IANA Allocation Guidelines for the Address Resolution Protocol (ARP)
draft-arkko-arp-iana-rules-02

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Abstract

This document specifies the IANA guidelines for allocating new values in the Address Resolution Protocol (ARP). This document also reserves some numbers for experimentation purposes. The changes also affect other protocols that employ values from the ARP name spaces.

1.  Introduction

This document specifies the IANA guidelines [RFC5226] (Narten, T. and H. Alvestrand, “Guidelines for Writing an IANA Considerations Section in RFCs,” May 2008.) for allocating new values for various fields in the Address Resolution Protocol (ARP) [RFC0826] (Plummer, D., “Ethernet Address Resolution Protocol: Or converting network protocol addresses to 48.bit Ethernet address for transmission on Ethernet hardware,” November 1982.). The change is also applicable to extensions of ARP that use the same message format, such as [RFC0903] (Finlayson, R., Mann, T., Mogul, J., and M. Theimer, “Reverse Address Resolution Protocol,” June 1984.) and [RFC2390] (Bradley, T., Brown, C., and A. Malis, “Inverse Address Resolution Protocol,” September 1998.).

The change also affects other protocols that employ values from the ARP name spaces. For instance, the ARP hardware address type (ar$hrd) number space is also used in the "htype" (hardware address type) fields in Bootstrap Protocol (BOOTP) [RFC0951] (Croft, B. and J. Gilmore, “Bootstrap Protocol,” September 1985.) and Dynamic Host Configuration Protocol (DHCP) [RFC2131] (Droms, R., “Dynamic Host Configuration Protocol,” March 1997.), as well as in the "hardware type" field in the DHCP Unique Identifiers in DHCPv6 [RFC3315] (Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, “Dynamic Host Configuration Protocol for IPv6 (DHCPv6),” July 2003.). These protocols are therefore affected by the update in the IANA rules. Other affected specifications include the specialized address resolution mechanisms in HYPERchannel [RFC1044] (Hardwick, K. and J. Lekashman, “Internet Protocol on Network System's HYPERchannel: Protocol specification,” February 1988.), DHCP options [RFC2132] (Alexander, S. and R. Droms, “DHCP Options and BOOTP Vendor Extensions,” March 1997.), [RFC4361] (Lemon, T. and B. Sommerfeld, “Node-specific Client Identifiers for Dynamic Host Configuration Protocol Version Four (DHCPv4),” February 2006.), ATM (Asynchronous Transfer Mode) ARP [RFC2225] (Laubach, M. and J. Halpern, “Classical IP and ARP over ATM,” April 1998.), HARP (High-Performance Parallel Interface ARP) [RFC2834] (Pittet, J., “ARP and IP Broadcast over HIPPI-800,” May 2000.), [RFC2835] (Pittet, J., “IP and ARP over HIPPI-6400 (GSN),” May 2000.), FC (Fibre Channel) ARP [RFC4338] (DeSanti, C., Carlson, C., and R. Nixon, “Transmission of IPv6, IPv4, and Address Resolution Protocol (ARP) Packets over Fibre Channel,” January 2006.), and DNS Resource Records [RFC4701] (Stapp, M., Lemon, T., and A. Gustafsson, “A DNS Resource Record (RR) for Encoding Dynamic Host Configuration Protocol (DHCP) Information (DHCID RR),” October 2006.).

The IANA guidelines are given in Section 2 (IANA Considerations). Previously, no IANA guidance existed for such allocations.

This document also reserves some numbers for experimentation purposes. These numbers are given in Section 3 (Allocations Defined in This Document).

2.  IANA Considerations

The following rules apply to the fields of ARP:

ar$hrd (16 bits) Hardware address space

Requests for individual new ar$hrd values are made through First Come First Served [RFC5226] (Narten, T. and H. Alvestrand, “Guidelines for Writing an IANA Considerations Section in RFCs,” May 2008.). Requests for ar$hrd values below 256 or a batch of several new values are made through Expert Review [RFC5226]. Note that certain protocols, such as BOOTP and DHCPv4 employ these values within a 8 bit field. The expert should determine that the need to allocate the new values exists and that the existing values are insufficient to represent the new hardware address types. The expert should also determine the applicability of the request, and assign values higher than 255 for requests that do not apply to BOOTP/DHCPv4. Similarly, the expert should assign one-octet values for requests that clearly apply to BOOTP/DHCPv4 but not ARP, as for example the "IPsec tunnel" with value 31 [RFC3456] (Patel, B., Aboba, B., Kelly, S., and V. Gupta, “Dynamic Host Configuration Protocol (DHCPv4) Configuration of IPsec Tunnel Mode,” January 2003.). Conversely, ARP-only uses should favor 2-octet values.

ar$pro (16 bits) Protocol address space

These numbers share the Ethertype space. The Ethertype space is administered as described in [RFC5342] (Eastlake. , D., “IANA Considerations and IETF Protocol Usage for IEEE 802 Parameters,” September 2008.).

ar$op (16 bits) Opcode

Requests for new ar$op values are made through IETF Review or IESG Approval [RFC5226] (Narten, T. and H. Alvestrand, “Guidelines for Writing an IANA Considerations Section in RFCs,” May 2008.).

3.  Allocations Defined in This Document

When testing new protocol extension ideas, it is often necessary to use an actual constant in order to use the new function, even when testing in a closed environment. This document reserves the following numbers for experimentation purposes in ARP:

• One new ar$hrd value is allocated for experimental purposes, HW_EXP (TBD).
• Two new values for the ar$op are allocated for experimental purposes, OP_EXP1 (TBD, but below 256) and OP_EXP2 (TBD, but above 255 and preferrably with different values in the least and most significant octets).

Note that [RFC5342] (Eastlake. , D., “IANA Considerations and IETF Protocol Usage for IEEE 802 Parameters,” September 2008.), Section B.2 lists two Ethertypes that can be used for experimental purposes.

In addition, for both ar$hrd and ar$op the values 0 and 65535 are marked as reserved. This means that they are not available for allocation.

4.  Security Considerations

This specification does not change the security properties of the affected protocols.

However, a few words are necessary about the use of the experimental code points defined in Section 3 (Allocations Defined in This Document). Potentially harmful side-effects from the use of the experimental values needs to be carefully evaluated before deploying any experiment across networks that the owner of the experiment does not entirely control. Guidance given in [RFC3692] (Narten, T., “Assigning Experimental and Testing Numbers Considered Useful,” January 2004.) about the use of experimental values needs to be followed.

5.  Acknowledgments

The lack of any current rules has come up as new values were requested from IANA. The author would like to thank Michelle Cotton in particular for bringing this issue up. When no rules exist, IANA consults the IESG for approval of the new values. The purpose of this specification is to establish the rules and allow IANA to operate based on the rules, without requiring confirmation from the IESG. The author would also like to thank Brian Carpenter, Thomas Narten, Scott Bradner, Donald Eastlake, Andrew G. Malis, Brian Haberman, and Dave Thaler for feedback.

6.  References

6.1. Normative References

6.2. Informative References

Appendix A.  Changes from the Original RFCs

This document specifies only the IANA rules associated with various fields in ARP. The specification of these rules also affects the allocation of corresponding fields in protocols listed in Section 1 (Introduction) that share the registry. This document does not make any changes in the operation of these protocols themselves.

Authors' Addresses

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