Network Working Group P. Calhoun Internet-Draft Cisco Systems, Inc. Expires: September 14, 2008 March 13, 2008 CAPWAP Access Controller DHCP Option draft-ietf-capwap-dhc-ac-option-01 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 14, 2008. Calhoun Expires September 14, 2008 [Page 1]
Internet-Draft CAPWAP Access Controller DHCP Option March 2008 Abstract The Control And Provisioning of Wireless Access Points Protocol allows a Wireless Termination Point to use DHCP to discover the Access Controllers it is to connect to. This document describes the DHCP options to be used by the CAPWAP protocol. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. CAPWAP AC DHCPv4 Option . . . . . . . . . . . . . . . . . . . 4 3. CAPWAP AC DHCPv6 Option . . . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.1. Normative References . . . . . . . . . . . . . . . . . . . 10 7.2. Informational References . . . . . . . . . . . . . . . . . 10 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 11 Intellectual Property and Copyright Statements . . . . . . . . . . 12 Calhoun Expires September 14, 2008 [Page 2]
Internet-Draft CAPWAP Access Controller DHCP Option March 2008 1. Introduction The Control And Provisioning of Wireless Access Points Protocol (CAPWAP) [I-D.ietf-capwap-protocol-specification] allows a Wireless Termination Point (WTP) to use DHCP to discover the Access Controllers (AC) it is to connect to. Prior to the CAPWAP Discovery process, the WTP MAY use one of many methods to identify the proper AC to establish a CAPWAP connection with. One of these methods is through the DHCP protocol. This is done through the CAPWAP AC DHCPv4 or CAPWAP AC DHCPv6 Option. 1.1. Conventions used in this document 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]. 1.2. Terminology This document uses terminology defined in [RFC3753] and [I-D.ietf-capwap-protocol-specification]. Calhoun Expires September 14, 2008 [Page 3]
Internet-Draft CAPWAP Access Controller DHCP Option March 2008 2. CAPWAP AC DHCPv4 Option This section defines a DHCPv4 option that carries a list of 32-bit (binary) IPv4 addresses indicating one or more CAPWAP AC available to the WTP. The DHCPv4 option for CAPWAP has the format shown in the following figure: 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | option-code | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + AC IPv4 Address + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code: OPTION_CAPWAP_AC_V4 (TBD) option-length: Length of the 'options' field in octets; MUST be a multiple of four (4). AC IPv4 Address: IPv4 address of a CAPWAP AC which the WTP may use. The ACs are listed in the order of preference for use by the WTP. A CAPWAP WTP, acting as a DHCPv4 client, SHOULD request the CAPWAP AC DHCPv4 Option in a Parameter Request List as described in [RFC2131] and [RFC2132]. If configured with a (list of) CAPWAP AC address(es), a DHCPv4 server SHOULD send the client the CAPWAP AC DHCPv4 option, even if this option is not explicitly requested by the client. A CAPWAP WTP, acting as a DHCPv4 client, receiving the CAPWAP AC DHCPv4 option MAY use the (list of) IP address(es) to locate AC. The CAPWAP protocol [I-D.ietf-capwap-protocol-specification] provides guidance on the WTP's discovery process. The WTP, acting as a DHCPv4 client, SHOULD try the records in the order listed in the CAPWAP AC DHCPv4 option received from the DHCPv4 server. Calhoun Expires September 14, 2008 [Page 4]
Internet-Draft CAPWAP Access Controller DHCP Option March 2008 3. CAPWAP AC DHCPv6 Option This section defines a DHCPv6 option that carries a list of 128-bit (binary) IPv6 addresses indicating one or more CAPWAP AC available to the WTP. The DHCPv6 option for CAPWAP has the format shown in the following figure: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | option-code | option-length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | | + AC IPv6 Address + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | .... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ option-code: OPTION_CAPWAP_AC_V6 (TBD) option-length: Length of the 'options' field in octets; MUST be a multiple of sixteen (16). AC IPv6 Address: IPv6 address of a CAPWAP AC which the WTP may use. The ACs are listed in the order of preference for use by the WTP. A CAPWAP WTP, acting as a DHCPv6 client, SHOULD request the CAPWAP AC DHCPv6 Option in a Parameter Request List as described in [RFC2131] and [RFC2132]. If configured with a (list of) CAPWAP AC address(es), a DHCPv6 server SHOULD send the client the CAPWAP AC DHCPv6 option, even if this option is not explicitly requested by the client. A CAPWAP WTP, acting as a DHCPv6 client, receiving the CAPWAP AC DHCPv6 option MAY use the (list of) IP address(es) to locate AC. The CAPWAP protocol [I-D.ietf-capwap-protocol-specification] provides guidance on the WTP's discovery process. The WTP, acting as a DHCPv6 client, SHOULD try the records in the order listed in the CAPWAP AC DHCPv6 option received from the DHCPv6 Calhoun Expires September 14, 2008 [Page 5]
Internet-Draft CAPWAP Access Controller DHCP Option March 2008 server. Calhoun Expires September 14, 2008 [Page 6]
Internet-Draft CAPWAP Access Controller DHCP Option March 2008 4. IANA Considerations The following DHCPv4 option code for CAPWAP AC option MUST be assigned by IANA: Option Name Value Described in ----------------------------------------------- OPTION_CAPWAP_AC_V4 TBD Section 2 The following DHCPv6 option code for CAPWAP AC options MUST be assigned by IANA: Option Name Value Described in ------------------------------------------------ OPTION_CAPWAP_AC_V6 TBD Section 3 Calhoun Expires September 14, 2008 [Page 7]
Internet-Draft CAPWAP Access Controller DHCP Option March 2008 5. Security Considerations The security considerations in [RFC2131], [RFC2132] and [RFC3315] apply. If an adversary manages to modify the response from a DHCP server or insert its own response, a WTP could be led to contact a rogue CAPWAP AC, possibly one that then intercepts call requests or denies service. CAPWAP's use of DTLS MUST be used to authenticate the CAPWAP peers in the establishment of the session. In most of the networks, the DHCP exchange that delivers the options prior to network access authentication is neither integrity protected nor origin authenticated. Therefore, the options defined in this document are not the only methods used to determine which AC a WTP should connect to. The CAPWAP protocol [I-D.ietf-capwap-protocol-specification] defines other AC discovery procedures a WTP MAY utilize. Calhoun Expires September 14, 2008 [Page 8]
Internet-Draft CAPWAP Access Controller DHCP Option March 2008 6. Acknowledgements The following individuals are acknowledged for their contributions to this protocol specification: Ralph Droms, Margaret Wasserman. Calhoun Expires September 14, 2008 [Page 9]
Internet-Draft CAPWAP Access Controller DHCP Option March 2008 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor Extensions", RFC 2132, March 1997. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. [I-D.ietf-capwap-protocol-specification] Calhoun, P., "CAPWAP Protocol Specification", draft-ietf-capwap-protocol-specification-10 (work in progress), March 2008. 7.2. Informational References [RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology", RFC 3753, June 2004. Calhoun Expires September 14, 2008 [Page 10]
Internet-Draft CAPWAP Access Controller DHCP Option March 2008 Author's Address Pat R. Calhoun Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134 Phone: +1 408-853-5269 Email: pcalhoun@cisco.com Calhoun Expires September 14, 2008 [Page 11]
Internet-Draft CAPWAP Access Controller DHCP Option March 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Calhoun Expires September 14, 2008 [Page 12]