--- 1/draft-ietf-ipwave-ipv6-over-80211ocb-47.txt 2019-07-06 09:13:14.621856346 -0700 +++ 2/draft-ietf-ipwave-ipv6-over-80211ocb-48.txt 2019-07-06 09:13:14.689858048 -0700 @@ -1,49 +1,50 @@ IPWAVE Working Group N. Benamar Internet-Draft Moulay Ismail University Intended status: Standards Track J. Haerri -Expires: December 29, 2019 Eurecom +Expires: January 7, 2020 Eurecom J. Lee Sangmyung University T. Ernst YoGoKo - June 27, 2019 + July 6, 2019 - Basic support for IPv6 over IEEE Std 802.11 Networks operating Outside + Basic Support for IPv6 over IEEE Std 802.11 Networks Operating Outside the Context of a Basic Service Set (IPv6-over-80211-OCB) - draft-ietf-ipwave-ipv6-over-80211ocb-47 + draft-ietf-ipwave-ipv6-over-80211ocb-48 Abstract This document provides methods and settings, and describes limitations, for using IPv6 to communicate among nodes in range of - one another over a single IEEE 802.11-OCB link with minimal change to - existing stacks. Optimizations and usage of IPv6 over more complex - scenarios is not covered and is subject of future work. + one another over a single IEEE 802.11-OCB link. This support does + only require minimal changes to existing stacks. Optimizations and + usage of IPv6 over more complex scenarios is not covered in this + specification and is subject of future work. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. 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 December 29, 2019. + This Internet-Draft will expire on January 7, 2020. Copyright Notice Copyright (c) 2019 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 @@ -90,309 +91,311 @@ G.2. Capture in Normal Mode . . . . . . . . . . . . . . . . . 27 Appendix H. Extra Terminology . . . . . . . . . . . . . . . . . 29 Appendix I. Neighbor Discovery (ND) Potential Issues in Wireless Links . . . . . . . . . . . . . . . . . . . . . . . 30 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32 1. Introduction This document provides a baseline with limitations for using IPv6 to communicate among nodes in range of one another over a single IEEE - 802.11-OCB link [IEEE-802.11-2016] (a.k.a "802.11p" see Appendix A, - Appendix B and Appendix C) with minimal change to existing stacks. - This document describes the layering of IPv6 networking on top of the - IEEE Std 802.11 MAC layer or an IEEE Std 802.3 MAC layer with a frame - translation underneath. The resulting stack inherits from IPv6 over - Ethernet [RFC 2464] and operates over 802.11-OCB providing at least - P2P connectivity using IPv6 ND and link-local addresses. ND - Extensions and IPWAVE optimizations for vehicular communications are - not in scope. The expectation is that further specs will elaborate - for more complex vehicular networking scenarios. + 802.11-OCB link [IEEE-802.11-2016] (a.k.a., "802.11p" see Appendicies + Appendix A, Appendix B and Appendix C) with minimal changes to + existing stacks. Moreover, the document identifies limitations of + such usage. Concretly, the document describes the layering of IPv6 + networking on top of the IEEE Std 802.11 MAC layer or an IEEE Std + 802.3 MAC layer with a frame translation underneath. The resulting + stack inherits from IPv6 over Ethernet [RFC 2464], but operates over + 802.11-OCB to provide at least P2P (Point to Point) connectivity + using IPv6 ND and link-local addresses. The IPv6 network layer operates on 802.11-OCB in the same manner as - operating on Ethernet, but there are two kinds of exceptions: + operating on Ethernet with following exceptions: o Exceptions due to different operation of IPv6 network layer on 802.11 than on Ethernet. The operation of IP on Ethernet is described in [RFC1042], [RFC2464] . o Exceptions due to the OCB nature of 802.11-OCB compared to 802.11. This has impacts on security, privacy, subnet structure and - movement detection. For security and privacy recommendations see - Section 5 and Section 4.4. The subnet structure is described in - Section 4.6. The movement detection on OCB links is not described - in this document. + movement detection. Security and privacy recommendations are + discussed in Section 5 and Section 4.4. The subnet structure is + described in Section 4.6. The movement detection on OCB links is + not described in this document. Likewise, ND Extensions and + IPWAVE optimizations for vehicular communications are not in + scope. The expectation is that further specifications will be + edited to cover more complex vehicular networking scenarios. - In the published literature, many documents describe aspects and - problems related to running IPv6 over 802.11-OCB: - [I-D.ietf-ipwave-vehicular-networking]. + The reader may refer to [I-D.ietf-ipwave-vehicular-networking] for an + overview of problems related to running IPv6 over 802.11-OCB. It is + out of scope of this document to reiterate those. 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 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. - IP-OBU (Internet Protocol On-Board Unit): an IP-OBU is a computer - situated in a vehicle such as an automobile, bicycle, or similar. It - has at least one IP interface that runs in mode OCB of 802.11, and - that has an "OBU" transceiver. See the definition of the term "OBU" - in section Appendix H. + The document makes uses of the following terms: IP-OBU (Internet + Protocol On-Board Unit): an IP-OBU denotes a computer situated in a + vehicle such as a car, bicycle, or similar. It has at least one IP + interface that runs in mode OCB of 802.11, and that has an "OBU" + transceiver. See the definition of the term "OBU" in section + Appendix H. IP-RSU (IP Road-Side Unit): an IP-RSU is situated along the road. It - has at least two distinct IP-enabled interfaces; the wireless PHY/MAC - layer of at least one of its IP-enabled interfaces is configured to - operate in 802.11-OCB mode. An IP-RSU communicates with the IP-OBU - in the vehicle over 802.11 wireless link operating in OCB mode. An - IP-RSU is similar to an Access Network Router (ANR) defined in + has at least two distinct IP-enabled interfaces. The wireless PHY/ + MAC layer of at least one of its IP-enabled interfaces is configured + to operate in 802.11-OCB mode. An IP-RSU communicates with the IP- + OBU in the vehicle over 802.11 wireless link operating in OCB mode. + An IP-RSU is similar to an Access Network Router (ANR) defined in [RFC3753], and a Wireless Termination Point (WTP) defined in [RFC5415]. - OCB (outside the context of a basic service set - BSS): A mode of + OCB (outside the context of a basic service set - BSS): is a mode of operation in which a STA is not a member of a BSS and does not utilize IEEE Std 802.11 authentication, association, or data confidentiality. - 802.11-OCB: mode specified in IEEE Std 802.11-2016 when the MIB - attribute dot11OCBActivited is true. Note: compliance with standards - and regulations set in different countries when using the 5.9GHz - frequency band is required. + 802.11-OCB: refers to the mode specified in IEEE Std 802.11-2016 when + the MIB attribute dot11OCBActivited is 'true'. Note: compliance with + standards and regulations set in different countries when using the + 5.9GHz frequency band is required. 3. Communication Scenarios where IEEE 802.11-OCB Links are Used - The IEEE 802.11-OCB Networks are used for vehicular communications, + The IEEE 802.11-OCB networks are used for vehicular communications, as 'Wireless Access in Vehicular Environments'. In particular, we refer the reader to [I-D.ietf-ipwave-vehicular-networking], that lists some scenarios and requirements for IP in Intelligent - Transportation Systems. + Transportation Systems (ITS). The link model is the following: STA --- 802.11-OCB --- STA. In vehicular networks, STAs can be IP-RSUs and/or IP-OBUs. All links are assumed to be P2P and multiple links can be on one radio interface. While 802.11-OCB is clearly specified, and a legacy IPv6 stack can operate on such links, the use of the operating environment (vehicular networks) brings in new perspectives. 4. IPv6 over 802.11-OCB 4.1. Maximum Transmission Unit (MTU) The default MTU for IP packets on 802.11-OCB is inherited from - RFC2464 and is 1500 octets. This value of the MTU respects the - recommendation that every link on the Internet must have a minimum - MTU of 1280 octets (stated in [RFC8200], and the recommendations - therein, especially with respect to fragmentation). + RFC2464 and is, as such, 1500 octets. This value of the MTU respects + the recommendation that every link on the Internet must have a + minimum MTU of 1280 octets (stated in [RFC8200], and the + recommendations therein, especially with respect to fragmentation). 4.2. Frame Format IP packets MUST be transmitted over 802.11-OCB media as QoS Data frames whose format is specified in IEEE 802.11 spec [IEEE-802.11-2016]. The IPv6 packet transmitted on 802.11-OCB are immediately preceded by a Logical Link Control (LLC) header and an 802.11 header. In the LLC header, and in accordance with the EtherType Protocol Discrimination (EPD, see Appendix D), the value of the Type field MUST be set to 0x86DD (IPv6). The mapping to the 802.11 data service MUST use a 'priority' value of 1, which specifies the use of QoS with a 'Background' user priority. To simplify the Application Programming Interface (API) between the operating system and the 802.11-OCB media, device drivers MAY - implement IPv6 over Ethernet per RFC 2464 and then a frame + implement IPv6-over-Ethernet as per RFC 2464 and then a frame translation from 802.3 to 802.11 in order to minimize the code changes. 4.3. Link-Local Addresses There are several types of IPv6 addresses [RFC4291], [RFC4193], that - MAY be assigned to an 802.11-OCB interface. Among these types of - addresses only the IPv6 link-local addresses MAY be formed using an + may be assigned to an 802.11-OCB interface. Among these types of + addresses only the IPv6 link-local addresses can be formed using an EUI-64 identifier, in particular during transition time. If the IPv6 link-local address is formed using an EUI-64 identifier, then the mechanism of forming that address is the same mechanism as used to form an IPv6 link-local address on Ethernet links. Moreover, whether or not the interface identifier is derived from the EUI-64 A identifier, its length is 64 bits as is the case for Ethernet [RFC2464]. 4.4. Stateless Autoconfiguration The steps a host takes in deciding how to autoconfigure its - interfaces in IP version 6 are described in [RFC4862]. This section - describes the formation of Interface Identifiers for IPv6 addresses - of type 'Global' or 'Unique Local'. For Interface Identifiers for - IPv6 address of type 'Link-Local' see Section 4.3. + interfaces in IP6 are described in [RFC4862]. This section describes + the formation of Interface Identifiers for IPv6 addresses of type + 'Global' or 'Unique Local'. For Interface Identifiers for IPv6 + address of type 'Link-Local' are discussed in Section 4.3. The RECOMMENDED method for forming stable Interface Identifiers (IIDs) is described in [RFC8064]. The method of forming IIDs - described in section 4 of [RFC2464] MAY be used during transition + described in Section 4 of [RFC2464] MAY be used during transition time, in particular for IPv6 link-local addresses. Regardless of how - to form the Interface Identifier, its length is 64 bits, as is the - case of the IPv6 over Ethernet specification [RFC2464]. + to form the IID, its length is 64 bits, as is the case of the IPv6 + over Ethernet [RFC2464]. - The bits in the Interface Identifier have no generic meaning and the - identifier should be treated as an opaque value. The bits - 'Universal' and 'Group' in the identifier of an 802.11-OCB interface - are significant, as this is an IEEE link-layer address. The details - of this significance are described in [RFC7136]. + The bits in the IID have no specific meaning and the identifier + should be treated as an opaque value. The bits 'Universal' and + 'Group' in the identifier of an 802.11-OCB interface are significant, + as this is an IEEE link-layer address. The details of this + significance are described in [RFC7136]. - Semantically opaque Interface Identifiers, instead of meaningful - Interface Identifiers derived from a valid and meaningful MAC address - ([RFC2464], section 4), help avoid certain privacy risks (see the - risks mentioned in Section 5.1.1). If semantically opaque Interface - Identifiers are needed, they MAY be generated using the method for - generating semantically opaque Interface Identifiers with IPv6 - Stateless Address Autoconfiguration given in [RFC7217]. Typically, - an opaque Interface Identifier is formed starting from identifiers - different than the MAC addresses, and from cryptographically strong - material. Thus, privacy sensitive information is absent from - Interface IDs, because it is impossible to calculate back the initial - value from which the Interface ID was first generated (intuitively, - it is as hard as mentally finding the square root of a number, and as - impossible as trying to use computers to identify quickly whether a - large number is prime). + Semantically opaque IIDs, instead of meaningful IIs derived from a + valid and meaningful MAC address ([RFC2464], Section 4), help avoid + certain privacy risks (see the risks mentioned in Section 5.1.1). If + semantically opaque IIDs are needed, they MAY be generated using the + method for generating semantically opaque IIDs with IPv6 Stateless + Address Autoconfiguration given in [RFC7217]. Typically, an opaque + IID is formed starting from identifiers different than the MAC + addresses, and from cryptographically strong material. Thus, privacy + sensitive information is absent from Interface IDs, because it is + impossible to calculate back the initial value from which the + Interface ID was first generated. Some applications that use IPv6 packets on 802.11-OCB links (among - other link types) may benefit from IPv6 addresses whose Interface - Identifiers don't change too often. It is RECOMMENDED to use the - mechanisms described in RFC 7217 to permit the use of Stable - Interface Identifiers that do not change within one subnet prefix. A - possible source for the Net-Iface Parameter is a virtual interface - name, or logical interface name, that is decided by a local - administrator. + other link types) may benefit from IPv6 addresses whose IIDs don't + change too often. It is RECOMMENDED to use the mechanisms described + in RFC 7217 to permit the use of Stable IIDs that do not change + within one subnet prefix. A possible source for the Net-Iface + Parameter is a virtual interface name, or logical interface name, + that is decided by a local administrator. 4.5. Address Mapping Unicast and multicast address mapping MUST follow the procedures - specified for Ethernet interfaces in sections 6 and 7 of [RFC2464]. + specified for Ethernet interfaces specified in Sections 6 and 7 of + [RFC2464]. 4.5.1. Address Mapping -- Unicast - This draft is scoped for AR and DAD per RFC 4861 [RFC4861]. + This document is scoped for Address Resolution (AR) and Duplicate + Address Detection (DAD) per RFC 4861 [RFC4861]. 4.5.2. Address Mapping -- Multicast The multicast address mapping is performed according to the method specified in section 7 of [RFC2464]. The meaning of the value "3333" mentioned in that section 7 of [RFC2464] is defined in section 2.3.1 of [RFC7042]. Transmitting IPv6 packets to multicast destinations over 802.11 links proved to have some performance issues [I-D.ietf-mboned-ieee802-mcast-problems]. These issues may be - exacerbated in OCB mode.A Future improvement to this specification - SHOULD consider solutions for these problems. + exacerbated in OCB mode.A A future improvement to this specification + should consider solutions for these problems. 4.6. Subnet Structure A subnet may be formed over 802.11-OCB interfaces of vehicles that are in close range (not by their in-vehicle interfaces). A Prefix - List conceptual data structure ([RFC4861] section 5.1) is maintained + List conceptual data structure ([RFC4861] Section 5.1) is maintained for each 802.11-OCB interface. An IPv6 subnet on which Neighbor Discovery protocol (ND) can be - mapped on an OCB network iff all nodes share a single broadcast + mapped on an OCB network if all nodes share a single broadcast Domain, which is generally the case for P2P OCB links; The extension to IPv6 ND operating on a subnet that covers multiple OCB links and not fully overlapping (NBMA) is not in scope. The structure of this subnet is ephemeral, in that it is strongly influenced by the mobility of vehicles: the hidden terminal effects appear; the 802.11 networks in OCB mode may be considered as 'ad-hoc' networks with an addressing model as described in [RFC5889]. On - another hand, the structure of the internal subnets in each car is - relatively stable. + another hand, the structure of the internal subnets in each vehicle + is relatively stable. As recommended in [RFC5889], when the timing requirements are very strict (e.g. fast drive through IP-RSU coverage), no on-link subnet prefix should be configured on an 802.11-OCB interface. In such cases, the exclusive use of IPv6 link-local addresses is RECOMMENDED. Additionally, even if the timing requirements are not very strict - (e.g. the moving subnet formed by two following vehicles is stable, a - fixed IP-RSU is absent), the subnet is disconnected from the Internet - (a default route is absent), and the addressing peers are equally - qualified (impossible to determine that some vehicle owns and - distributes addresses to others) the use of link-local addresses is - RECOMMENDED. + (e.g., the moving subnet formed by two following vehicles is stable, + a fixed IP-RSU is absent), the subnet is disconnected from the + Internet (i.e., a default route is absent), and the addressing peers + are equally qualified (that is, it is impossible to determine that + some vehicle owns and distributes addresses to others) the use of + link-local addresses is RECOMMENDED. - The baseline Neighbor Discovery protocol (ND) [RFC4861] MUST be - supported over 802.11-OCB links. Transmitting ND packets may prove - to have some performance issues see Section 4.5.2, and Appendix I. - These issues may be exacerbated in OCB mode. Solutions for these - problems SHOULD consider the OCB mode of operation. Future solutions - to OCB should consider solutions for avoiding broadcast. The best of - current knowledge indicates the kinds of issues that may arise with - ND in OCB mode; they are described in Appendix I. + The baseline ND protocol [RFC4861] MUST be supported over 802.11-OCB + links. Transmitting ND packets may prove to have some performance + issues as mentioned in Section 4.5.2, and Appendix I. These issues + may be exacerbated in OCB mode. Solutions for these problems should + consider the OCB mode of operation. Future solutions to OCB should + consider solutions for avoiding broadcast. The best of current + knowledge indicates the kinds of issues that may arise with ND in OCB + mode; they are described in Appendix I. Protocols like Mobile IPv6 [RFC6275] , [RFC3963] and DNAv6 [RFC6059], - which depend on timely movement detection, might need additional + which depend on a timely movement detection, might need additional tuning work to handle the lack of link-layer notifications during handover. This is for further study. 5. Security Considerations Any security mechanism at the IP layer or above that may be carried out for the general case of IPv6 may also be carried out for IPv6 operating over 802.11-OCB. The OCB operation is stripped off of all existing 802.11 link-layer security mechanisms. There is no encryption applied below the - network layer running on 802.11-OCB. At application layer, the IEEE - 1609.2 document [IEEE-1609.2] does provide security services for + network layer running on 802.11-OCB. At the application layer, the + IEEE 1609.2 document [IEEE-1609.2] provides security services for certain applications to use; application-layer mechanisms are out-of- scope of this document. On another hand, a security mechanism provided at networking layer, such as IPsec [RFC4301], may provide data security protection to a wider range of applications. 802.11-OCB does not provide any cryptographic protection, because it operates outside the context of a BSS (no Association Request/ Response, no Challenge messages). Any attacker can therefore just sit in the near range of vehicles, sniff the network (just set the - interface card's frequency to the proper range) and perform attacks + interface card's frequency to the proper range) and performs attacks without needing to physically break any wall. Such a link is less protected than commonly used links (wired link or protected 802.11). The potential attack vectors are: MAC address spoofing, IP address and session hijacking, and privacy violation Section 5.1. A previous - work at SAVI WG presents some threats [RFC6959], while SeND presented - in [RFC3971] and [RFC3972] is a solution against address theft but it - is complex and not deployed. + work at SAVI WG identifies some threats [RFC6959], while SeND + presented in [RFC3971] and [RFC3972] is a solution against address + theft but it is complex and not deployed. More IETF protocols are available in the toolbox of the IP security - protocol designer. Certain ETSI protocols related to security - protocols in Intelligent Transportation Systems are described in - [ETSI-sec-archi]. + protocol designer. Some ETSI protocols related to security protocols + in ITS are described in [ETSI-sec-archi]. 5.1. Privacy Considerations As with all Ethernet and 802.11 interface identifiers ([RFC7721]), the identifier of an 802.11-OCB interface may involve privacy, MAC - address spoofing and IP address hijacking risks. A vehicle embarking - an IP-OBU whose egress interface is 802.11-OCB may expose itself to + address spoofing and IP hijacking risks. A vehicle embarking an IP- + OBU whose egress interface is 802.11-OCB may expose itself to eavesdropping and subsequent correlation of data; this may reveal data considered private by the vehicle owner; there is a risk of being tracked. In outdoors public environments, where vehicles typically circulate, the privacy risks are more important than in indoors settings. It is highly likely that attacker sniffers are deployed along routes which listen for IEEE frames, including IP packets, of vehicles passing by. For this reason, in the 802.11-OCB deployments, there is a strong necessity to use protection tools such as dynamically changing MAC addresses Section 5.2, semantically opaque Interface Identifiers and stable Interface Identifiers Section 4.4. An example of change policy is to change the MAC - address of the OCB interface each time the system boots upThis may - help mitigate privacy risks to a certain level. + address of the OCB interface each time the system boots up. This may + help mitigate privacy risks to a certain level. Futhermore, for + pricavy concerns ([RFC8065]) recommends using an address generation + scheme rather than addresses generated from a fixed link-layer + address. 5.1.1. Privacy Risks of Meaningful info in Interface IDs The privacy risks of using MAC addresses displayed in Interface Identifiers are important. The IPv6 packets can be captured easily in the Internet and on-link in public roads. For this reason, an attacker may realize many attacks on privacy. One such attack on 802.11-OCB is to capture, store and correlate Company ID information present in MAC addresses of many cars (e.g. listen for Router Advertisements, or other IPv6 application data packets, and record @@ -641,20 +644,24 @@ [RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy Considerations for IPv6 Address Generation Mechanisms", RFC 7721, DOI 10.17487/RFC7721, March 2016, . [RFC8064] Gont, F., Cooper, A., Thaler, D., and W. Liu, "Recommendation on Stable IPv6 Interface Identifiers", RFC 8064, DOI 10.17487/RFC8064, February 2017, . + [RFC8065] Thaler, D., "Privacy Considerations for IPv6 Adaptation- + Layer Mechanisms", RFC 8065, DOI 10.17487/RFC8065, + February 2017, . + [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, July 2017, . 9.2. Informative References @@ -1011,21 +1018,21 @@ +-+-+-{ PHY_SAP }+-+-+-+-+-+-+-| | | | PLME | | | PHY Layer | PLME_SAP | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: EtherType Protocol Discrimination Appendix E. Design Considerations The networks defined by 802.11-OCB are in many ways similar to other - networks of the 802.11 family. In theory, the encapsulation of IPv6 + networks of the 802.11 family. In theory, the transportation of IPv6 over 802.11-OCB could be very similar to the operation of IPv6 over other networks of the 802.11 family. However, the high mobility, strong link asymmetry and very short connection makes the 802.11-OCB link significantly different from other 802.11 networks. Also, the automotive applications have specific requirements for reliability, security and privacy, which further add to the particularity of the 802.11-OCB link. Appendix F. IEEE 802.11 Messages Transmitted in OCB mode