
Tanaka, Ines Robles and Dave Thaler for their in-depth review of this Tanaka, Ines Robles and Dave Thaler for their in-depth review of this
document and improvement suggestions. Also many thanks to Georgies document and improvement suggestions. Also many thanks to Georgies
Papadopoulos and Dominique Barthel for their own reviews, and to Papadopoulos and Dominique Barthel for their own reviews, and to
Joerg Ott who helped through the IESG steps. Joerg Ott and Francesca Palombini For their constructive reviews
through the IESG process.
10. Normative References 10. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[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>.
[LWIG-VRB] Bormann, C. and T. Watteyne, "Virtual reassembly buffers
in 6LoWPAN", Work in Progress, Internet-Draft, draft-ietf-
lwig-6lowpan-virtual-reassembly-01, 11 March 2019,
<https://tools.ietf.org/html/draft-ietf-lwig-6lowpan-
virtual-reassembly-01>.
[FRAG-RECOV]
Thubert, P., "6LoWPAN Selective Fragment Recovery", Work
in Progress, Internet-Draft, draft-ietf-6lo-fragment-
recovery-08, 28 November 2019,
<https://tools.ietf.org/html/draft-ietf-6lo-fragment-
recovery-08>.
11. Informative References 11. Informative References
[RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6 [RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6
over Low-Power Wireless Personal Area Networks (6LoWPANs): over Low-Power Wireless Personal Area Networks (6LoWPANs):
Overview, Assumptions, Problem Statement, and Goals", Overview, Assumptions, Problem Statement, and Goals",
RFC 4919, DOI 10.17487/RFC4919, August 2007, RFC 4919, DOI 10.17487/RFC4919, August 2007,
<https://www.rfc-editor.org/info/rfc4919>. <https://www.rfc-editor.org/info/rfc4919>.
[RFC4963] Heffner, J., Mathis, M., and B. Chandler, "IPv4 Reassembly [RFC4963] Heffner, J., Mathis, M., and B. Chandler, "IPv4 Reassembly
Errors at High Data Rates", RFC 4963, Errors at High Data Rates", RFC 4963,
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DOI 10.17487/RFC6550, March 2012, DOI 10.17487/RFC6550, March 2012,
<https://www.rfc-editor.org/info/rfc6550>. <https://www.rfc-editor.org/info/rfc6550>.
[FRAG-ILE] Bonica, R., Baker, F., Huston, G., Hinden, R., Troan, O., [FRAG-ILE] Bonica, R., Baker, F., Huston, G., Hinden, R., Troan, O.,
and F. Gont, "IP Fragmentation Considered Fragile", Work and F. Gont, "IP Fragmentation Considered Fragile", Work
in Progress, Internet-Draft, draft-ietf-intarea-frag- in Progress, Internet-Draft, draft-ietf-intarea-frag-
fragile-17, 30 September 2019, fragile-17, 30 September 2019,
<https://tools.ietf.org/html/draft-ietf-intarea-frag- <https://tools.ietf.org/html/draft-ietf-intarea-frag-
fragile-17>. fragile-17>.
[LWIG-VRB] Bormann, C. and T. Watteyne, "Virtual reassembly buffers
in 6LoWPAN", Work in Progress, Internet-Draft, draft-ietf-
lwig-6lowpan-virtual-reassembly-01, 11 March 2019,
<https://tools.ietf.org/html/draft-ietf-lwig-6lowpan-
virtual-reassembly-01>.
[FRAG-RECOV]
Thubert, P., "6LoWPAN Selective Fragment Recovery", Work
in Progress, Internet-Draft, draft-ietf-6lo-fragment-
recovery-08, 28 November 2019,
<https://tools.ietf.org/html/draft-ietf-6lo-fragment-
recovery-08>.
[ARTICLE] Tanaka, Y., Minet, P., and T. Watteyne, "6LoWPAN Fragment [ARTICLE] Tanaka, Y., Minet, P., and T. Watteyne, "6LoWPAN Fragment
Forwarding", IEEE Communications Standards Magazine , Forwarding", IEEE Communications Standards Magazine ,
2019. 2019.
Authors' Addresses Authors' Addresses
Thomas Watteyne (editor) Thomas Watteyne (editor)
Analog Devices Analog Devices
32990 Alvarado-Niles Road, Suite 910 32990 Alvarado-Niles Road, Suite 910
Union City, CA 94587 Union City, CA 94587
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