< draft-ietf-6lo-backbone-router-10.txt   draft-ietf-6lo-backbone-router-11.txt >
6lo P. Thubert, Ed. 6lo P. Thubert, Ed.
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Updates: 4861, 8505 (if approved) C. Perkins Updates: 6775, 8505 (if approved) C. Perkins
Intended status: Standards Track Futurewei Intended status: Standards Track Futurewei
Expires: July 20, 2019 E. Levy-Abegnoli Expires: August 8, 2019 E. Levy-Abegnoli
Cisco Systems Cisco Systems
January 16, 2019 February 4, 2019
IPv6 Backbone Router IPv6 Backbone Router
draft-ietf-6lo-backbone-router-10 draft-ietf-6lo-backbone-router-11
Abstract Abstract
This document updates RFC 4861 and RFC 8505 in order to enable proxy This document updates RFC 4861 and RFC 8505 in order to enable proxy
services for IPv6 Neighbor Discovery by Routing Registrars called services for IPv6 Neighbor Discovery by Routing Registrars called
Backbone Routers. Backbone Routers are placed along the wireless Backbone Routers. Backbone Routers are placed along the wireless
edge of a Backbone, and federate multiple wireless links to form a edge of a Backbone, and federate multiple wireless links to form a
single MultiLink Subnet. single MultiLink Subnet.
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 July 20, 2019. This Internet-Draft will expire on August 8, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 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 Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. BCP 14 . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. New Terms . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2. New Terms . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. Acronym Definitions . . . . . . . . . . . . . . . . . . . 6 2.3. Acronym Definitions . . . . . . . . . . . . . . . . . . . 6
2.4. References . . . . . . . . . . . . . . . . . . . . . . . 7 2.4. References . . . . . . . . . . . . . . . . . . . . . . . 7
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1. Updating RFC 6775 and RFC 8505 . . . . . . . . . . . . . 9 3.1. Updating RFC 6775 and RFC 8505 . . . . . . . . . . . . . 9
3.2. Access Link . . . . . . . . . . . . . . . . . . . . . . . 10 3.2. Access Link . . . . . . . . . . . . . . . . . . . . . . . 10
3.3. Route-Over Mesh . . . . . . . . . . . . . . . . . . . . . 11 3.3. Route-Over Mesh . . . . . . . . . . . . . . . . . . . . . 11
3.4. The Binding Table . . . . . . . . . . . . . . . . . . . . 12 3.4. The Binding Table . . . . . . . . . . . . . . . . . . . . 12
3.5. Primary and Secondary 6BBRs . . . . . . . . . . . . . . . 13 3.5. Primary and Secondary 6BBRs . . . . . . . . . . . . . . . 13
3.6. Using Optimistic DAD . . . . . . . . . . . . . . . . . . 13 3.6. Using Optimistic DAD . . . . . . . . . . . . . . . . . . 14
4. MultiLink Subnet Considerations . . . . . . . . . . . . . . . 14 4. MultiLink Subnet Considerations . . . . . . . . . . . . . . . 14
5. Optional 6LBR serving the MultiLink Subnet . . . . . . . . . 14 5. Optional 6LBR serving the MultiLink Subnet . . . . . . . . . 15
6. Using IPv6 ND Over the Backbone Link . . . . . . . . . . . . 15 6. Using IPv6 ND Over the Backbone Link . . . . . . . . . . . . 15
7. Routing Proxy Operations . . . . . . . . . . . . . . . . . . 15 7. Routing Proxy Operations . . . . . . . . . . . . . . . . . . 16
8. Bridging Proxy Operations . . . . . . . . . . . . . . . . . . 16 8. Bridging Proxy Operations . . . . . . . . . . . . . . . . . . 17
9. Creating and Maintaining a Binding . . . . . . . . . . . . . 17 9. Creating and Maintaining a Binding . . . . . . . . . . . . . 18
9.1. Operation on a Binding in Tentative State . . . . . . . . 19 9.1. Operation on a Binding in Tentative State . . . . . . . . 19
9.2. Operation on a Binding in Reachable State . . . . . . . . 20 9.2. Operation on a Binding in Reachable State . . . . . . . . 20
9.3. Operation on a Binding in Stale State . . . . . . . . . . 21 9.3. Operation on a Binding in Stale State . . . . . . . . . . 21
10. Registering Node Considerations . . . . . . . . . . . . . . . 21 10. Registering Node Considerations . . . . . . . . . . . . . . . 22
11. Security Considerations . . . . . . . . . . . . . . . . . . . 22 11. Security Considerations . . . . . . . . . . . . . . . . . . . 23
12. Protocol Constants . . . . . . . . . . . . . . . . . . . . . 22 12. Protocol Constants . . . . . . . . . . . . . . . . . . . . . 23
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23 14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 23 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 24
15.1. Normative References . . . . . . . . . . . . . . . . . . 23 15.1. Normative References . . . . . . . . . . . . . . . . . . 24
15.2. Informative References . . . . . . . . . . . . . . . . . 24 15.2. Informative References . . . . . . . . . . . . . . . . . 25
Appendix A. Possible Future Extensions . . . . . . . . . . . . . 27 Appendix A. Possible Future Extensions . . . . . . . . . . . . . 28
Appendix B. Applicability and Requirements Served . . . . . . . 27 Appendix B. Applicability and Requirements Served . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30
1. Introduction 1. Introduction
IEEE STD. 802.1 [IEEEstd8021] Ethernet Bridging provides an efficient IEEE STD. 802.1 [IEEEstd8021] Ethernet Bridging provides an efficient
and reliable broadcast service for wired networks; applications and and reliable broadcast service for wired networks; applications and
protocols have been built that heavily depend on that feature for protocols have been built that heavily depend on that feature for
their core operation. Unfortunately, Low-Power Lossy Networks (LLNs) their core operation. Unfortunately, Low-Power Lossy Networks (LLNs)
and local wireless networks generally do not provide the broadcast and local wireless networks generally do not provide the broadcast
capabilities of Ethernet Bridging in an economical fashion. capabilities of Ethernet Bridging in an economical fashion.
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6BBR: 6LoWPAN Backbone Router 6BBR: 6LoWPAN Backbone Router
6LBR: 6LoWPAN Border Router 6LBR: 6LoWPAN Border Router
6LN: 6LoWPAN Node 6LN: 6LoWPAN Node
6LR: 6LoWPAN Router 6LR: 6LoWPAN Router
6CIO: Capability Indication Option 6CIO: Capability Indication Option
EARO: (Extended) Address Registration Option -- (E)ARO ARO: Address Registration Option
EDAR: (Extended) Duplicate Address Request -- (E)DAR
EDAC: (Extended) Duplicate Address Confirmation -- (E)DAC DAC: Duplicate Address Confirmation
DAD: Duplicate Address Detection DAD: Duplicate Address Detection
DODAG: Destination-Oriented Directed Acyclic Graph DAR: Duplicate Address Request
IPv6 ND: IPv6 Neighbor Discovery EDAC: Extended Duplicate Address Confirmation
EDAR: Extended Duplicate Address Request
DODAG: Destination-Oriented Directed Acyclic Graph
LLN: Low-Power and Lossy Network LLN: Low-Power and Lossy Network
NA: Neighbor Advertisement NA: Neighbor Advertisement
NCE: Neighbor Cache Entry NCE: Neighbor Cache Entry
ND: Neighbor Discovery
NDP: Neighbor Discovery Protocol
NS: Neighbor Solicitation NS: Neighbor Solicitation
ROVR: Registration Ownership Verifier ROVR: Registration Ownership Verifier
RPL: IPv6 Routing Protocol for LLNs RPL: IPv6 Routing Protocol for LLNs
RA: Router Advertisement RA: Router Advertisement
RS: Router Solicitation RS: Router Solicitation
TID: Transaction ID
TID: Transaction ID (a sequence counter in the EARO)
2.4. References 2.4. References
In this document, readers will encounter terms and concepts that are In this document, readers will encounter terms and concepts that are
discussed in the following documents: discussed in the following documents:
o "Neighbor Discovery for IP version 6" [RFC4861], "IPv6 Stateless o "Neighbor Discovery for IP version 6" [RFC4861], "IPv6 Stateless
Address Autoconfiguration" [RFC4862] and "Optimistic Duplicate Address Autoconfiguration" [RFC4862] and "Optimistic Duplicate
Address Detection" [RFC4429], Address Detection" [RFC4429],
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o Neighbor Discovery Optimization for Low-Power and Lossy Networks o Neighbor Discovery Optimization for Low-Power and Lossy Networks
[RFC6775] and "Registration Extensions for 6LoWPAN Neighbor [RFC6775] and "Registration Extensions for 6LoWPAN Neighbor
Discovery" [RFC8505]. Discovery" [RFC8505].
3. Overview 3. Overview
Figure 1 illustrates backbone link federating a collection of LLNs as Figure 1 illustrates backbone link federating a collection of LLNs as
a single IPv6 Subnet, with a number of 6BBRs providing proxy-ND a single IPv6 Subnet, with a number of 6BBRs providing proxy-ND
services to their attached LLNs. services to their attached LLNs.
| |
+-----+ +-----+ +-----+ +-----+
| | Gateway (default) Router (default) | | (Optional) | | | | IPv6
| | Router | | 6LBR | | | | Node
+-----+ +-----+ +-----+ +-----+
| | Backbone side | |
| Backbone side ----+-------+-----------------+---+-------------+----+-----
+-------------------------+----------------------+
| | | | | |
+------+ +------+ +------+ +------+ +------+ +------+
| 6BBR | | 6BBR | | 6BBR | | 6BBR | | 6BBR | | 6BBR |
| | | | | | | | | | | |
+------+ +------+ +------+ +------+ +------+ +------+
o Wireless side o o o o o o Wireless side o o o o o
o o o o o o o o o o o o o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o
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form the subnet. form the subnet.
The 6BBRs use the Extended Address Registration Option (EARO) defined The 6BBRs use the Extended Address Registration Option (EARO) defined
in [RFC8505] as follows: in [RFC8505] as follows:
o The EARO is used in the IPv6 ND exchanges over the Backbone o The EARO is used in the IPv6 ND exchanges over the Backbone
between the 6BBRs to help distinguish duplication from movement. between the 6BBRs to help distinguish duplication from movement.
Extended Duplicate Address Messages (EDAR and EDAC) MAY also be Extended Duplicate Address Messages (EDAR and EDAC) MAY also be
used with a 6LBR, if one is present, and the 6BBR. Address used with a 6LBR, if one is present, and the 6BBR. Address
duplication is detected using the ROVR field. Conflicting duplication is detected using the ROVR field. Conflicting
registrations to different 6BBRs for the same 6LR address are registrations to different 6BBRs for the same Registered Address
resolved using the TID field. are resolved using the TID field.
o The Link Layer Address (LLA) that the 6BBR advertises for the o The Link Layer Address (LLA) that the 6BBR advertises for the
Registered Address on behalf of the Registered Node over the Registered Address on behalf of the Registered Node over the
Backbone can belong to the Registering Node; in that case, the Backbone can belong to the Registering Node; in that case, the
6BBR (acting as a Bridging Proxy (see Section 8)) bridges the 6BBR (acting as a Bridging Proxy (see Section 8)) bridges the
unicast packets. Alternatively, the LLA can be that of the 6BBR unicast packets. Alternatively, the LLA can be that of the 6BBR
on the Backbone interface, in which case the 6BBR (acting as a on the Backbone interface, in which case the 6BBR (acting as a
Routing Proxy(see Section 7)) receives the unicast packets at Routing Proxy(see Section 7)) receives the unicast packets at
Layer-2 and routes them. Layer-3 and routes over.
3.1. Updating RFC 6775 and RFC 8505 3.1. Updating RFC 6775 and RFC 8505
This specification adds the EARO as a possible option in RS, NS(DAD) This specification adds the EARO as a possible option in RS, NS(DAD)
and NA messages over the backbone. [RFC8505] requires that the and NA messages over the backbone. [RFC8505] requires that the
registration NS(EARO) contains an SLLAO. This specification details registration NS(EARO) contains an SLLAO. This specification details
the use of those messages over the backbone. the use of those messages over the backbone.
Note: [RFC6775] requires that the registration NS(EARO) contains an Note: [RFC6775] requires that the registration NS(EARO) contains an
SLLAO and [RFC4862] that the NS(DAD) is sent from the unspecified SLLAO and [RFC4862] that the NS(DAD) is sent from the unspecified
address for which there cannot be a SLLAO. Consequently, an NS(DAD) address for which there cannot be a SLLAO. Consequently, an NS(DAD)
cannot be confused with a registration. cannot be confused with a registration.
This specification adds the capability to insert IPv6 ND options in This specification adds the capability to insert IPv6 ND options in
the EDAR and EDAC messages. In particular, a 6BBR acting as a 6LR the EDAR and EDAC messages. In particular, a 6BBR acting as a 6LR
for the Registered Address can insert an SLLAO in the EDAR to the for the Registered Address can insert an SLLAO in the EDAR to the
6LBR in order to avoid a Lookup back. 6LBR in order to avoid a Lookup back. This enables the 6LBR to store
the MAC address associated to the Registered Address on a Link and to
serve as a mapping server as described in
[I-D.thubert-6lo-unicast-lookup].
3.2. Access Link 3.2. Access Link
Figure 2 illustrates a flow where 6LN forms an IPv6 Address and Figure 2 illustrates a flow where 6LN forms an IPv6 Address and
registers it to a 6BBR acting as a 6LR [RFC8505]. The 6BBRs applies registers it to a 6BBR acting as a 6LR [RFC8505]. The 6BBRs applies
ODAD (see Section 3.6) to the registered address to enable ODAD (see Section 3.6) to the registered address to enable
connectivity while the message flow is still in progress. In that connectivity while the message flow is still in progress. In that
example, a 6LBR is deployed on the backbone link to serve the whole example, a 6LBR is deployed on the backbone link to serve the whole
subnet, and EDAR / EDAC messages are used in combination with DAD to subnet, and EDAR / EDAC messages are used in combination with DAD to
enable coexistence with IPv6 ND over the backbone. enable coexistence with IPv6 ND over the backbone.
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| | | | | | | |
| 6LoWPAN ND |6LoWPAN ND | 6LoWPAN ND | IPv6 ND | 6LoWPAN ND |6LoWPAN ND | 6LoWPAN ND | IPv6 ND
| LLN link |Route-Over mesh|Ethernet/serial| Backbone | LLN link |Route-Over mesh|Ethernet/serial| Backbone
| | |/Internal call | | | |/Internal call |
| IPv6 ND RS | | | | IPv6 ND RS | | |
|-------------->| | | |-------------->| | |
|-----------> | | | |-----------> | | |
|------------------> | | |------------------> | |
| IPv6 ND RA | | | | IPv6 ND RA | | |
|<--------------| | | |<--------------| | |
| | <once> | | | | | |
| NS(EARO) | | | | NS(EARO) | | |
|-------------->| | | |-------------->| | |
| 6LoWPAN ND | Extended DAR | | | 6LoWPAN ND | Extended DAR | |
| |-------------->| | | |-------------->| |
| | | NS(EARO) | | | | NS(EARO) |
| | |-------------->| | | |-------------->|
| | | (proxied) | NS-DAD | | | (proxied) | NS-DAD
| | | |------> | | | |------>
| | | | (EARO) | | | | (EARO)
| | | | | | | |
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LLN, and is either collocated with or connected to the 6BBR over an LLN, and is either collocated with or connected to the 6BBR over an
IPv6 Link. IPv6 Link.
3.4. The Binding Table 3.4. The Binding Table
Addresses in a LLN that are reachable from the Backbone by way of the Addresses in a LLN that are reachable from the Backbone by way of the
6BBR function must be registered to that 6BBR, using an NS(EARO) with 6BBR function must be registered to that 6BBR, using an NS(EARO) with
the R flag set [RFC8505]. A 6BBR maintains a state for its active the R flag set [RFC8505]. A 6BBR maintains a state for its active
registrations in an abstract Binding Table. registrations in an abstract Binding Table.
An entry in the Binding Table Entry is called a "Binding". A Binding An entry in the Binding Table is called a "Binding". A Binding may
may be in Tentative, Reachable or Stale state. be in Tentative, Reachable or Stale state.
The 6BBR uses a combination of [RFC8505] and IPv6 ND over the The 6BBR uses a combination of [RFC8505] and IPv6 ND over the
Backbone to advertise the registration and avoid a duplication. Backbone to advertise the registration and avoid a duplication.
Conflicting registrations are solved by the 6BBRs transparently to Conflicting registrations are solved by the 6BBRs transparently to
the Registering Nodes. the Registering Nodes.
Only one 6LN may register a given Address, but the Address may be Only one 6LN may register a given Address, but the Address may be
registered to Multiple 6BBRs for higher availability. registered to Multiple 6BBRs for higher availability.
Over the LLN, Binding Table management is as follows: Over the LLN, Binding Table management is as follows:
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rejected with a status of 1 (Duplicate). rejected with a status of 1 (Duplicate).
3.5. Primary and Secondary 6BBRs 3.5. Primary and Secondary 6BBRs
A same address may be successfully registered to more than one 6BBR, A same address may be successfully registered to more than one 6BBR,
in which case the Registering Node uses the same EARO in all the in which case the Registering Node uses the same EARO in all the
parallel registrations. To allow for this, ND(DAD) and NA messages parallel registrations. To allow for this, ND(DAD) and NA messages
with an EARO that indicate an identical Binding in another 6BBR (same with an EARO that indicate an identical Binding in another 6BBR (same
Registered address, same TID, same ROVR) as silently ignored. Registered address, same TID, same ROVR) as silently ignored.
A 6BBR MAY be primary or secondary. The primary is the 6BBR that has A 6BBR MAY optionally be primary or secondary. The primary is the
the highest EUI-64 Address of all the 6BBRs that share a registration 6BBR that has the highest EUI-64 Address of all the 6BBRs that share
for the same Registered Address, with the same ROVR and same a registration for the same Registered Address, with the same ROVR
Transaction ID, the EUI-64 Address being considered as an unsigned and same Transaction ID, the EUI-64 Address being considered as an
64bit integer. A given 6BBR can be primary for a given Address and unsigned 64bit integer. A given 6BBR can be primary for a given
secondary for another Address, regardless of whether or not the Address and secondary for another Address, regardless of whether or
Addresses belong to the same 6LN. not the Addresses belong to the same 6LN.
In the following sections, is is expected that an NA is sent over the In the following sections, is is expected that an NA is sent over the
backbone only if the node is primary or does not support the concept backbone only if the node is primary or does not support the concept
of primary. More than one 6BBR claiming or defending an address of primary. More than one 6BBR claiming or defending an address
generates unwanted traffic but no reachability issue since all 6BBRs generates unwanted traffic but no reachability issue since all 6BBRs
provide reachability from the Backbone to the 6LN. provide reachability from the Backbone to the 6LN.
3.6. Using Optimistic DAD 3.6. Using Optimistic DAD
Optimistic Duplicate Address Detection [RFC4429] (ODAD) specifies how Optimistic Duplicate Address Detection [RFC4429] (ODAD) specifies how
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Perkins, C., McBride, M., Stanley, D., Kumari, W., and J. Perkins, C., McBride, M., Stanley, D., Kumari, W., and J.
Zuniga, "Multicast Considerations over IEEE 802 Wireless Zuniga, "Multicast Considerations over IEEE 802 Wireless
Media", draft-ietf-mboned-ieee802-mcast-problems-04 (work Media", draft-ietf-mboned-ieee802-mcast-problems-04 (work
in progress), November 2018. in progress), November 2018.
[I-D.nordmark-6man-dad-approaches] [I-D.nordmark-6man-dad-approaches]
Nordmark, E., "Possible approaches to make DAD more robust Nordmark, E., "Possible approaches to make DAD more robust
and/or efficient", draft-nordmark-6man-dad-approaches-02 and/or efficient", draft-nordmark-6man-dad-approaches-02
(work in progress), October 2015. (work in progress), October 2015.
[I-D.thubert-6lo-unicast-lookup]
Thubert, P. and E. Levy-Abegnoli, "IPv6 Neighbor Discovery
Unicast Lookup", draft-thubert-6lo-unicast-lookup-00 (work
in progress), January 2019.
[I-D.yourtchenko-6man-dad-issues] [I-D.yourtchenko-6man-dad-issues]
Yourtchenko, A. and E. Nordmark, "A survey of issues Yourtchenko, A. and E. Nordmark, "A survey of issues
related to IPv6 Duplicate Address Detection", draft- related to IPv6 Duplicate Address Detection", draft-
yourtchenko-6man-dad-issues-01 (work in progress), March yourtchenko-6man-dad-issues-01 (work in progress), March
2015. 2015.
[IEEEstd8021] [IEEEstd8021]
IEEE standard for Information Technology, "IEEE Standard IEEE standard for Information Technology, "IEEE Standard
for Information technology -- Telecommunications and for Information technology -- Telecommunications and
information exchange between systems Local and information exchange between systems Local and
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