draft-ietf-capwap-dhc-ac-option-02.txt   rfc5417.txt 
Network Working Group P. Calhoun Network Working Group P. Calhoun
Internet-Draft Cisco Systems, Inc. Request for Comments: 5417 Cisco Systems, Inc.
Intended status: Standards Track October 15, 2008
Expires: April 18, 2009
CAPWAP Access Controller DHCP Option
draft-ietf-capwap-dhc-ac-option-02
Status of this Memo Control And Provisioning of Wireless Access Points (CAPWAP)
Access Controller DHCP Option
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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 to which it is to connect. This document
DHCP options to be used by the CAPWAP protocol. describes the DHCP options to be used by the CAPWAP Protocol.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction ....................................................2
1.1. Conventions used in this document . . . . . . . . . . . . 3 1.1. Conventions Used in This Document ..........................2
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Terminology ................................................2
2. CAPWAP AC DHCPv4 Option . . . . . . . . . . . . . . . . . . . 4 2. CAPWAP AC DHCPv4 Option .........................................2
3. CAPWAP AC DHCPv6 Option . . . . . . . . . . . . . . . . . . . 5 3. CAPWAP AC DHCPv6 Option .........................................3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 4. IANA Considerations .............................................5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 5. Security Considerations .........................................5
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 6. Acknowledgments .................................................5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7. References ......................................................5
7.1. Normative References . . . . . . . . . . . . . . . . . . . 10 7.1. Normative References .......................................5
7.2. Informational References . . . . . . . . . . . . . . . . . 10 7.2. Informative References .....................................6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 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) [I-D.ietf-capwap-protocol-specification] allows a Wireless (CAPWAP) [RFC5415] allows a Wireless Termination Point (WTP) to use
Termination Point (WTP) to use DHCP to discover the Access DHCP to discover the Access Controllers (AC) to which it is to
Controllers (AC) it is to connect to. connect.
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 with which to establish a CAPWAP
with. One of these methods is through the DHCP protocol. This is connection. One of these methods is through the DHCP protocol. This
done through the CAPWAP AC DHCPv4 or CAPWAP AC DHCPv6 Option. is 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 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
1.2. Terminology 1.2. Terminology
This document uses terminology defined in [RFC3753], [RFC2131], This document uses terminology defined in [RFC3753], [RFC2131],
[RFC3315] and [I-D.ietf-capwap-protocol-specification]. [RFC3315], and [RFC5415].
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 ACs available
the WTP. to 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:
0 1 0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-code | option-length | | option-code | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ AC IPv4 Address + + AC IPv4 Address +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: OPTION_CAPWAP_AC_V4 (TBD) option-code: OPTION_CAPWAP_AC_V4 (138)
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 that 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 DHCPv4 client, acting on behalf of a CAPWAP WTP, MUST request the A DHCPv4 client, acting on behalf of a CAPWAP WTP, MUST request the
CAPWAP AC DHCPv4 Option in a Parameter Request List Option, as CAPWAP AC DHCPv4 Option in a Parameter Request List Option, as
described in [RFC2131] and [RFC2132]. described in [RFC2131] and [RFC2132].
A DHCPv4 server returns the CAPWAP AC Option to the client if the A DHCPv4 server returns the CAPWAP AC Option to the client if the
server policy is configured appropriately and the server is server policy is configured appropriately and the server is
configured with a list of CAPWAP AC addresses. configured with a list of CAPWAP AC addresses.
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 an AC.
CAPWAP protocol [I-D.ietf-capwap-protocol-specification] provides The CAPWAP Protocol [RFC5415] provides guidance on the WTP's
guidance on the WTP's discovery process. 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 ACs available
the WTP. to the WTP.
The DHCPv6 option for CAPWAP has the format shown in the following The DHCPv6 option for CAPWAP has the format shown in the following
figure: figure:
0 1 2 3 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 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 | | option-code | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| | | |
+ AC IPv6 Address + + AC IPv6 Address +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| .... | | .... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: OPTION_CAPWAP_AC_V6 (TBD) option-code: OPTION_CAPWAP_AC_V6 (52)
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 that 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 DHCPv6 client, acting on behalf of a CAPWAP WTP, MUST request the A DHCPv6 client, acting on behalf of a CAPWAP WTP, MUST request the
CAPWAP AC DHCPv6 Option in a Parameter Request List Option, as CAPWAP AC DHCPv6 Option in a Parameter Request List Option, as
described in [RFC3315]. described in [RFC3315].
A DHCPv6 server returns the CAPWAP AC Option to the client if the A DHCPv6 server returns the CAPWAP AC Option to the client if the
server policy is configured appropriately and the server is server policy is configured appropriately and the server is
configured with a list of CAPWAP AC addresses. configured with a list of CAPWAP AC addresses.
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 an AC.
CAPWAP protocol [I-D.ietf-capwap-protocol-specification] provides The CAPWAP Protocol [RFC5415] provides guidance on the WTP's
guidance on the WTP's discovery process. 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 Options has been
assigned by IANA: assigned by IANA:
Option Name Value Described in Option Name Value Described in
----------------------------------------------- -----------------------------------------------
OPTION_CAPWAP_AC_V4 TBD Section 2 OPTION_CAPWAP_AC_V4 138 Section 2
The following DHCPv6 option code for CAPWAP AC options MUST be The following DHCPv6 option code for CAPWAP AC Options has been
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 52 Section 3
5. Security Considerations 5. Security Considerations
The security considerations in [RFC2131], [RFC2132] and [RFC3315] The security considerations in [RFC2131], [RFC2132], and [RFC3315]
apply. If an adversary manages to modify the response from a DHCP 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 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 rogue CAPWAP AC, possibly one that then intercepts call requests or
denies service. CAPWAP's use of DTLS MUST be used to authenticate denies service. CAPWAP's use of Datagram Transport Layer Security
the CAPWAP peers in the establishment of the session. (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 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, in security sensitive nor origin authenticated. Therefore, in security sensitive
environments the options defined in this document SHOULD NOT be the environments, the options defined in this document SHOULD NOT be the
only methods used to determine which AC a WTP should connect to. The only methods used to determine to which AC a WTP should connect. The
CAPWAP protocol [I-D.ietf-capwap-protocol-specification] defines CAPWAP protocol [RFC5415] defines other AC discovery procedures a WTP
other AC discovery procedures a WTP MAY utilize. MAY utilize.
6. Acknowledgments 6. Acknowledgments
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
skipping to change at page 10, line 22 skipping to change at page 6, line 12
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", [RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, March 1997. RFC 2131, March 1997.
[RFC2132] 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.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003. IPv6 (DHCPv6)", RFC 3315, July 2003.
[I-D.ietf-capwap-protocol-specification] [RFC5415] Montemurro, M., Stanley, D., and P. Calhoun, "CAPWAP
Montemurro, M., Stanley, D., and P. Calhoun, "CAPWAP Protocol Specification", RFC 5415, March 2009.
Protocol Specification",
draft-ietf-capwap-protocol-specification-13 (work in
progress), September 2008.
7.2. Informational References 7.2. Informative References
[RFC3753] 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: +1 408-902-3240 Phone: +1 408-902-3240
Email: pcalhoun@cisco.com EMail: pcalhoun@cisco.com
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