--- 1/draft-ietf-6lo-rfc6775-update-09.txt 2017-10-13 06:13:11.495132739 -0700 +++ 2/draft-ietf-6lo-rfc6775-update-10.txt 2017-10-13 06:13:11.571134517 -0700 @@ -1,20 +1,23 @@ 6lo P. Thubert, Ed. Internet-Draft cisco Updates: 6775 (if approved) E. Nordmark Intended status: Standards Track -Expires: March 24, 2018 S. Chakrabarti - September 20, 2017 +Expires: April 16, 2018 S. Chakrabarti + + C. Perkins + Futurewei + October 13, 2017 An Update to 6LoWPAN ND - draft-ietf-6lo-rfc6775-update-09 + draft-ietf-6lo-rfc6775-update-10 Abstract This specification updates RFC 6775 - 6LoWPAN Neighbor Discovery, to clarify the role of the protocol as a registration technique, simplify the registration operation in 6LoWPAN routers, as well as to provide enhancements to the registration capabilities and mobility detection for different network topologies including the backbone routers performing proxy Neighbor Discovery in a low power network. @@ -26,21 +29,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on March 24, 2018. + This Internet-Draft will expire on April 16, 2018. Copyright Notice Copyright (c) 2017 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 @@ -51,215 +54,213 @@ described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Applicability of Address Registration Options . . . . . . . . 3 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Updating RFC 6775 . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Extended Address Registration Option (EARO) . . . . . . . 7 4.2. Transaction ID . . . . . . . . . . . . . . . . . . . . . 7 - 4.2.1. Comparing TID values . . . . . . . . . . . . . . . . 8 + 4.2.1. Comparing TID values . . . . . . . . . . . . . . . . 7 4.3. Owner Unique ID . . . . . . . . . . . . . . . . . . . . . 9 4.4. Extended Duplicate Address Messages . . . . . . . . . . . 10 4.5. Registering the Target Address . . . . . . . . . . . . . 10 4.6. Link-Local Addresses and Registration . . . . . . . . . . 11 - 4.7. Maintaining the Registration States . . . . . . . . . . . 13 + 4.7. Maintaining the Registration States . . . . . . . . . . . 12 5. Detecting Enhanced ARO Capability Support . . . . . . . . . . 14 - 6. Extended ND Options And Messages . . . . . . . . . . . . . . 15 - 6.1. Enhanced Address Registration Option (EARO) . . . . . . . 15 - 6.2. Extended Duplicate Address Message Formats . . . . . . . 18 + 6. Extended ND Options And Messages . . . . . . . . . . . . . . 14 + 6.1. Enhanced Address Registration Option (EARO) . . . . . . . 14 + 6.2. Extended Duplicate Address Message Formats . . . . . . . 17 6.3. New 6LoWPAN Capability Bits in the Capability Indication - Option . . . . . . . . . . . . . . . . . . . . . . . . . 19 - 7. Backward Compatibility . . . . . . . . . . . . . . . . . . . 19 - 7.1. Discovering the capabilities of an ND peer . . . . . . . 19 - 7.1.1. Using the "E" Flag in the 6CIO Option . . . . . . . . 19 - 7.1.2. Using the "T" Flag in the EARO . . . . . . . . . . . 20 - 7.2. Legacy 6LoWPAN Node . . . . . . . . . . . . . . . . . . . 21 - 7.3. Legacy 6LoWPAN Router . . . . . . . . . . . . . . . . . . 21 - 7.4. Legacy 6LoWPAN Border Router . . . . . . . . . . . . . . 22 - 8. Security Considerations . . . . . . . . . . . . . . . . . . . 22 - 9. Privacy Considerations . . . . . . . . . . . . . . . . . . . 23 - 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 - 10.1. ARO Flags . . . . . . . . . . . . . . . . . . . . . . . 24 - 10.2. ICMP Codes . . . . . . . . . . . . . . . . . . . . . . . 24 - 10.3. New ARO Status values . . . . . . . . . . . . . . . . . 25 - 10.4. New 6LoWPAN capability Bits . . . . . . . . . . . . . . 26 - 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 26 - 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 26 - 12.1. Normative References . . . . . . . . . . . . . . . . . . 26 - 12.2. Informative References . . . . . . . . . . . . . . . . . 27 - 12.3. External Informative References . . . . . . . . . . . . 30 + Option . . . . . . . . . . . . . . . . . . . . . . . . . 18 + 7. Backward Compatibility . . . . . . . . . . . . . . . . . . . 18 + 7.1. Discovering the capabilities of an ND peer . . . . . . . 18 + 7.1.1. Using the "E" Flag in the 6CIO . . . . . . . . . . . 19 + 7.1.2. Using the "T" Flag in the EARO . . . . . . . . . . . 19 + 7.2. Legacy 6LoWPAN Node . . . . . . . . . . . . . . . . . . . 20 + 7.3. Legacy 6LoWPAN Router . . . . . . . . . . . . . . . . . . 20 + 7.4. Legacy 6LoWPAN Border Router . . . . . . . . . . . . . . 21 + 8. Security Considerations . . . . . . . . . . . . . . . . . . . 21 + 9. Privacy Considerations . . . . . . . . . . . . . . . . . . . 22 + 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 + 10.1. ARO Flags . . . . . . . . . . . . . . . . . . . . . . . 23 + 10.2. ICMP Codes . . . . . . . . . . . . . . . . . . . . . . . 23 + 10.3. New ARO Status values . . . . . . . . . . . . . . . . . 24 + 10.4. New 6LoWPAN capability Bits . . . . . . . . . . . . . . 25 + 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25 + 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 + 12.1. Normative References . . . . . . . . . . . . . . . . . . 25 + 12.2. Informative References . . . . . . . . . . . . . . . . . 26 + 12.3. External Informative References . . . . . . . . . . . . 29 Appendix A. Applicability and Requirements Served . . . . . . . 30 - Appendix B. Requirements . . . . . . . . . . . . . . . . . . . . 31 - B.1. Requirements Related to Mobility . . . . . . . . . . . . 32 - B.2. Requirements Related to Routing Protocols . . . . . . . . 32 + Appendix B. Requirements . . . . . . . . . . . . . . . . . . . . 30 + B.1. Requirements Related to Mobility . . . . . . . . . . . . 31 + B.2. Requirements Related to Routing Protocols . . . . . . . . 31 B.3. Requirements Related to the Variety of Low-Power Link - types . . . . . . . . . . . . . . . . . . . . . . . . . . 33 - B.4. Requirements Related to Proxy Operations . . . . . . . . 34 - B.5. Requirements Related to Security . . . . . . . . . . . . 34 - B.6. Requirements Related to Scalability . . . . . . . . . . . 35 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36 + types . . . . . . . . . . . . . . . . . . . . . . . . . . 32 + B.4. Requirements Related to Proxy Operations . . . . . . . . 33 + B.5. Requirements Related to Security . . . . . . . . . . . . 33 + B.6. Requirements Related to Scalability . . . . . . . . . . . 34 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35 1. Introduction The scope of this draft is an IPv6 Low Power Networks including star and mesh topologies. This specification modifies and extends the behavior and protocol elements of "Neighbor Discovery Optimization for IPv6 over Low-Power Wireless Personal Area Networks" (6LoWPAN ND) - [RFC6775] to enable additional capabilities such as: + [RFC6775] to enable additional capabilities and enhancements such as: o Support for indicating mobility vs retry (T-bit) - o Ease up requirement of registration for link-local addresses + o Reduce requirement of registration for link-local addresses o Enhancement to Address Registration Option (ARO) - o Permitting registration of target address + o Permitting registration of a target address o Clarification of support of privacy and temporary addresses The applicability of 6LoWPAN ND registration is discussed in - Section 2, and new extensions and updates to RFC 6775 are presented + Section 2, and new extensions and updates to [RFC6775] are presented in Section 4. Considerations on Backward Compatibility, Security and Privacy are also elaborated upon in Section 7, Section 8 and in Section 9, respectively. 2. Applicability of Address Registration Options - The original purpose of the Address Registration Option (ARO) in the - original 6LoWPAN ND specification is to facilitate duplicate address - detection (DAD) for hosts as well as populate Neighbor Cache Entries - (NCE) [RFC4861] in the routers. This reduces the reliance on - multicast operations, which are often as intrusive as broadcast, in - IPv6 ND operations. + The purpose of the Address Registration Option (ARO) in the legacy + 6LoWPAN ND specification is to facilitate duplicate address detection + (DAD) for hosts as well as populate Neighbor Cache Entries (NCE) + [RFC4861] in the routers. This reduces the reliance on multicast + operations, which are often as intrusive as broadcast, in IPv6 ND + operations. - With this specification, a registration can fail or become useless - for reasons other than address duplication. Examples include: the - router having run out of space; a registration bearing a stale - sequence number perhaps denoting a movement of the host after the - registration was placed; a host misbehaving and attempting to + With this specification, a failed or useless registration can be + detected for reasons other than address duplication. Examples + include: the router having run out of space; a registration bearing a + stale sequence number perhaps denoting a movement of the host after + the registration was placed; a host misbehaving and attempting to register an invalid address such as the unspecified address + [RFC4291]; or a host using an address which is not topologically correct on that link. In such cases the host will receive an error to help diagnose the issue and may retry, possibly with a different address, and possibly registering to a different router, depending on the returned error. - However, the ability to return errors to address registrations is not - intended to be used to restrict the ability of hosts to form and use + The ability to return errors to address registrations is not intended + to be used to restrict the ability of hosts to form and use addresses, as recommended in "Host Address Availability Recommendations" [RFC7934]. In particular, the freedom to form and register addresses is needed - for enhanced privacy; each host may register a multiplicity of - address using mechanisms such as "Privacy Extensions for Stateless - Address Autoconfiguration (SLAAC) in IPv6" [RFC4941]. + for enhanced privacy; each host may register a number of addresses + using mechanisms such as "Privacy Extensions for Stateless Address + Autoconfiguration (SLAAC) in IPv6" [RFC4941]. - In the classical IPv6 ND [RFC4861], a router must have enough storage - to hold neighbor cache entries for all the addresses to which it may - forward. A router using the Address Registration mechanism needs - enough storage to hold NCEs for all the addresses that may be - registered to it, regardless of whether or not they are actively - communicating. For this reason, the number of registrations - supported by a 6LoWPAN Router (6LR) or 6LoWPAN Border Router (6LBR) - must be clearly documented. + In IPv6 ND [RFC4861], a router must have enough storage to hold + neighbor cache entries for all the addresses to which it may forward. + A router using the Address Registration mechanism also needs enough + storage to hold NCEs for all the addresses that may be registered to + it, regardless of whether or not they are actively communicating. + The number of registrations supported by a 6LoWPAN Router (6LR) or + 6LoWPAN Border Router (6LBR) must be clearly documented. - A network administrator should deploy adapted 6LR/6LBRs to support + A network administrator should deploy updated 6LR/6LBRs to support the number and type of devices in his network, based on the number of - IPv6 addresses that those devices require and their renewal rate and - behaviour. + IPv6 addresses that those devices require and their address renewal + rate and behaviour. 3. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this - document are to be interpreted as described in RFC 2119 [RFC2119]. + document are to be interpreted as described in [RFC2119]. Readers are expected to be familiar with all the terms and concepts that are discussed in o "Neighbor Discovery for IP version 6" [RFC4861], o "IPv6 Stateless Address Autoconfiguration" [RFC4862], o "IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs): Overview, Assumptions, Problem Statement, and Goals" [RFC4919], o "Neighbor Discovery Optimization for Low-power and Lossy Networks" [RFC6775] and o "Multi-link Subnet Support in IPv6" [I-D.ietf-ipv6-multilink-subnets], as well as the following terminology: - Backbone Link An IPv6 transit link that interconnects two or more - Backbone Routers. It is expected to be of a relatively high - speed compared to the LLN in order to support the trafic that - is required to federate multiple segments of the potentially - large LLN into a single IPv6 subnet. Also referred to as a to - as a Backbone, a LLN Backbone, and a Backbone Network. + Backbone Link: An IPv6 transit link that interconnects two or more + Backbone Routers. It is expected to be a higher speed device + speed compared to the LLN in order to carry the traffic that is + required to federate multiple segments of the potentially large + LLN into a single IPv6 subnet. - Backbone Router A logical network function in an IPv6 router that + Backbone Router: A logical network function in an IPv6 router that federates a LLN over a Backbone Link. In order to do so, the Backbone Router (6BBR) proxies the 6LoWPAN ND operations detailed in the document onto the matching operations that run - over the backbone, typically classical IPv6 ND. Note that 6BBR - is a logical function, just like 6LR and 6LBR, and that a same + over the backbone, typically IPv6 ND. Note that 6BBR is a + logical function, just like 6LR and 6LBR, and that a same physical router may operate all three. - Extended LLN The aggregation of multiple LLNs as defined in RFC 4919 + Extended LLN: The aggregation of multiple LLNs as defined in [RFC4919], interconnected by a Backbone Link via Backbone Routers, and forming a single IPv6 MultiLink Subnet. - Registration The process during which a wireless Node registers its + Registration: The process during which a 6LN registers its address(es) with the Border Router so the 6BBR can serve as proxy for ND operations over the Backbone. - Binding The association between an IP address with a MAC address, a + Binding: The association between an IP address with a MAC address, a port and/or other information about the node that owns the IP address. - Registered Node The node for which the registration is performed, + Registered Node: The node for which the registration is performed, and which owns the fields in the EARO option. - Registering Node The node that performs the registration to the + Registering Node: The node that performs the registration to the 6BBR, which may proxy for the registered node. - Registered Address An address owned by the Registered Node node that - was or is being registered. + Registered Address: An address owned by the Registered Node node + that was or is being registered. - legacy and original vs. updated In the context of this - specification, the terms "legacy" and "original" relate to the - support of the RFC 6775 by a 6LN, a 6LR or a 6LBR, whereas the - term "updated" refers to the support of this specification. + IPv6 ND: The IPv6 Neighbor Discovery protocol as specified in + [RFC4861] and [RFC4862]. - classical In the context of this specification, the term "classical" - relates to the support of the IPv6 Neighbor Discovery (IPv6 ND) - protocol as specified in RFC 4861 and RFC 4862. This - specification does not deprecate the classical IPv6 ND - Protocol. + legacy: a 6LN, a 6LR or a 6LBR that supports [RFC6775] but not this + specification. + + updated: a 6LN, a 6LR or a 6LBR that supports this specification. 4. Updating RFC 6775 This specification introduces the Extended Address Registration - Option (EARO) based on the ARO as defined in RFC 6775 [RFC6775]; in - particular a "T" flag is added that MUST be set is NS messages when - this specification is used, and echoed in NA messages to confirm that - the protocol is supported. + Option (EARO) based on the ARO as defined in [RFC6775]; in particular + a "T" flag is added that MUST be set in NS messages when this + specification is used, and echoed in NA messages to confirm that the + protocol is supported. - The extensions to the ARO option are reported to the Duplicate - Address Request (DAR) and Duplicate Address Confirmation (DAC) - messages, so as to convey the additional information all the way to - the 6LBR, and in turn the 6LBR may proxy the registration using - classical ND over a backbone as illustrated in Figure 1. + The extensions to the ARO option are used in the Duplicate Address + Request (DAR) and Duplicate Address Confirmation (DAC) messages, so + as to convey the additional information all the way to the 6LBR. In + turn the 6LBR may proxy the registration using IPv6 ND over a + backbone as illustrated in Figure 1. Note that this specification + avoids the extended DAR flow for Link Local Addresses in Route-Over + mode. 6LN 6LR 6LBR 6BBR | | | | | NS(EARO) | | | |--------------->| | | | | Extended DAR | | | |-------------->| | | | | | | | | proxy NS(EARO) | | | |--------------->| @@ -289,32 +290,29 @@ 4.1. Extended Address Registration Option (EARO) The Extended ARO (EARO) deprecates the ARO and is backward compatible with it. More details on backward compatibility can be found in Section 7. The semantics of the ARO are modified as follows: o The address that is being registered with a Neighbor Solicitation (NS) with an EARO is now the Target Address, as opposed to the - Source Address as specified in RFC 6775 [RFC6775] (see - Section 4.5). This change enables a 6LBR to use one of its - addresses as source to the proxy-registration of an address that - belongs to a LLN Node to a 6BBR. This also limits the use of an - address as source address before it is registered and the - associated DAD process is complete. + Source Address as specified in [RFC6775] (see Section 4.5). This + change enables a 6LBR to use one of its addresses as source to the + proxy-registration of an address that belongs to a LLN Node to a + 6BBR. This also limits the use of an address as source address + before it is registered and the associated DAD process is + complete. - o The Unique ID in the EARO Option is no longer required to be a MAC - address (see Section 4.3). This enables in particular the use of - a Provable Temporary UID (PT-UID) as opposed to burn-in MAC - address; the PT-UID provides an anchor trusted by the 6LR and 6LBR - to protect the state associated to the node. + o The Unique ID in the EARO Option is not required to be a MAC + address (see Section 4.3). o The specification introduces a Transaction ID (TID) field in the EARO (see Section 4.2). The TID MUST be provided by a node that supports this specification and a new "T" flag MUST be set to indicate so. o Finally, this specification introduces new status codes to help diagnose the cause of a registration failure (see Table 1). 4.2. Transaction ID @@ -418,211 +416,185 @@ 4.3. Owner Unique ID The Owner Unique ID (OUID) enables a duplicate address registration to be distinguished from a double registration or a movement. An ND message from the 6BBR over the Backbone that is proxied on behalf of a Registered Node must carry the most recent EARO option seen for that node. A NS/NA with an EARO and a NS/NA without a EARO thus represent different nodes; if they relate to a same target then an address duplication is likely. - With RFC 6775, the Owner Unique ID carries an EUI-64 burn-in address, - which implies that duplicate EUI-64 addresses are avoided. With this - specification, the Owner Unique ID is allowed to be extended to - different types of identifier, as long as the type is clearly - indicated. For instance, the type can be a cryptographic string and - used to prove the ownership of the registration as discussed in - "Address Protected Neighbor Discovery for Low-power and Lossy - Networks" [I-D.ietf-6lo-ap-nd]. + The Owner Unique ID in [RFC6775] is a EUI-64 preconfigured address, + under the assumption that duplicate EUI-64 addresses are avoided. + With this specification, the Owner Unique ID is allowed to be + extended to different types of identifier, as long as the type is + clearly indicated. For instance, the type can be a cryptographic + string and used to prove the ownership of the registration as + discussed in "Address Protected Neighbor Discovery for Low-power and + Lossy Networks" [I-D.ietf-6lo-ap-nd]. - In any fashion, it is recommended that the node stores the unique Id - or the keys used to generate that ID in persistent memory. - Otherwise, it will be prevented to re-register a same address after a - reboot that would cause a loss of memory until the 6LBR times out the - registration. + The node SHOULD store the unique ID, or a way to generate that ID, in + persistent memory. Otherwise, if a reboot causes a loss of memory, + re-registering the same address could be impossible until the 6LBR + times out the previous registration. 4.4. Extended Duplicate Address Messages In order to map the new EARO content in the DAR/DAC messages, a new TID field is added to the Extended DAR (EDAR) and the Extended DAC (EDAC) messages as a replacement to a Reserved field, and an odd value of the ICMP Code indicates support for the TID, to transport the "T" flag. - In order to prepare for new extensions, and though no option had been - earlier defined for the Duplicate Address messages, implementations + In order to prepare for future extensions, and though no option has + been defined for the Duplicate Address messages, implementations SHOULD expect ND options after the main body, and SHOULD ignore them. As for the EARO, the Extended Duplicate Address messages are backward - compatible with the original versions, and remarks concerning - backwards compatibility between the 6LN and the 6LR apply similarly - between a 6LR and a 6LBR. + compatible with the legacy versions, and remarks concerning backwards + compatibility for the protocol between the 6LN and the 6LR apply + similarly between a 6LR and a 6LBR. 4.5. Registering the Target Address The Registering Node is the node that performs the registration to - the 6BBR. As inherited from RFC 6775, it may be the Registered Node - as well, in which case it registers one of its own addresses, and - indicates its own MAC Address as Source Link Layer Address (SLLA) in - the NS(EARO). + the 6BBR. As in [RFC6775], it may be the Registered Node as well, in + which case it registers one of its own addresses, and indicates its + own MAC Address as Source Link Layer Address (SLLA) in the NS(EARO). This specification adds the capability to proxy the registration operation on behalf of a Registered Node that is reachable over a LLN mesh. In that case, if the Registered Node is reachable from the 6BBR over a Mesh-Under mesh, the Registering Node indicates the MAC Address of the Registered Node as SLLA in the NS(EARO). If the Registered Node is reachable over a Route-Over mesh from the Registering Node, the SLLA in the NS(ARO) is that of the Registering Node. This enables the Registering Node to attract the packets from the 6BBR and route them over the LLN to the Registered Node . In order to enable the latter operation, this specification changes the behavior of the 6LN and the 6LR so that the Registered Address is found in the Target Address field of the NS and NA messages as - opposed to the Source Address. - - The reason for this change is to enable proxy-registrations on behalf - of other nodes, for instance to enable a RPL root to register - addresses on behalf of other LLN nodes, as discussed in Appendix B.4. - In that case, the Registering Node MUST indicate its own address as - source of the ND message and its MAC address in the Source Link-Layer - Address Option (SLLAO), since it still expects to receive and route - the packets. Since the Registered Address belongs to the Registered - Node, that address is indicated in the Target Address field of the NS - message. - - With this convention, a TLLA option indicates the link-layer address - of the 6LN that owns the address, whereas the SLLA Option in a NS - message indicates that of the Registering Node, which can be the - owner device, or a proxy. + opposed to the Source Address. With this convention, a TLLA option + indicates the link-layer address of the 6LN that owns the address, + whereas the SLLA Option in a NS message indicates that of the + Registering Node, which can be the owner device, or a proxy. The Registering Node is reachable from the 6LR, and is also the one expecting packets for the 6LN. Therefore, it MUST place its own Link Layer Address in the SLLA Option that MUST always be placed in a - registration NS(EARO) message. This maintains compatibility with the - original 6LoWPAN ND [RFC6775]. + registration NS(EARO) message. This maintains compatibility with + legacy 6LoWPAN ND [RFC6775]. 4.6. Link-Local Addresses and Registration Considering that LLN nodes are often not wired and may move, there is no guarantee that a Link-Local address stays unique between a potentially variable and unbounded set of neighboring nodes. - Compared to RFC 6775, this specification only requires that a Link- - Local address is unique from the perspective of the nodes that use it - to communicate (e.g. the 6LN and the 6LR in an NS/NA exchange). This - simplifies the DAD process for Link-Local addresses, and there is no - exchange of Duplicate Address messages between the 6LR and a 6LBR for - Link-Local addresses. - - According to RFC 6775, a 6LoWPAN Node (6LN) uses the an address being - registered as the source of the registration message. This generates - complexities in the 6LR to be able to cope with a potential - duplication, in particular for global addresses. - - To simplify this, a 6LN and a 6LR that conform this specification - MUST always use Link-Local addresses as source and destination - addresses for the registration NS/NA exchange. As a result, the - registration is globally faster, and some of the complexity is - removed. + Compared to [RFC6775], this specification only requires that a Link- + Local address is unique from the perspective of the two nodes that + use it to communicate (e.g. the 6LN and the 6LR in an NS/NA + exchange). This simplifies the DAD process in Route-Over Mode for + Link-Local addresses, and there is no exchange of Duplicate Address + messages between the 6LR and a 6LBR for Link-Local addresses. In more details: An exchange between two nodes using Link-Local addresses implies that they are reachable over one hop and that at least one of the 2 nodes acts as a 6LR. A node MUST register a Link-Local address to a 6LR in order to obtain reachability from that 6LR beyond the current exchange, and in particular to use the Link-Local address as source address to register other addresses, e.g. global addresses. If there is no collision with an address previously registered to - this 6LR by another 6LN, then, from the standpoint of this 6LR, this - Link-Local address is unique and the registration is acceptable. - Conversely, it may possibly happen that two different 6LRs expose the - same Link-Local address but different link-layer addresses. In that - case, a 6LN may only interact with one of the 6LRs so as to avoid - confusion in the 6LN neighbor cache. + this 6LR by another 6LN, then the Link-Local address is unique from + the standpoint of this 6LR and the registration is acceptable. + Alternatively, two different 6LRs might expose the same Link-Local + address but different link-layer addresses. In that case, a 6LN MUST + only interact with one of the 6LRs. The DAD process between the 6LR and a 6LBR, which is based on an exchange of Duplicate Address messages, does not need to take place for Link-Local addresses. - It is desired that a 6LR does not need to modify its state associated - to the Source Address of an NS(EARO) message. For that reason, when - possible, it is RECOMMENDED to use an address that is already - registered with a 6LR + It is preferable for a 6LR to avoid modifying its state associated to + the Source Address of an NS(EARO) message. For that reason, when + possible, an address that is already registered with a 6LR SHOULD be + used by a 6LN. When registering to a 6LR that conforms this specification, a node MUST use a Link-Local address as the source address of the registration, whatever the type of IPv6 address that is being registered. That Link-Local Address MUST be either already registered, or the address that is being registered. When a Registering Node does not have an already-Registered Address, it MUST register a Link-Local address, using it as both the Source and the Target Address of an NS(EARO) message. In that case, it is RECOMMENDED to use a Link-Local address that is (expected to be) - globally unique, e.g. derived from a burn-in MAC address. An EARO - option in the response NA indicates that the 6LR supports this - specification. + globally unique, e.g., derived from a globally unique hardware MAC + address. An EARO option in the response NA indicates that the 6LR + supports this specification. Since there is no Duplicate Address exchange for Link-Local addresses, the 6LR may answer immediately to the registration of a Link-Local address, based solely on its existing state and the Source Link-Layer Option that MUST be placed in the NS(EARO) message as - required in RFC 6775 [RFC6775]. + required in [RFC6775]. A node needs to register its IPv6 Global Unicast IPv6 Addresses (GUAs) to a 6LR in order to establish global reachability for these - addresses via that 6LR. When registering with a 6LR that conforms - this specification, a Registering Node does not use its GUA as Source - Address, in contrast to a node that complies to RFC 6775 [RFC6775]. - For non-Link-Local addresses, the Duplicate Address exchange MUST - conform to RFC 6775, but the extended formats described in this - specification for the DAR and the DAC are used to relay the extended - information in the case of an EARO. + addresses via that 6LR. When registering with an updated 6LR, a + Registering Node does not use its GUA as Source Address, in contrast + to a node that complies to [RFC6775]. For non-Link-Local addresses, + the Duplicate Address exchange MUST conform to [RFC6775], but the + extended formats described in this specification for the DAR and the + DAC are used to relay the extended information in the case of an + EARO. 4.7. Maintaining the Registration States This section discusses protocol actions that involve the Registering Node, the 6LR and the 6LBR. It must be noted that the portion that deals with a 6LBR only applies to those addresses that are registered - to it, which, as discussed in Section 4.6, is not the case for Link- + to it; as discussed in Section 4.6, this is not the case for Link- Local addresses. The registration state includes all data that is stored in the router relative to that registration, in particular, but not limited to, an NCE in a 6LR. 6LBRs and 6BBRs may store additional registration information in more complex data structures and use protocols that are out of scope of this document to keep them synchonized when they are distributed. When its Neighbor Cache is full, a 6LR cannot accept a new registration. In that situation, the EARO is returned in a NA message with a Status of 2, and the Registering Node may attempt to register to another 6LR. - Conversely the registry in the 6LBR may be saturated, in which case - the LBR cannot guarantee that a new address is effectively not a - duplicate. In that case, the 6LBR replies to a EDAR message with a - EDAC message that carries a Status code 9 indicating "6LBR Registry - saturated", and the address stays in TENTATIVE state. Note: this - code is used by 6LBRs instead of Status 2 when responding to a - Duplicate Address message exchange and passed on to the Registering - Node by the 6LR. There is no point for the node to retry this - registration immediately via another 6LR, since the problem is global - to the network. The node may either abandon that address, deregister - other addresses first to make room, or keep the address in TENTATIVE - state and retry later. + If the registry in the 6LBR is be saturated, in which case the LBR + cannot guarantee that a new address is effectively not a duplicate. + In that case, the 6LBR replies to a EDAR message with a EDAC message + that carries a Status code 9 indicating "6LBR Registry saturated", + and the address stays in TENTATIVE state. Note: this code is used by + 6LBRs instead of Status 2 when responding to a Duplicate Address + message exchange and passed on to the Registering Node by the 6LR. + There is no point for the node to retry this registration immediately + via another 6LR, since the problem is global to the network. The + node may either abandon that address, deregister other addresses + first to make room, or keep the address in TENTATIVE state and retry + later. - A node renews an existing registration by repeatedly sending NS(EARO) - messages for the Registered Address. In order to refresh the - registration state in the 6LBR, these registrations MUST be reported - to the 6LBR. + A node renews an existing registration by sending a new NS(EARO) + message for the Registered Address. In order to refresh the + registration state in the 6LBR, the registration MUST be reported to + the 6LBR. A node that ceases to use an address SHOULD attempt to deregister that address from all the 6LRs to which it has registered the address, which is achieved using an NS(EARO) message with a Registration Lifetime of 0. A node that moves away from a particular 6LR SHOULD attempt to deregister all of its addresses registered to that 6LR and register to a new 6LR with an incremented TID. When/if the node shows up elsewhere, an asynchronous NA(EARO) or EDAC message with a status of @@ -635,83 +607,76 @@ clean up its state. Upon receiving a NS(EARO) message with a Registration Lifetime of 0 and determining that this EARO is the freshest for a given NCE (see Section 4.2), a 6LR cleans up its NCE. If the address was registered to the 6LBR, then the 6LR MUST report to the 6LBR, through a Duplicate Address exchange with the 6LBR, or an alternate protocol, indicating the null Registration Lifetime and the latest TID that this 6LR is aware of. - Upon the Extended DAR message, the 6LBR evaluates if this is the - freshest TID it has received for that particular registry entry. If - it is, then the entry is scheduled to be removed, and the EDAR is - answered with a EDAC message bearing a Status of 0 "Success". If it - is not the freshest, then a Status 3 "Moved" is returned instead, and - the existing entry is conserved. - - Upon timing out a registration, a 6LR removes silently its binding - cache entry, and a 6LBR schedules its entry to be removed. + Upon receiving the Extended DAR message, the 6LBR evaluates if this + is the most recent TID it has received for that particular registry + entry. If so, then the entry is scheduled to be removed, and the + EDAR is answered with a EDAC message bearing a Status of 0 + ("Success"). Otherwise, a Status 3 ("Moved") is returned instead, + and the existing entry is maintained. When an address is scheduled to be removed, the 6LBR SHOULD keep its entry in a DELAY state for a configurable period of time, so as to protect a mobile node that deregistered from one 6LR and did not register yet to a new one, or the new registration did not reach yet the 6LBR due to propagation delays in the network. Once the DELAY time is passed, the 6LBR removes silently its entry. 5. Detecting Enhanced ARO Capability Support The "Generic Header Compression for IPv6 over 6LoWPANs" [RFC7400] introduces the 6LoWPAN Capability Indication Option (6CIO) to indicate a node's capabilities to its peers. This specification - extends the format defined in RFC 7400 to signal the support for - EARO, as well as the node's capability to act as a 6LR, 6LBR and - 6BBR. + extends the format defined in [RFC7400] to signal support for EARO, + as well as the node's capability to act as a 6LR, 6LBR and 6BBR. - With RFC 7400, the 6CIO is typically sent in a Router Solicitation - (RS) message. When used to signal the capabilities above per this - specification, the 6CIO is typically present in Router Advertisement - (RA) messages but can also be present in RS, Neighbor Solicitation - (NS) and Neighbor Advertisement (NA) messages. + The 6CIO is typically sent in a Router Solicitation (RS) message. + When used to signal capabilities per this specification, the 6CIO is + typically present in Router Advertisement (RA) messages but can also + be present in RS, Neighbor Solicitation (NS) and Neighbor + Advertisement (NA) messages. 6. Extended ND Options And Messages This specification does not introduce new options, but it modifies existing ones and updates the associated behaviors as specified in the following subsections. 6.1. Enhanced Address Registration Option (EARO) The Address Registration Option (ARO) is defined in section 4.1. of [RFC6775]. - The Enhanced Address Registration Option (EARO) is intended to be - used as a replacement to the ARO option within Neighbor Discovery NS - and NA messages between a 6LN and its 6LR. Conversely, the Extended - Duplicate Address messages, EDAR and EDAC, are to be used in - replacement of the DAR and DAC messages so as to transport the new - information between 6LRs and 6LBRs across LLNs meshes such as 6TiSCH - networks. + The Enhanced Address Registration Option (EARO) updates the ARO + option within Neighbor Discovery NS and NA messages between a 6LN and + its 6LR. On the other hand, the Extended Duplicate Address messages, + EDAR and EDAC, replace the DAR and DAC messages so as to transport + the new information between 6LRs and 6LBRs across LLNs meshes such as + 6TiSCH networks. An NS message with an EARO option is a registration if and only if it also carries an SLLAO option. The EARO option also used in NS and NA messages between Backbone Routers over the Backbone link to sort out the distributed registration state; in that case, it does not carry the SLLAO option and is not confused with a registration. When using the EARO option, the address being registered is found in - the Target Address field of the NS and NA messages. This differs - from 6LoWPAN ND RFC 6775 [RFC6775] which specifies that the address - being registered is the source of the NS. + the Target Address field of the NS and NA messages. - The EARO extends the ARO and is recognized by the "T" flag set. The + The EARO extends the ARO and is indicated by the "T" flag set. The format of the EARO option is as follows: 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 |T| TID | Registration Lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | @@ -728,24 +693,24 @@ Length: 8-bit unsigned integer. The length of the option in units of 8 bytes. Always 2. Status: 8-bit unsigned integer. Indicates the status of a registration in the NA response. MUST be set to 0 in NS messages. See Table 1 below. +-------+-----------------------------------------------------------+ | Value | Description | +-------+-----------------------------------------------------------+ - | 0..2 | See RFC 6775 [RFC6775]. Note: a Status of 1 "Duplicate | - | | Address" applies to the Registered Address. If the Source | - | | Address conflicts with an existing registration, | - | | "Duplicate Source Address" should be used. | + | 0..2 | See [RFC6775]. Note: a Status of 1 "Duplicate Address" | + | | applies to the Registered Address. If the Source Address | + | | conflicts with an existing registration, "Duplicate | + | | Source Address" should be used. | | | | | 3 | Moved: The registration fails because it is not the | | | freshest. This Status indicates that the registration is | | | rejected because another more recent registration was | | | done, as indicated by a same OUI and a more recent TID. | | | One possible cause is a stale registration that has | | | progressed slowly in the network and was passed by a more | | | recent one. It could also indicate a OUI collision. | | | | | 4 | Removed: The binding state was removed. This may be | @@ -798,21 +763,21 @@ associated state should be removed. Owner Unique Identifier (OUI): A globally unique identifier for the node associated. This can be the EUI-64 derived IID of an interface, or some provable ID obtained cryptographically. 6.2. Extended Duplicate Address Message Formats The Duplicate Address Request (DAR) and the Duplicate Address - Confirmation (DAC) messages are defined in section 4.4. of [RFC6775]. + Confirmation (DAC) messages are defined in section 4.4 of [RFC6775]. Those messages follow a common base format, which enables information from the ARO to be transported over multiple hops. The Duplicate Address Messages are extended to adapt to the Extended ARO format, as follows: 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 | @@ -843,31 +808,31 @@ TID: 1-byte integer; same definition and processing as the TID in the EARO option as defined in Section 6.1. Owner Unique Identifier (OUI): 8 bytes; same definition and processing as the OUI in the EARO option as defined in Section 6.1. 6.3. New 6LoWPAN Capability Bits in the Capability Indication Option - This specification defines a number of capability bits in the 6CIO - that was introduced by RFC 7400 for use in IPv6 ND RA messages. + This specification defines new capability bits for use in the 6CIO, + which was introduced by [RFC7400] for use in IPv6 ND RA messages. Routers that support this specification SHOULD set the "E" flag and 6LN SHOULD favor 6LR routers that support this specification over those that do not. Routers that are capable of acting as 6LR, 6LBR and 6BBR SHOULD set the "L", "B" and "P" flags, respectively. In - particular, the function 6LR is usually collocated with that of 6LBR. + particular, the function 6LR is often collocated with that of 6LBR. Those flags are not mutually exclusive and if a router is capable of - running multiple functions, it SHOULD set all the related flags. + performing multiple functions, it SHOULD set all the related flags. 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 = 1 | Reserved |L|B|P|E|G| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: New capability Bits L, B, P, E in the 6CIO @@ -880,105 +845,99 @@ B: Node is a 6LBR. P: Node is a 6BBR, proxying for nodes on this link. E: This specification is supported and applied. 7. Backward Compatibility 7.1. Discovering the capabilities of an ND peer - -7.1.1. Using the "E" Flag in the 6CIO Option +7.1.1. Using the "E" Flag in the 6CIO If the 6CIO is used in an ND message and the sending node supports this specification, then the "E" Flag MUST be set. A router that supports this specification SHOULD indicate that with a - 6CIO Option, but this might not be practical if the link-layer MTU is - too small. + 6CIO. - If the Registering Node (RN) receives a CIO in a Router Advertisement - message, then the setting of the "E" Flag indicates whether or not - this specification is supported. RN SHOULD favor a router that - supports this specification over those that do not. + If the Registering Node (RN) receives a 6CIO in a Router + Advertisement message, then the setting of the "E" Flag indicates + whether or not this specification is supported. 7.1.2. Using the "T" Flag in the EARO One alternate way for a 6LN to discover the router's capabilities to first register a Link Local address, placing the same address in the Source and Target Address fields of the NS message, and setting the "T" Flag. The node may for instance register an address that is based on EUI-64. For such address, DAD is not required and using the SLLAO option in the NS is actually more consistent with existing ND specifications such as the "Optimistic Duplicate Address Detection (DAD) for IPv6" [RFC4429]. - Once that first registration is complete, the node knows from the + Once its first registration is complete, the node knows from the setting of the "T" Flag in the response whether the router supports this specification. If support is verified, the node may register other addresses that it owns, or proxy-register addresses on behalf some another node, indicating those addresses being registered in the Target Address field of the NS messages, while using one of its own previously registered addresses as source. A node that supports this specification MUST always use an EARO as a replacement to an ARO in its registration to a router. This is - harmless since the "T" flag and TID field are reserved in RFC 6775 - are ignored by a legacy router. A router that supports this + harmless since the "T" flag and TID field are reserved in [RFC6775], + and are ignored by a legacy router. A router that supports this specification answers an ARO with an ARO and answers an EARO with an EARO. This specification changes the behavior of the peers in a registration flows. To enable backward compatibility, a 6LB that registers to a 6LR that is not known to support this specification - MUST behave in a manner that is compatible with RFC 6775. A 6LN can + MUST behave in a manner that is compatible with [RFC6775]. A 6LN can achieve that by sending a NS(EARO) message with a Link-Local Address used as both Source and Target Address, as described in Section 4.6. Once the 6LR is known to support this specification, the 6LN MUST obey this specification. 7.2. Legacy 6LoWPAN Node A legacy 6LN will use the Registered Address as source and will not use an EARO option. An updated 6LR MUST accept that registration if - it is valid per RFC 6775, and it MUST manage the binding cache - accordingly. The updated 6LR MUST then use the original Duplicate - Address messages as specified in RFC 6775 to indicate to the 6LBR + it is valid per [RFC6775], and it MUST manage the binding cache + accordingly. The updated 6LR MUST then use the legacy Duplicate + Address messages as specified in [RFC6775] to indicate to the 6LBR that the TID is not present in the messages. - The main difference with RFC 6775 is that Duplicate Address exchange + The main difference with [RFC6775] is that Duplicate Address exchange for DAD is avoided for Link-Local addresses. In any case, the 6LR SHOULD use an EARO in the reply, and may use any of the Status codes defined in this specification. 7.3. Legacy 6LoWPAN Router The first registration by an updated 6LN MUST be for a Link-Local address, using that Link-Local address as source. A legacy 6LR will - not make a difference and accept -or reject- that registration as if - the 6LN was a legacy node. + not make a difference and treat that registration as if the 6LN was a + legacy node. An updated 6LN will always use an EARO option in the registration NS message, whereas a legacy 6LR will always reply with an ARO option in - the NA message. So from that first registration, the updated 6LN can - figure whether the 6LR supports this specification or not. + the NA message. From that first registration, the updated 6LN can + determine whether or not the 6LR supports this specification. After detecting a legacy 6LR, an updated 6LN may attempt to find an - alternate 6LR that is updated. In order to be backward compatible, - after detecting that a 6LR is legacy, the 6LN MUST adhere to RFC 6775 - in future protocol exchanges with that 6LR, and source the packet - with the Registered Address. + alternate 6LR that is updated. - Note that the updated 6LN SHOULD use an EARO in the request - regardless of the type of 6LR, legacy or updated, which implies that - the "T" flag is set. + An updated 6LN SHOULD use an EARO in the request regardless of the + type of 6LR, legacy or updated, which implies that the "T" flag is + set. If an updated 6LN moves from an updated 6LR to a legacy 6LR, the legacy 6LR will send a legacy DAR message, which can not be compared with an updated one for freshness. Allowing legacy DAR messages to replace a state established by the updated protocol in the 6LBR would be an attack vector and that cannot be the default behavior. But if legacy and updated 6LRs coexist temporarily in a network, then @@ -988,29 +947,29 @@ 7.4. Legacy 6LoWPAN Border Router With this specification, the Duplicate Address messages are extended to transport the EARO information. Similarly to the NS/NA exchange, updated 6LBR devices always use the Extended Duplicate Address messages and all the associated behavior so they can amlways be differentiated from legacy ones. Note that a legacy 6LBR will accept and process an EDAR message as if - it was an original one, so the original support of DAD is preserved. + it was a legacy DAR, so legacy support of DAD is preserved. 8. Security Considerations - This specification extends RFC 6775 [RFC6775], and the security - section of that draft also applies to this as well. In particular, - it is expected that the link layer is sufficiently protected to - prevent a rogue access, either by means of physical or IP security on - the Backbone Link and link layer cryptography on the LLN. + This specification extends [RFC6775], and the security section of + that draft also applies to this as well. In particular, it is + expected that the link layer is sufficiently protected to prevent a + rogue access, either by means of physical or IP security on the + Backbone Link and link layer cryptography on the LLN. This specification also expects that the LLN MAC provides secure unicast to/from the Backbone Router and secure Broadcast from the Backbone Router in a way that prevents tempering with or replaying the RA messages. This specification recommends to using privacy techniques (see Section 9, and protection against address theft such as provided by "Address Protected Neighbor Discovery for Low-power and Lossy Networks" [I-D.ietf-6lo-ap-nd], which guarantees the ownership of the @@ -1020,52 +979,52 @@ 6LR or the 6LBR with a Denial-of-Service attack against the registry. It may also happen that the registry of a 6LR or a 6LBR is saturated and cannot take any more registration, which effectively denies the requesting a node the capability to use a new address. In order to alleviate those concerns, Section 4.7 provides a number of recommendations that ensure that a stale registration is removed as soon as possible from the 6LR and 6LBR. In particular, this specification recommends that: o A node that ceases to use an address SHOULD attempt to deregister - that address from all the 6LRs to which it is registered. The - flow is propagated to the 6LBR when needed, and a sequence number - is used to make sure that only the freshest command is acted upon. + that address from all the 6LRs to which it is registered. See + Section 4.2 for the mechanism to avoid replay attacks and avoiding + the use of stale registration information. o The Registration lifetimes SHOULD be individually configurable for each address or group of addresses. The nodes SHOULD be configured with a Registration Lifetime that reflects their expectation of how long they will use the address with the 6LR to which it is registered. In particular, use cases that involve mobility or rapid address changes SHOULD use lifetimes that are larger yet of a same order as the duration of the expectation of presence. o The router (6LR or 6LBR) SHOULD be configurable so as to limit the number of addresses that can be registered by a single node, as identified at least by MAC address and preferably by security credentials. When that maximum is reached, the router should use - a Least-Recently-Used (LRU) logic so as to clean up the addresses - that were not used for the longest time, keeping at least one - Link-Local address, and attempting to keep one or more stable - addresses if such can be recognized, e.g. from the way the IID is - formed or because they are used over a much longer time span than - other (privacy, shorter-lived) addresses. The address lifetimes - SHOULD be individually configurable. + a Least-Recently-Used (LRU) algorithm to clean up the addresses, + keeping at least one Link-Local address. The router SHOULD + attempt to keep one or more stable addresses if stability can be + determined, e.g. from the way the IID is formed or because they + are used over a much longer time span than other (privacy, + shorter-lived) addresses. Address lifetimes SHOULD be + individually configurable. o In order to avoid denial of registration for the lack of - resources, administrators SHOULD take great care to deploy + resources, administrators should take great care to deploy adequate numbers of 6LRs to cover the needs of the nodes in their range, so as to avoid a situation of starving nodes. It is expected that the 6LBR that serves a LLN is a more capable node then the average 6LR, but in a network condition where it may - become saturated, a particular deployment SHOULD distribute the + become saturated, a particular deployment should distribute the 6LBR functionality, for instance by leveraging a high speed Backbone and Backbone Routers to aggregate multiple LLNs into a larger subnet. The LLN nodes depend on the 6LBR and the 6BBR for their operation. A trust model must be put in place to ensure that the right devices are acting in these roles, so as to avoid threats such as black-holing, or bombing attack whereby an impersonated 6LBR would destroy state in the network by using the "Removed" Status code. @@ -1101,111 +1060,109 @@ IANA is requested to create a new subregistry for "ARO Flags". This specification defines 8 positions, bit 0 to bit 7, and assigns bit 7 for the "T" flag in Section 6.1. The policy is "IETF Review" or "IESG Approval" [RFC8126]. The initial content of the registry is as shown in Table 2. New subregistry for ARO Flags under the "Internet Control Message Protocol version 6 (ICMPv6) [RFC4443] Parameters" - +------------+--------------+-----------+ + +-------------+--------------+-----------+ | ARO Status | Description | Document | - +------------+--------------+-----------+ + +-------------+--------------+-----------+ | 0..6 | Unassigned | | - | 7 | "T" Flag | RFC This | - +------------+--------------+-----------+ + | 7 | "T" Flag | This RFC | + +-------------+--------------+-----------+ Table 2: new ARO Flags 10.2. ICMP Codes IANA is requested to create a new entry in the ICMPv6 "Code" Fields subregistry of the Internet Control Message Protocol version 6 (ICMPv6) Parameters for the ICMP codes related to the ICMP type 157 and 158 Duplicate Address Request (shown in Table 3) and Confirmation (shown in Table 4), respectively, as follows: New entries for ICMP types 157 DAR message - +------+----------------------+------------+ + +-------+----------------------+------------+ | Code | Name | Reference | - +------+----------------------+------------+ + +-------+----------------------+------------+ | 0 | Original DAR message | RFC 6775 | - | 1 | Extended DAR message | RFC This | - +------+----------------------+------------+ + | 1 | Extended DAR message | This RFC | + +-------+----------------------+------------+ Table 3: new ICMPv6 Code Fields New entries for ICMP types 158 DAC message - +------+----------------------+------------+ + +-------+----------------------+------------+ | Code | Name | Reference | - +------+----------------------+------------+ + +-------+----------------------+------------+ | 0 | Original DAC message | RFC 6775 | - | 1 | Extended DAC message | RFC This | - +------+----------------------+------------+ + | 1 | Extended DAC message | This RFC | + +-------+----------------------+------------+ Table 4: new ICMPv6 Code Fields 10.3. New ARO Status values IANA is requested to make additions to the Address Registration Option Status Values Registry as follows: Address Registration Option Status Values Registry - +------------+------------------------------------------+-----------+ + +-------------+-----------------------------------------+-----------+ | ARO Status | Description | Document | - +------------+------------------------------------------+-----------+ - | 3 | Moved | RFC This | - | 4 | Removed | RFC This | - | 5 | Validation Requested | RFC This | - | 6 | Duplicate Source Address | RFC This | - | 7 | Invalid Source Address | RFC This | - | 8 | Registered Address topologically | RFC This | + +-------------+-----------------------------------------+-----------+ + | 3 | Moved | This RFC | + | 4 | Removed | This RFC | + | 5 | Validation Requested | This RFC | + | 6 | Duplicate Source Address | This RFC | + | 7 | Invalid Source Address | This RFC | + | 8 | Registered Address topologically | This RFC | | | incorrect | | - | 9 | 6LBR registry saturated | RFC This | - | 10 | Validation Failed | RFC This | - +------------+------------------------------------------+-----------+ + | 9 | 6LBR registry saturated | This RFC | + | 10 | Validation Failed | This RFC | + +-------------+-----------------------------------------+-----------+ Table 5: New ARO Status values 10.4. New 6LoWPAN capability Bits IANA is requested to make additions to the Subregistry for "6LoWPAN capability Bits" as follows: Subregistry for "6LoWPAN capability Bits" under the "Internet Control Message Protocol version 6 (ICMPv6) Parameters" - +----------------+----------------------+-----------+ - | capability Bit | Description | Document | - +----------------+----------------------+-----------+ - | 11 | 6LR capable (L bit) | RFC This | - | 12 | 6LBR capable (B bit) | RFC This | - | 13 | 6BBR capable (P bit) | RFC This | - | 14 | EARO support (E bit) | RFC This | - +----------------+----------------------+-----------+ + +-----------------+----------------------+-----------+ + | Capability Bit | Description | Document | + +-----------------+----------------------+-----------+ + | 11 | 6LR capable (L bit) | This RFC | + | 12 | 6LBR capable (B bit) | This RFC | + | 13 | 6BBR capable (P bit) | This RFC | + | 14 | EARO support (E bit) | This RFC | + +-----------------+----------------------+-----------+ Table 6: New 6LoWPAN capability Bits 11. Acknowledgments Kudos to Eric Levy-Abegnoli who designed the First Hop Security - infrastructure upon which the first backbone router was implemented; - many thanks to Charlie Perkins for his in-depth reviews and - constructive suggestions, as well as to Sedat Gormus, Rahul Jadhav - and Lorenzo Colitti for their various contributions and reviews. - Also many thanks to Thomas Watteyne for his early implementation of a - 6LN that was instrumental to the early tests of the 6LR, 6LBR and - Backbone Router. + infrastructure upon which the first backbone router was implemented. + Many thanks to Sedat Gormus, Rahul Jadhav and Lorenzo Colitti for + their various contributions and reviews. Also many thanks to Thomas + Watteyne for his early implementation of a 6LN that was instrumental + to the early tests of the 6LR, 6LBR and Backbone Router. 12. References 12.1. 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, . @@ -1259,22 +1216,22 @@ 6man-efficient-nd-07 (work in progress), February 2015. [I-D.delcarpio-6lo-wlanah] Vega, L., Robles, I., and R. Morabito, "IPv6 over 802.11ah", draft-delcarpio-6lo-wlanah-01 (work in progress), October 2015. [I-D.ietf-6lo-ap-nd] Sarikaya, B., Thubert, P., and M. Sethi, "Address Protected Neighbor Discovery for Low-power and Lossy - Networks", draft-ietf-6lo-ap-nd-02 (work in progress), May - 2017. + Networks", draft-ietf-6lo-ap-nd-03 (work in progress), + September 2017. [I-D.ietf-6lo-backbone-router] Thubert, P., "IPv6 Backbone Router", draft-ietf-6lo- backbone-router-04 (work in progress), July 2017. [I-D.ietf-6lo-nfc] Choi, Y., Hong, Y., Youn, J., Kim, D., and J. Choi, "Transmission of IPv6 Packets over Near Field Communication", draft-ietf-6lo-nfc-07 (work in progress), June 2017. @@ -1383,21 +1340,22 @@ [RFC8163] Lynn, K., Ed., Martocci, J., Neilson, C., and S. Donaldson, "Transmission of IPv6 over Master-Slave/Token- Passing (MS/TP) Networks", RFC 8163, DOI 10.17487/RFC8163, May 2017, . 12.3. External Informative References [IEEEstd802154] IEEE, "IEEE Standard for Low-Rate Wireless Networks", - IEEE Standard 802.15.4, DOI 10.1109/IEEESTD.2016.7460875, + IEEE Standard 802.15.4, DOI 10.1109/IEEE + P802.15.4-REVd/D01, June 2017, . [Perlman83] Perlman, R., "Fault-Tolerant Broadcast of Routing Information", North-Holland Computer Networks 7: 395-405, 1983, . Appendix A. Applicability and Requirements Served @@ -1413,37 +1371,37 @@ connect to the Internet via a RPL mesh Network, but this requires additions to the 6LOWPAN ND protocol to support mobility and reachability in a secured and manageable environment. This specification details the new operations that are required to implement the 6TiSCH architecture and serves the requirements listed in Appendix B.2. The term LLN is used loosely in this specification to cover multiple types of WLANs and WPANs, including Low-Power Wi-Fi, BLUETOOTH(R) Low Energy, IEEE Std.802.11AH and IEEE Std.802.15.4 wireless meshes, so - as to address the requirements discussed in Appendix B.3 + as to address the requirements discussed in Appendix B.3. This specification can be used by any wireless node to associate at Layer-3 with a 6BBR and register its IPv6 addresses to obtain routing services including proxy-ND operations over the Backbone, effectively providing a solution to the requirements expressed in Appendix B.4. "Efficiency aware IPv6 Neighbor Discovery Optimizations" [I-D.chakrabarti-nordmark-6man-efficient-nd] suggests that 6LoWPAN ND [RFC6775] can be extended to other types of links beyond IEEE Std. 802.15.4 for which it was defined. The registration technique is beneficial when the Link-Layer technique used to carry IPv6 multicast packets is not sufficiently efficient in terms of delivery ratio or energy consumption in the end devices, in particular to enable energy-constrained sleeping nodes. The value of such extension is especially apparent in the case of mobile wireless nodes, to reduce - the multicast operations that are related to classical ND ([RFC4861], + the multicast operations that are related to IPv6 ND ([RFC4861], [RFC4862]) and plague the wireless medium. This serves scalability requirements listed in Appendix B.6. Appendix B. Requirements This section lists requirements that were discussed at 6lo for an update to 6LoWPAN ND. This specification meets most of them, but those listed in Appendix B.5 which are deferred to a different specification such as [I-D.ietf-6lo-ap-nd], and those related to multicast. @@ -1480,35 +1438,35 @@ characteristics. It is required that a 6LoWPAN Node attached via ND to a 6LR would need to participate in the selected routing protocol to obtain reachability via the 6LR. Next to the 6LBR unicast address registered by ND, other addresses including multicast addresses are needed as well. For example a routing protocol often uses a multicast address to register changes to established paths. ND needs to register such a multicast address to enable routing concurrently with discovery. - Multicast is needed for groups. Groups MAY be formed by device type + Multicast is needed for groups. Groups may be formed by device type (e.g. routers, street lamps), location (Geography, RPL sub-tree), or both. The Bit Index Explicit Replication (BIER) Architecture [I-D.ietf-bier-architecture] proposes an optimized technique to enable multicast in a LLN with a very limited requirement for routing state in the nodes. Related requirements are: - Req2.1: The ND registration method SHOULD be extended in such a - fashion that the 6LR MAY advertise the Address of a 6LoWPAN Node over - the selected routing protocol and obtain reachability to that Address - using the selected routing protocol. + Req2.1: The ND registration method SHOULD be extended so that the 6LR + is able to advertise the Address of a 6LoWPAN Node over the selected + routing protocol and obtain reachability to that Address using the + selected routing protocol. Req2.2: Considering RPL, the Address Registration Option that is used in the ND registration SHOULD be extended to carry enough information to generate a DAO message as specified in [RFC6550] section 6.4, in particular the capability to compute a Path Sequence and, as an option, a RPLInstanceID. Req2.3: Multicast operations SHOULD be supported and optimized, for instance using BIER or MPL. Whether ND is appropriate for the registration to the 6BBR is to be defined, considering the additional @@ -1544,23 +1502,23 @@ Req3.3: The Address Registration Option used in the ND registration SHOULD be extended to carry the relevant forms of unique Identifier. Req3.4: The Neighbour Discovery should specify the formation of a site-local address that follows the security recommendations from [RFC7217]. B.4. Requirements Related to Proxy Operations Duty-cycled devices may not be able to answer themselves to a lookup - from a node that uses classical ND on a Backbone and may need a - proxy. Additionally, the duty-cycled device may need to rely on the - 6LBR to perform registration to the 6BBR. + from a node that uses IPv6 ND on a Backbone and may need a proxy. + Additionally, the duty-cycled device may need to rely on the 6LBR to + perform registration to the 6BBR. The ND registration method SHOULD defend the addresses of duty-cycled devices that are sleeping most of the time and not capable to defend their own Addresses. Related requirements are: Req4.1: The registration mechanism SHOULD enable a third party to proxy register an Address on behalf of a 6LoWPAN node that may be sleeping or located deeper in an LLN mesh. @@ -1574,21 +1532,21 @@ B.5. Requirements Related to Security In order to guarantee the operations of the 6LoWPAN ND flows, the spoofing of the 6LR, 6LBR and 6BBRs roles should be avoided. Once a node successfully registers an address, 6LoWPAN ND should provide energy-efficient means for the 6LBR to protect that ownership even when the node that registered the address is sleeping. In particular, the 6LR and the 6LBR then should be able to verify - whether a subsequent registration for a given Address comes from the + whether a subsequent registration for a given address comes from the original node. In a LLN it makes sense to base security on layer-2 security. During bootstrap of the LLN, nodes join the network after authorization by a Joining Assistant (JA) or a Commissioning Tool (CT). After joining nodes communicate with each other via secured links. The keys for the layer-2 security are distributed by the JA/CT. The JA/CT can be part of the LLN or be outside the LLN. In both cases it is needed that packets are routed between JA/CT and the joining node. @@ -1664,10 +1622,18 @@ Santa Clara, CA USA Email: nordmark@sonic.net Samita Chakrabarti San Jose, CA USA Email: samitac.ietf@gmail.com + + Charles E. Perkins + Futurewei + 2330 Central Expressway + Santa Clara 95050 + Unites States + + Email: charliep@computer.org