[Docs] [txt|pdf] [Tracker] [WG] [Email] [Nits]

Versions: 00 01 02 RFC 5417

Network Working Group                                         P. Calhoun
Internet-Draft                                       Cisco Systems, Inc.
Expires: December 14, 2007                                 June 12, 2007


                  CAPWAP Access Controller DHCP Option
                   draft-ietf-capwap-dhc-ac-option-00

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 December 14, 2007.

Copyright Notice

   Copyright (C) The IETF Trust (2007).















Calhoun                 Expires December 14, 2007               [Page 1]

Internet-Draft    CAPWAP Access Controller DHCP Option         June 2007


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  . . . . . . . . . . . . . . . . . . . . .  6
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  7
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  8
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     7.1.  Normative References . . . . . . . . . . . . . . . . . . .  9
     7.2.  Informational References . . . . . . . . . . . . . . . . .  9
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
   Intellectual Property and Copyright Statements . . . . . . . . . . 11




























Calhoun                 Expires December 14, 2007               [Page 2]

Internet-Draft    CAPWAP Access Controller DHCP Option         June 2007


1.  Introduction

   The Control And Provisioning of Wireless Access Points Protocol
   (CAPWAP) [5] 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 [1].

1.2.  Terminology

   This document uses terminology defined in [6] and [5].































Calhoun                 Expires December 14, 2007               [Page 3]

Internet-Draft    CAPWAP Access Controller DHCP Option         June 2007


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 [2] and
   [3].

   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 [5] 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 December 14, 2007               [Page 4]

Internet-Draft    CAPWAP Access Controller DHCP Option         June 2007


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 [2] and
   [3].

   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 [5] 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
   server.



Calhoun                 Expires December 14, 2007               [Page 5]

Internet-Draft    CAPWAP Access Controller DHCP Option         June 2007


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 December 14, 2007               [Page 6]

Internet-Draft    CAPWAP Access Controller DHCP Option         June 2007


5.  Security Considerations

   The security considerations in [2], [3] and [4] 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 [5] defines other AC
   discovery procedures a WTP MAY utilize.




































Calhoun                 Expires December 14, 2007               [Page 7]

Internet-Draft    CAPWAP Access Controller DHCP Option         June 2007


6.  Acknowledgements

   The following individuals are acknowledged for their contributions to
   this protocol specification: Ralph Droms, Margaret Wasserman.















































Calhoun                 Expires December 14, 2007               [Page 8]

Internet-Draft    CAPWAP Access Controller DHCP Option         June 2007


7.  References

7.1.  Normative References

   [1]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.

   [2]  Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
        March 1997.

   [3]  Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
        Extensions", RFC 2132, March 1997.

   [4]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M.
        Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
        RFC 3315, July 2003.

   [3]  Calhoun, P., Montemurro, M., Stanley, D., "CAPWAP Protocol
        Specification", draft-ietf-capwap-protocol-specification-07
                (work in progress), June 2007.

7.2.  Informational References

   [6]  Manner, J. and M. Kojo, "Mobility Related Terminology",
        RFC 3753, June 2004.


























Calhoun                 Expires December 14, 2007               [Page 9]

Internet-Draft    CAPWAP Access Controller DHCP Option         June 2007


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 December 14, 2007              [Page 10]

Internet-Draft    CAPWAP Access Controller DHCP Option         June 2007


Full Copyright Statement

   Copyright (C) The IETF Trust (2007).

   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.


Acknowledgment

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).





Calhoun                 Expires December 14, 2007              [Page 11]


Html markup produced by rfcmarkup 1.109, available from https://tools.ietf.org/tools/rfcmarkup/