Designating 6LBR for IID Assignment
draft-rashid-6lo-iid-assignment-00
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| Authors | Abdur Rashid Sangi , Mach Chen , Charles E. Perkins | ||
| Last updated | 2016-03-16 | ||
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draft-rashid-6lo-iid-assignment-00
6lo AR. Sangi
Internet-Draft M. Chen
Intended status: Standards Track Huawei Technologies
Expires: September 17, 2016 C. Perkins
Futurewei
March 16, 2016
Designating 6LBR for IID Assignment
draft-rashid-6lo-iid-assignment-00
Abstract
In IPv6 Stateless Address Autoconfiguration (SLAAC), use of a random
interface identifier (IID) is a common practice to promote privacy.
If there are a very large number of nodes, as has been discussed in
several use cases, the effect will to proportionately increase the
number of IIDs. A duplicate address detection (DAD cycle) is needed
for each configured IID, introducing more and more overhead into the
network. Each failed DAD requires the initiating node to regenerate
a new IID and undergo the DAD cycle again. This document proposes an
optimized approach that requires 6LBR (6LoWPAN Border Router) to
provide a unique IID, avoiding the potential duplication.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on September 17, 2016.
Copyright Notice
Copyright (c) 2016 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
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(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. IID Assignment by 6LBR . . . . . . . . . . . . . . . . . . . 3
3.1. Extended Confirmation Message . . . . . . . . . . . . . . 5
3.2. Extended Address Registration Option . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
4.1. Additions of EDAC Message and EARO Option . . . . . . . . 6
4.2. Additions to Status Field . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.1. Normative References . . . . . . . . . . . . . . . . . . 7
6.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
IPv6 addresses in SLAAC are formed by concatenating a network prefix,
acquired from Router Advertisement (RA) messages, with a locally
generated IID [RFC4862], [RFC2464]. Since the best method for
generating IIDs depends on the nature of networks, none of the
proposed mechanisms is considered a default mechanism [RFC4941],
[RFC7217]. Using neighbour discovery (ND), the uniqueness of newly
generated IID is verified [RFC6775]. 6LBR ensures the duplication
detection, and replies with a status. A failed DAD would require the
initiating 6LN (6LoWPAN Node) to regenerate an IID and undergo
another DAD cycle, until either 6LN succeeds or reaches its maximum
number of retries[RFC6775].
A locally generated IID can be derived from embedded IEEE identifier
[RFC4941] or randomly (based on a few variables) [RFC7217]. MAC
reuse is far common than assumed [RFC7217], and IIDs derived from MAC
address are likely to cause more than the expected number of DAD
failures. As soon as the 6LN generates an IID, it sends the NS
(Neighbor Solicitation) message to 6LR (LLN Router) and 6LR proceeds
with the address duplication request routine with 6LBR by sending an
ICMPv6 based DAR (Duplicate Address Request) message. An LN sends
out a NS after checking its local cache for duplication; before
proceeding with DAR, the 6LR also protects against address
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duplication within a locally maintained Neighbor Cache Entry (NCE)
[RFC7217].
[RFC5548], [RFC5827] discuss use cases including huge numbers of
nodes and vast scale networks. The arbitrary use of IIDs resolves
the privacy concerns of participating node. A simple NS supposedly
targeted to a very small group of nodes MAY ends-up polluting whole
wireless bandwidth [I-D.vyncke-6man-mcast-not-efficient]. Multicast
NS and NA are much more frequent in large scale radio environment
with mobile devices [I-D.thubert-6lo-backbone-router]. Additionally,
as the IIDs are periodically changed for privacy, the probability
becomes high for a duplicate IIDs that would results in DAD failure
and repeated cycles.
This document describes optimization to 6LoWPAN ND by enabling 6LBR
to grant a unique IID for failed DAD.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119]. Additionally, this document uses terminology from
[RFC6775], [RFC2464], [I-D.ietf-6man-default-iids], and
[I-D.ietf-6man-ipv6-address-generation-privacy]. This document also
uses the following terms:
RID: Random identifier.
PRF: Pseudo random function.
LSB: Least significant bit.
EDAC: Extended duplicate address confirmation.
EARO: Extended address registration option.
3. IID Assignment by 6LBR
MAC driven IIDs [RFC2464] reduce or eliminate the the need for DAD,
but in practice such IID generation is discouraged
([I-D.ietf-6man-default-iids],
[I-D.ietf-6man-ipv6-address-generation-privacy]), as common privacy
concerns still persist, for instance:
o Network activity correlation,
o Location tracking,
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o Address scanning, and
o Device-specific vulnerability exploitation.
Moreover, multiple approaches are proposed to suit different network
constraints. Considering the scalability of a network and enabling
6LBR to suggest an IID, this draft proposes another IID generating
[RFC7217] approach to support periodically changing IIDs.
RID (Random Identifier) :=
|Prefix|Interface Index|N/W ID|DAD Counter|Randomized Secret Key|
\ /
\ /
\ /
+--------+--------+--------+
| Hash Function |
+--------+--------+--------+
/ \
/ \
Extract 64 LSBs
Figure 1: Using RFC7217 to generate IID
In case DAD fails, the 6LBR will use public values for Prefix,
Interface Index, and Network ID; the remaining two variables (DAD
Counter, Randomized Private Key) are local values. Neighbor
solicitation using link-local address cannot be avoided, but only the
newly generated IID needs to be passed on to LN (by way of relevant
6LR).
6LN 6LR 6LBR
| | |
1. | --- NS with Address Reg --> | |
| [ARO + SLLAO] | |
| | |
2. | | ---------- DAR ---------> |
| | |
3. | | <--------- EDAC --------- |
| | |
4. | <-- NA with Address Reg --- | |
| [EARO with Status] | |
Figure 2: DAD cycle when 6LBR generates an IID
The Approach in this draft is of reactive nature rather than
proactive. 6LBR only replies with locally generated IID when DAD
fails.
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3.1. Extended Confirmation Message
The Prefix is the same throughout each LoWPAN network. This draft
extends the DAC:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status | Reserved | Registration Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ EUI-64 +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ 6LBR Generated IID +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Extended Duplication Address Confirmation
The fields are similar to DAC in [RFC6775] except:
Type: 159
6LBR Generated IID: 64 bit IID generated by 6LBR.
3.2. Extended Address Registration Option
ARO and EARO can ONLY be initiated by host and 6LR, respectively.
[RFC6775] expects the reply of a host initiated ARO from 6LR with
same ARO except the changed status bit to indicate the duplication
result. EARO is introduced in this document and 6LR can send out
this option if it receives EDAC instead of DAC from 6LBR.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length = 2 | Status | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Registration Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ EUI-64 +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ 6LBR Generated IID +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Extended Address Registration Option
The fields are similar to ARO in [RFC6775] except:
Type: 36
6LBR Generated IID: a 64 bit IID generated by 6LBR.
4. IANA Considerations
4.1. Additions of EDAC Message and EARO Option
The document requires one new ICMPv6 "type" number under the
subregistry "ICMPv6 "type" Numbers":
o Extended Duplicate Address Confirmation (159)
This document requires a new ND option type under the subregistry
"IPv6 Neighbor Discovery Option Formats":
o Extended Address Registration Option (36)
4.2. Additions to Status Field
IANA is required to assign two new values to the Status bit in
Address Registration Option under the sub registry "IPv6 Neighbor
Discovery Option Formats":
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+--------+--------------------------------------------+
| Status | Description |
+--------+--------------------------------------------+
| 0 | Success |
| 1 | Duplicate Address |
| 2 | Neighbor Cache Full |
| 3 | 6LBR generated IID |
| 4-255 | Allocated using Standards Action [RFC5226] |
+--------+--------------------------------------------+
Addition to Status bits
5. Security Considerations
TBD
6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet
Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998,
<http://www.rfc-editor.org/info/rfc2464>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<http://www.rfc-editor.org/info/rfc4861>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007,
<http://www.rfc-editor.org/info/rfc4862>.
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy
Extensions for Stateless Address Autoconfiguration in
IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007,
<http://www.rfc-editor.org/info/rfc4941>.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012,
<http://www.rfc-editor.org/info/rfc6775>.
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[RFC7217] Gont, F., "A Method for Generating Semantically Opaque
Interface Identifiers with IPv6 Stateless Address
Autoconfiguration (SLAAC)", RFC 7217,
DOI 10.17487/RFC7217, April 2014,
<http://www.rfc-editor.org/info/rfc7217>.
6.2. Informative References
[I-D.ietf-6man-default-iids]
Gont, F., Cooper, A., Thaler, D., and S. LIU,
"Recommendation on Stable IPv6 Interface Identifiers",
draft-ietf-6man-default-iids-10 (work in progress),
February 2016.
[I-D.ietf-6man-ipv6-address-generation-privacy]
Cooper, A., Gont, F., and D. Thaler, "Privacy
Considerations for IPv6 Address Generation Mechanisms",
draft-ietf-6man-ipv6-address-generation-privacy-08 (work
in progress), September 2015.
[I-D.thubert-6lo-backbone-router]
Thubert, P., "IPv6 Backbone Router", draft-thubert-6lo-
backbone-router-03 (work in progress), November 2015.
[I-D.vyncke-6man-mcast-not-efficient]
Vyncke, E., Thubert, P., Levy-Abegnoli, E., and A.
Yourtchenko, "Why Network-Layer Multicast is Not Always
Efficient At Datalink Layer", draft-vyncke-6man-mcast-not-
efficient-01 (work in progress), February 2014.
[RFC5548] Dohler, M., Ed., Watteyne, T., Ed., Winter, T., Ed., and
D. Barthel, Ed., "Routing Requirements for Urban Low-Power
and Lossy Networks", RFC 5548, DOI 10.17487/RFC5548, May
2009, <http://www.rfc-editor.org/info/rfc5548>.
[RFC5827] Allman, M., Avrachenkov, K., Ayesta, U., Blanton, J., and
P. Hurtig, "Early Retransmit for TCP and Stream Control
Transmission Protocol (SCTP)", RFC 5827,
DOI 10.17487/RFC5827, May 2010,
<http://www.rfc-editor.org/info/rfc5827>.
Authors' Addresses
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Abdur Rashid Sangi
Huawei Technologies
No.156 Beiqing Rd. Haidian District
Beijing 100095
P.R. China
Email: rashid.sangi@huawei.com
Mach (Guoyi)Chen
Huawei Technologies
No.156 Beiqing Rd. Haidian District
Beijing 100095
P.R. China
Email: mach.chen@huawei.com
Charles E. Perkins
Futurewei
2330 Central Expressway
Santa Clara 95050
USA
Email: charliep@computer.org
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