Network Working Group D. Eastlake 3rd Request for Comments: 5342 Eastlake Enterprises BCP: 141 September 2008 Updates: 2153 Category: Best Current Practice IANA Considerations and IETF Protocol Usage for IEEE 802 Parameters Status of This Memo This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Distribution of this memo is unlimited.
AbstractSome IETF protocols make use of Ethernet frame formats and IEEE 802 parameters. This document discusses some use of such parameters in IETF protocols and specifies IANA considerations for allocation of code points under the IANA OUI (Organizationally Unique Identifier).
1. Introduction ....................................................3 1.1. Notations Used in This Document ............................3 1.2. The IEEE Registration Authority ............................3 1.2.1. The IANA OUI ........................................4 1.3. Acknowledgements ...........................................4 2. Ethernet Identifier Parameters ..................................4 2.1. 48-Bit MAC Identifiers and OUIs ............................4 2.1.1. EUI-48 Allocations under the IANA OUI ...............5 2.1.2. EUI-48 IANA Allocation Considerations ...............5 2.2. 64-Bit MAC Identifiers .....................................6 2.2.1. IPv6 Use of Modified EUI-64 Identifiers .............6 2.2.2. EUI-64 IANA Allocation Considerations ...............8 2.3. Other MAC-48 Identifiers Used by IETF ......................9 2.3.1. Identifiers Prefixed 33-33 ..........................9 2.3.2. The 'CF Series' ....................................10 188.8.131.52. Changes to RFC 2153 .......................10 3. Ethernet Protocol Parameters ...................................10 3.1. Ethernet Protocol Allocation under the IANA OUI ...........12 4. Other OUI-Based Parameters .....................................13 5. IANA Considerations ............................................13 5.1. Expert Review and IESG Ratification .......................14 5.2. Informational IANA Web Page Material ......................15 5.3. OUI Exhaustion ............................................15 6. Security Considerations ........................................15 7. Normative References ...........................................15 8. Informative References .........................................16 Appendix A. Templates ............................................18 A.1. EUI-48/EUI-64 Identifier or Identifier Block Template .....18 A.2. 5-Octet Ethernet Protocol Identifier Template .............18 A.3. Other IANA OUI-Based Parameter Template ...................19 Appendix B. Ethertypes ............................................19 B.1. Some Ethertypes Specified by The IETF .....................19 B.2. Some IEEE 802 Ethertypes ..................................20
IEEE] 802 related communication frame formats and parameters [IEEE802]. These include MAC (Media Access Control) identifiers and protocol identifiers. This document specifies IANA considerations for the allocation of code points under the IANA OUI. It also discusses some other IETF use of IEEE 802 code points. [RFC5226] is incorporated herein except where there are contrary provisions in this document. 802.3] link is from the lowest order bit to the highest order bit (i.e., the reverse of the IETF's ordering). In this document: "IAB" stands for Individual Address Block, not for Internet Architecture Board; "MAC" stands for Media Access Control, not for Message Authentication Code; and "OUI" stands for Organizationally Unique Identifier. "**" indicates exponentiation. For example, 2**24 is two to the twenty-fourth power. http://standards.ieee.org/regauth/ Anyone may apply to that Authority for parameters. They may impose fees or other requirements but commonly waive fees for applications from standards development organizations.
A list of some allocated OUIs and IABs and their holders is downloadable from the IEEE Registration Authority site. Section 2.1 discusses EUI-48 (Extended Unique Identifier 48) MAC identifiers, their relationship to OUIs and IABs, and allocations under the IANA OUI. Section 2.2 extends this to EUI-64 identifiers. Section 2.3 discusses other IETF MAC identifier use not under the IANA OUI. 802_O&A]. Two bits within the initial 3 octets of an EUI-48 have special significance: the Group bit (01-00-00) and the Local bit (02-00-00). OUIs and IABs are allocated with the Local bit zero and the Group bit unspecified. Multicast identifiers may be constructed by turning on the Group bit, and unicast identifiers constructed by leaving the Group bit zero.
For globally unique EUI-48 identifiers allocated by an OUI or IAB owner, the Local bit is zero. If the Local bit is a one, the identifier is considered by IEEE 802 to be a local identifier under the control of the local network administrator. If the Local bit is on, the holder of an OUI (or IAB) has no special authority over 48-bit MAC identifiers whose first 3 (or 4 1/2) octets correspond to their OUI (or IAB). Section 1.2.1 above. This includes 2**24 EUI-48 multicast identifiers from 01-00-5E-00-00-00 to 01-00-5E-FF-FF-FF and 2**24 EUI-48 unicast identifiers from 00-00-5E-00-00-00 to 00-00-5E-FF-FF-FF. Of these EUI-48 identifiers, the following allocations have been made thus far: o The 2**23 multicast identifiers from 01-00-5E-00-00-00 through 01-00-5E-7F-FF-FF have been allocated for IPv4 multicast [RFC1112]. o The 2**20 multicast identifiers from 01-00-5E-80-00-00 through 01-00-5E-8F-FF-FF have been allocated for MPLS multicast [RFC5332]. o The 2**8 unicast identifiers from 00-00-5E-00-00-00 through 00-00-5E-00-00-FF are reserved and require IESG Ratification for allocation (see Section 5.1). o The 2**8 unicast identifiers from 00-00-5E-00-01-00 through 00-00-5E-00-01-FF have been allocated for the Virtual Router Redundancy Protocol (VRRP) [RFC3768]. Section 5.2) must meet the following requirements: o must be for standards purposes (either for an IETF Standard or other standard related to IETF work), o must be for a block of a power-of-two identifiers starting at a boundary that is an equal or greater power of two, including the allocation of one (2**0) identifier, o must not be used to evade the requirement for vendors to obtain their own block of identifiers from the IEEE, and
o must be documented in an Internet-Draft or RFC. In addition, approval must be obtained as follows (see the procedure in Section 5.1): Small to medium allocations of a block of 1, 2, 4, ..., 32768, 65536 (2**0, 2**1, 2**2, ..., 2**15, 2**16) EUI-48 identifiers require Expert Review. Large allocations of 131072 (2**17) or more EUI-48 identifiers require IESG Ratification (see Section 5.1). To simplify record keeping, all future allocations of 256 (2**8) or fewer identifiers shall have the Group bit unspecified, that is, shall be allocations of parallel equal-size blocks of multicast and unicast identifiers, even if one of these two types is not needed for the proposed use. The only exception is that requests for unicast- only identifier blocks of any size may be allocated out of the remaining identifiers in the large unicast range from 00-00-5E-00-02-00 to 00-00-5E-8F-FF-FF. Section 2.5.1 and Appendix A of [RFC4291] and Appendix A of [RFC5214]). When so used, the MAC-64 is modified by inverting the Local/Global bit to form an IETF "Modified EUI-64 identifier". Below
is an illustration of a Modified EUI-64 identifier under the IANA OUI, where aa-bb-cc-dd-ee is the extension. 02-00-5E-aa-bb-cc-dd-ee The first octet is shown as 02 rather than 00 because, in Modified EUI-64 identifiers, the sense of the Local/Global bit is inverted compared with EUI-48 identifiers. It is the globally unique values (universal scope) that have the 02 bit on in the first octet, while those with this bit off are locally assigned and out of scope for global allocation. The Local/Global bit was inverted to make it easier for network operators to type in local-scope identifiers. Thus, such Modified EUI-64 identifiers as 1, 2, etc. (ignoring leading zeros), are local. Without the modification, they would have to be 02-00-00-00-00-00-00-01, 02-00-00-00-00-00-00-02, etc., to be local. As with MAC-48 identifiers, the 01 bit on in the first octet indicates a group identifier. When the first two octets of the extension of a Modified EUI-64 identifier are FF-FE, the remainder of the extension is a 24-bit value as assigned by the OUI owner for an EUI-48. For example: 02-00-5E-FF-FE-yy-yy-yy or 03-00-5E-FF-FE-yy-yy-yy where yy-yy-yy is the portion (of an EUI-48 global unicast or multicast identifier) that is assigned by the OUI owner (IANA in this case). Thus, any holder of one or more EUI-48 identifiers under the IANA OUI also has an equal number of Modified EUI-64 identifiers that can be formed by inserting FF-FE in the middle of their EUI-48 identifiers and inverting the Local/Global bit. (Note: [EUI-64] defines FF-FF as the bits to be inserted to create an IEEE EUI-64 identifier from a MAC-48 identifier. That document says the FF-FE value is used when starting with an EUI-48 identifier. The IETF uses only FF-FE to create Modified EUI-64 identifiers from 48-bit Ethernet station identifiers regardless of whether they are EUI-48 or MAC-48 local identifiers. EUI-48 and local MAC-48 identifiers are syntactically equivalent, and this doesn't cause any problems in practice.)
In addition, certain Modified EUI-64 identifiers under the IANA OUI are reserved for holders of IPv4 addresses as follows: 02-00-5E-FE-xx-xx-xx-xx where xx-xx-xx-xx is a 32-bit IPv4 address. For Modified EUI-64 identifiers based on an IPv4 address, the Local/Global bit should be set to correspond to whether the IPv4 address is local or global. (Keep in mind that the sense of the Modified EUI-64 identifier Local/Global bit is reversed from that in (unmodified) MAC-64 identifiers.) Section 5.1) for allocation. IANA EUI-64 identifier allocations under the IANA OUI must meet the following requirements: o must be for standards purposes (either for an IETF Standard or other standard related to IETF work), o must be for a block of a power-of-two identifiers starting at a boundary which is an equal or greater power of two, including the allocation of one (2**0) identifier, o must not be used to evade the requirement for vendors to obtain their own block of identifiers from the IEEE, and
o must be documented in an Internet Draft or RFC. In addition, approval must be obtained as follows (see the procedure in Section 5.1): Small to medium allocations of a block of 1, 2, 4, ..., 134217728, 268435456 (2**0, 2**1, 2**2, ..., 2**27, 2**28) EUI-64 identifiers require Expert Review. Allocations of any size, including 536870912 (2**29) or more EUI-64 identifiers, may be made with IESG Ratification (see Section 5.1). To simplify record keeping, all allocations of 65536 (2**16) or less EUI-64 identifiers shall have the Group bit unspecified, that is, shall be allocations of parallel equal size blocks of multicast and unicast identifiers, even if one of these two types is not needed for the proposed use. RFC2464]. In all these identifiers, the Group bit (the bottom bit of the first octet) is on, as is required to work properly with existing hardware as a multicast identifier. They also have the Local bit on and are used for this purpose in IPv6 networks. (Historical note: It was the custom during IPv6 design to use "3" for unknown or example values, and 3333 Coyote Hill Road, Palo Alto, California, is the address of PARC (Palo Alto Research Center, formerly "Xerox PARC"). Ethernet was originally specified by Digital Equipment Corporation, Intel Corporation, and Xerox Corporation. The pre IEEE [802.3] Ethernet protocol has sometimes been known as "DIX" Ethernet from the first letters of the names of these companies.)
RFC2153] declared the 3-octet values from CF-00-00 through CF-FF-FF to be OUIs available for allocation by IANA to software vendors for use in PPP [RFC1661] or for other uses where vendors do not otherwise need an IEEE-assigned OUI. It should be noted that, when used as MAC-48 prefixes, these values have the Local and Group bits on, while all IEEE-allocated OUIs have those bits off. The Group bit is meaningless in PPP. To quote [RFC2153]: "The 'CF0000' series was arbitrarily chosen to match the PPP NLPID 'CF', as a matter of mnemonic convenience." CF-00-00 is reserved, and IANA lists multicast identifier CF-00-00-00-00-00 as used for Ethernet loopback tests. In over a decade of availability, only a handful of values in the 'CF Series' have been allocated. (See http://www.iana.org under both Ethernet Parameters and PPP Parameters.) RFC2153] are updated as follows (no technical changes are made): Use of these identifiers based on IANA allocation is deprecated. IANA is directed not to allocate any further values in the 'CF Series'. 802_O&A] world, tags are fixed length and do not include any encoding of their own length. Thus, anything that is processing a frame cannot, in general, safely process anything in the frame past an Ethertype it does not understand. An example is the C-tag (formerly the Q-tag) [802.1Q]. It provides customer VLAN and priority information for a frame. There are two types of protocol identifier parameters that can occur in Ethernet frames after the initial MAC-48 destination and source identifiers:
Ethertypes: These are 16-bit identifiers appearing as the initial two octets after the MAC destination and source (or after a tag) which, when considered as an unsigned integer, are equal to or larger than 0x0600. LSAPs: These are 8-bit protocol identifiers that occur in pairs immediately after an initial 16-bit (two octet) remaining frame length, which is in turn after the MAC destination and source (or after a tag). Such a length must, when considered as an unsigned integer, be less than 0x5DC or it could be mistaken as an Ethertype. LSAPs (Link-Layer Subnet Access Points) occur in pairs where one is intended to indicate the source protocol handler and one the destination protocol handler; however, use cases where the two are different have been relatively rare. Neither Ethertypes nor LSAPs are allocated by IANA; instead, they are allocated by the IEEE Registration Authority (see Section 1.2 above and the Ethertype Annex below). However, both LSAPs and Ethertypes have extension mechanisms so that they can be used with five-octet Ethernet protocol identifiers under an OUI, including those allocated by IANA under the IANA OUI. When using the IEEE 802 LLC format (SNAP) [802_O&A] for a frame, an OUI-based protocol identifier can be expressed as follows: xx-xx-AA-AA-03-yy-yy-yy-zz-zz where xx-xx is the frame length and, as above, must be small enough not to be confused with an Ethertype; "AA" is the LSAP that indicates this use and is sometimes referred to as the SNAP SAP; "03" is the LLC control octet indicating datagram service; yy-yy-yy is an OUI; and zz-zz is a protocol number, under that OUI, allocated by the OUI owner. The odd five-octet length for such OUI-based protocol identifiers was chosen so that, with the LLC control octet ("03"), the result is 16-bit aligned. When using an Ethertype to indicate the main type for a frame body, the special "OUI Extended Ethertype" 88-B7 is available. Using this Ethertype, a frame body can begin with 88-B7-yy-yy-yy-zz-zz where yy-yy-yy and zz-zz have the same meaning as in the SNAP format described above. It is also possible, within the SNAP format, to use an arbitrary Ethertype. Putting the Ethertype as the zz-zz field after an all zeros OUI (00-00-00) does this. It looks like
xx-xx-AA-AA-03-00-00-00-zz-zz where zz-zz is the Ethertype. (Note that, at this point, the 802 protocol syntax facilities are sufficiently powerful that they could be chained indefinitely. Whether support for such chaining is generally required is not clear, but [802_O&A] requires support for xx-xx-AA-AA-03-00-00-00-88-B7-yy-yy-yy-zz-zz even though this could be more efficiently expressed by simply pinching out the "00-00-00-88-B7" in the middle.) As well as labeling frame contents, 802 Protocol types appear within NBMA (Non-Broadcast Multi-Access) Next Hop Resolution Protocol [RFC2332] messages. Such messages have provisions for both two octet Ethertypes and OUI based protocol types. IANA]). The extreme values of this range, 00-00-5E-00-00 and 00-00-5E-FF-FF, are reserved and require IESG Ratification for allocation (see Section 5.1). New allocations of SNAP SAP protocol (zz-zz) numbers under the IANA OUI must meet the following requirements: o the allocation must be for standards use (either for an IETF Standard or other standard related to IETF work), o it must be documented in an Internet-Draft or RFC, and o such protocol numbers are not to be allocated for any protocol that has an Ethertype (because that can be expressed by putting an all zeros "OUI" before the Ethertype as described above). In addition, the Expert Review (or IESG Ratification for the two reserved values) must be obtained using the procedure specified in Section 5.1.
802.11], page 125). Values may be allocated under the IANA OUI for such other OUI-based parameter usage by Expert Review except that, for each use, the additional specifier values consisting of all zero bits and all one bits (0x00 and 0xFF for a one-octet specifier) are reserved and require IESG Ratification (see Section 5.1) for allocation. The allocations must be for standards use (either for an IETF Standard or other standard related to IETF work) and be documented in an Internet-Draft or RFC. The first time a value is allocated for a particular parameter of this type, an IANA registry will be created to contain that allocation and any subsequent allocations of values for that parameter under the IANA OUI. The Expert will specify the name of the registry. (If a different policy from that above is required for such a parameter, a BCP or Standards Track RFC must be adopted updating this BCP and specifying the new policy and parameter.) Section 1.2.1 provides information on the IANA-assigned OUI. Section 2.1.1 lists current EUI-48 assignments under this OUI. Section 2.1.2 specifies IANA considerations for EUI-48 assignments. Section 2.2.2 specifies IANA considerations for EUI-64 assignments.
Section 3.1 provides a pointer to current protocol identifier assignments under the IANA OUI, and specifies IANA considerations for protocol identifier assignments. Section 4 briefly provides IANA considerations relating to OUI- based miscellaneous allocations. Section 4.1 of [RFC5226]. While finite, the universe of code points from which Expert judged allocations will be made is felt to be large enough that the requirements given in this document and the Experts' good judgment are sufficient guidance. The idea is for the Expert to provide a light sanity check for small allocations of EUI identifiers with increased scrutiny by the Expert for medium-sized allocations of EUI identifiers, and allocations of protocol identifiers and other IANA OUI based parameters. However, it can make sense to allocate very large portions of the MAC identifier code point space. (Note that existing allocations include one for 1/2 of the entire multicast code point space and one for 1/16 of the multicast code point space.) In those cases, and in cases of the allocation of "reserved" values, IESG Ratification of an Expert Review approval recommendation is required as described below. The procedure is as follows: The applicant always completes the appropriate Template from the Template Annex below and sends it to IANA <email@example.com>. IANA always sends the Template to an appointed Expert. If the Expert recuses themselves or is non-responsive, IANA may choose an alternative appointed Expert or, if none are available, will contact the IESG. If the allocation is based on Expert Review: If IANA receives a disapproval from an Expert selected to review an application Template, the application will be denied. If IANA receives approval and code points are available, IANA will make the requested allocation.
If the allocation is based on IESG Ratification, the procedure starts with the first two steps above for Expert Review. If the Expert disapproves the application, they simply inform IANA; however, if the Expert believes the application should be approved, or is uncertain and believes that the circumstances warrant the attention of the IESG, the Expert will inform IANA about their advice and IANA will forward the application, together with the reasons for approval or uncertainty, to the IESG. The IESG must decide whether the allocation will be granted. This can be accomplished by a management item in an IESG telechat as done for other types of requests. If the IESG decides not to ratify a favorable opinion by the Expert or decides against an application where the Expert is uncertain, the application is denied, otherwise it is granted. The IESG will communicate its decision to the Expert and to IANA. Section 1.2) for further IANA allocation use. [802_O&A] "IEEE Standard for Local and Metropolitan Area Networks: Overview and Architecture", IEEE 802-2001, 8 March 2002. "IEEE Standard for Local and Metropolitan Area Networks: Overview and Architecture / Amendment 1: Ethertypes for Prototype and Vendor-Specific Protocol Development", IEEE 802a-2003, 18 September 2003.
[802.1Q] "IEEE Standard for Local and metropolitan area networks / Virtual Bridged Local Area Networks", IEEE 802.1Q-2005, 19 May 2006. [802.3] "IEEE Standard for Information technology / Telecommunications and information exchange between systems / Local and metropolitan area networks / Specific requirements / Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications", IEEE 802.3-2005, 9 December 2005. [802.11] "IEEE Standard for Information technology / Telecommunications and information exchange between systems / Local and metropolitan area networks / Specific requirements / Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications", IEEE 802.11-2007, 11 June 2007. [EUI-64] IEEE, "Guidelines for 64-bit Global Identifier (EUI-64) Registration Authority", <http://standards.ieee.org/ regauth/oui/tutorials/EUI64.html>, March 1997. [IANA] Internet Assigned Numbers Authority, Ethernet Types, <http://www.iana.org>. [IEEE] Institute of Electrical and Electronics Engineers, <http://www.ieee.org>. [IEEE802] IEEE 802 LAN/MAN (Local Area Network / Metropolitan Area Network) Standards Committee, <http://www.ieee802.org>. [RFC1112] Deering, S., "Host Extensions for IP Multicasting", STD 5, RFC 1112, Stanford University, August 1989. [RFC1661] Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51, RFC 1661, July 1994. [RFC2153] Simpson, W., "PPP Vendor Extensions", RFC 2153, May 1997. [RFC2332] Luciani, J., Katz, D., Piscitello, D., Cole, B., and N. Doraswamy, "NBMA Next Hop Resolution Protocol (NHRP)", RFC 2332, April 1998. [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet Networks", RFC 2464, December 1998.
[RFC3768] Hinden, R., "Virtual Router Redundancy Protocol (VRRP)", RFC 3768, April 2004. [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, February 2006. [RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214, March 2008. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. [RFC5332] Eckert, T., Rosen, E., Ed., Aggarwal, R., and Y. Rekhter, "MPLS Multicast Encapsulations", RFC 5332, August 2008.
IANA]. The IEEE Registration Authority page of Ethertypes, http://standards.ieee.org/regauth/ethertype/eth.txt, may also be useful. See Section 3 above.
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