draft-ietf-capwap-dhc-ac-option-00.txt   draft-ietf-capwap-dhc-ac-option-01.txt 
Network Working Group P. Calhoun Network Working Group P. Calhoun
Internet-Draft Cisco Systems, Inc. Internet-Draft Cisco Systems, Inc.
Expires: December 14, 2007 June 12, 2007 Expires: September 14, 2008 March 13, 2008
CAPWAP Access Controller DHCP Option CAPWAP Access Controller DHCP Option
draft-ietf-capwap-dhc-ac-option-00 draft-ietf-capwap-dhc-ac-option-01
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Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract Abstract
The Control And Provisioning of Wireless Access Points Protocol The Control And Provisioning of Wireless Access Points Protocol
allows a Wireless Termination Point to use DHCP to discover the allows a Wireless Termination Point to use DHCP to discover the
Access Controllers it is to connect to. This document describes the Access Controllers it is to connect to. This document describes the
DHCP options to be used by the CAPWAP protocol. DHCP options to be used by the CAPWAP protocol.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions used in this document . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. CAPWAP AC DHCPv4 Option . . . . . . . . . . . . . . . . . . . 4 2. CAPWAP AC DHCPv4 Option . . . . . . . . . . . . . . . . . . . 4
3. CAPWAP AC DHCPv6 Option . . . . . . . . . . . . . . . . . . . 5 3. CAPWAP AC DHCPv6 Option . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1. Normative References . . . . . . . . . . . . . . . . . . . 9 7.1. Normative References . . . . . . . . . . . . . . . . . . . 10
7.2. Informational References . . . . . . . . . . . . . . . . . 9 7.2. Informational References . . . . . . . . . . . . . . . . . 10
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 11
Intellectual Property and Copyright Statements . . . . . . . . . . 11 Intellectual Property and Copyright Statements . . . . . . . . . . 12
1. Introduction 1. Introduction
The Control And Provisioning of Wireless Access Points Protocol The Control And Provisioning of Wireless Access Points Protocol
(CAPWAP) [5] allows a Wireless Termination Point (WTP) to use DHCP to (CAPWAP) [I-D.ietf-capwap-protocol-specification] allows a Wireless
discover the Access Controllers (AC) it is to connect to. 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 Prior to the CAPWAP Discovery process, the WTP MAY use one of many
methods to identify the proper AC to establish a CAPWAP connection methods to identify the proper AC to establish a CAPWAP connection
with. One of these methods is through the DHCP protocol. This is with. One of these methods is through the DHCP protocol. This is
done through the CAPWAP AC DHCPv4 or CAPWAP AC DHCPv6 Option. done through the CAPWAP AC DHCPv4 or CAPWAP AC DHCPv6 Option.
1.1. Conventions used in this document 1.1. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [1]. document are to be interpreted as described in RFC 2119 [RFC2119].
1.2. Terminology 1.2. Terminology
This document uses terminology defined in [6] and [5]. This document uses terminology defined in [RFC3753] and
[I-D.ietf-capwap-protocol-specification].
2. CAPWAP AC DHCPv4 Option 2. CAPWAP AC DHCPv4 Option
This section defines a DHCPv4 option that carries a list of 32-bit This section defines a DHCPv4 option that carries a list of 32-bit
(binary) IPv4 addresses indicating one or more CAPWAP AC available to (binary) IPv4 addresses indicating one or more CAPWAP AC available to
the WTP. the WTP.
The DHCPv4 option for CAPWAP has the format shown in the following The DHCPv4 option for CAPWAP has the format shown in the following
figure: figure:
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option-code: OPTION_CAPWAP_AC_V4 (TBD) option-code: OPTION_CAPWAP_AC_V4 (TBD)
option-length: Length of the 'options' field in octets; MUST be a option-length: Length of the 'options' field in octets; MUST be a
multiple of four (4). multiple of four (4).
AC IPv4 Address: IPv4 address of a CAPWAP AC which the WTP may use. 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. 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 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 DHCPv4 Option in a Parameter Request List as described in [RFC2131]
[3]. and [RFC2132].
If configured with a (list of) CAPWAP AC address(es), a DHCPv4 server 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 SHOULD send the client the CAPWAP AC DHCPv4 option, even if this
option is not explicitly requested by the client. option is not explicitly requested by the client.
A CAPWAP WTP, acting as a DHCPv4 client, receiving the CAPWAP AC 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 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. 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 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 order listed in the CAPWAP AC DHCPv4 option received from the DHCPv4
server. server.
3. CAPWAP AC DHCPv6 Option 3. CAPWAP AC DHCPv6 Option
This section defines a DHCPv6 option that carries a list of 128-bit This section defines a DHCPv6 option that carries a list of 128-bit
(binary) IPv6 addresses indicating one or more CAPWAP AC available to (binary) IPv6 addresses indicating one or more CAPWAP AC available to
the WTP. the WTP.
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option-code: OPTION_CAPWAP_AC_V6 (TBD) option-code: OPTION_CAPWAP_AC_V6 (TBD)
option-length: Length of the 'options' field in octets; MUST be a option-length: Length of the 'options' field in octets; MUST be a
multiple of sixteen (16). multiple of sixteen (16).
AC IPv6 Address: IPv6 address of a CAPWAP AC which the WTP may use. 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. 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 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 DHCPv6 Option in a Parameter Request List as described in [RFC2131]
[3]. and [RFC2132].
If configured with a (list of) CAPWAP AC address(es), a DHCPv6 server 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 SHOULD send the client the CAPWAP AC DHCPv6 option, even if this
option is not explicitly requested by the client. option is not explicitly requested by the client.
A CAPWAP WTP, acting as a DHCPv6 client, receiving the CAPWAP AC 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 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. 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 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 order listed in the CAPWAP AC DHCPv6 option received from the DHCPv6
server. server.
4. IANA Considerations 4. IANA Considerations
The following DHCPv4 option code for CAPWAP AC option MUST be The following DHCPv4 option code for CAPWAP AC option MUST be
assigned by IANA: assigned by IANA:
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The following DHCPv6 option code for CAPWAP AC options MUST be The following DHCPv6 option code for CAPWAP AC options MUST be
assigned by IANA: assigned by IANA:
Option Name Value Described in Option Name Value Described in
------------------------------------------------ ------------------------------------------------
OPTION_CAPWAP_AC_V6 TBD Section 3 OPTION_CAPWAP_AC_V6 TBD Section 3
5. Security Considerations 5. Security Considerations
The security considerations in [2], [3] and [4] apply. If an The security considerations in [RFC2131], [RFC2132] and [RFC3315]
adversary manages to modify the response from a DHCP server or insert apply. If an adversary manages to modify the response from a DHCP
its own response, a WTP could be led to contact a rogue CAPWAP AC, server or insert its own response, a WTP could be led to contact a
possibly one that then intercepts call requests or denies service. rogue CAPWAP AC, possibly one that then intercepts call requests or
CAPWAP's use of DTLS MUST be used to authenticate the CAPWAP peers in denies service. CAPWAP's use of DTLS MUST be used to authenticate
the establishment of the session. the CAPWAP peers in the establishment of the session.
In most of the networks, the DHCP exchange that delivers the options In most of the networks, the DHCP exchange that delivers the options
prior to network access authentication is neither integrity protected prior to network access authentication is neither integrity protected
nor origin authenticated. Therefore, the options defined in this nor origin authenticated. Therefore, the options defined in this
document are not the only methods used to determine which AC a WTP document are not the only methods used to determine which AC a WTP
should connect to. The CAPWAP protocol [5] defines other AC should connect to. The CAPWAP protocol
discovery procedures a WTP MAY utilize. [I-D.ietf-capwap-protocol-specification] defines other AC discovery
procedures a WTP MAY utilize.
6. Acknowledgements 6. Acknowledgements
The following individuals are acknowledged for their contributions to The following individuals are acknowledged for their contributions to
this protocol specification: Ralph Droms, Margaret Wasserman. this protocol specification: Ralph Droms, Margaret Wasserman.
7. References 7. References
7.1. Normative References 7.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[2] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, [RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
March 1997. RFC 2131, March 1997.
[3] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997. Extensions", RFC 2132, March 1997.
[4] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", and M. Carney, "Dynamic Host Configuration Protocol for
RFC 3315, July 2003. IPv6 (DHCPv6)", RFC 3315, July 2003.
[3] Calhoun, P., Montemurro, M., Stanley, D., "CAPWAP Protocol [I-D.ietf-capwap-protocol-specification]
Specification", draft-ietf-capwap-protocol-specification-07 Calhoun, P., "CAPWAP Protocol Specification",
(work in progress), June 2007. draft-ietf-capwap-protocol-specification-10 (work in
progress), March 2008.
7.2. Informational References 7.2. Informational References
[6] Manner, J. and M. Kojo, "Mobility Related Terminology", [RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology",
RFC 3753, June 2004. RFC 3753, June 2004.
Author's Address Author's Address
Pat R. Calhoun Pat R. Calhoun
Cisco Systems, Inc. Cisco Systems, Inc.
170 West Tasman Drive 170 West Tasman Drive
San Jose, CA 95134 San Jose, CA 95134
Phone: +1 408-853-5269 Phone: +1 408-853-5269
Email: pcalhoun@cisco.com Email: pcalhoun@cisco.com
Full Copyright Statement Full Copyright Statement
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
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