RFC 5417
Control And Provisioning of Wireless Access Points (CAPWAP) Access Controller DHCP Option
RFC 5417: CAPWAP Access Controller DHCP Option 🎀
Okay bestie, let's talk about this one! ✨ This is RFC 5417, a Standards Track doc written by P. Calhoun (Cisco Systems, Inc.), dated March 2009. It doesn't obsolete or update anything, so it's a fresh start, no cap 💅. It's all about how a wireless access point can use DHCP to find the controllers it's supposed to connect to 📡. The title is Control And Provisioning of Wireless Access Points (CAPWAP) Access Controller DHCP Option 🦋.
Status of This Memo ✨
Okay so this is an Internet standards track protocol for the Internet community, and it's asking for discussion and suggestions for improvements 🫶. If you want the current standardization state and status, check the "Internet Official Protocol Standards" (STD 1) 📚. Distribution of this memo is unlimited, so share it with everyone 💖.
Copyright Notice 🌈
Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved 💜.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, because they spell out your rights and restrictions 🙈.
This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The people controlling the copyright in some of that material may not have granted the IETF Trust the right to allow modifications outside the IETF Standards Process. Without an adequate license from them, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English 🍓. Translation: be careful with the copyright drama 😭.
Abstract 🧚
The Control And Provisioning of Wireless Access Points Protocol lets a Wireless Termination Point use DHCP to discover the Access Controllers it's meant to connect to 💅. This doc describes the DHCP options that the CAPWAP Protocol uses 🔥.
Table of Contents 🌸
1. Introduction ....................................................2
1.1. Conventions Used in This Document ..........................2
1.2. Terminology ................................................2
2. CAPWAP AC DHCPv4 Option .........................................2
3. CAPWAP AC DHCPv6 Option .........................................3
4. IANA Considerations .............................................5
5. Security Considerations .........................................5
6. Acknowledgments .................................................5
7. References ......................................................5
7.1. Normative References .......................................5
7.2. Informative References .....................................61. Introduction 💖
Okay so the Control And Provisioning of Wireless Access Points Protocol (CAPWAP) [RFC5415] lets a Wireless Termination Point (WTP) use DHCP to discover the Access Controllers (AC) it's supposed to connect to 🎀.
Before the CAPWAP Discovery process even starts, the WTP has a bunch of ways to figure out which AC to connect with, and DHCP is one of them 🦋. You'd use the CAPWAP AC DHCPv4 or CAPWAP AC DHCPv6 Option to do it 👑.
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], [RFC2131], [RFC3315], and [RFC5415] 🧚.
2. CAPWAP AC DHCPv4 Option 🦋
This section defines a DHCPv4 option that carries a list of 32-bit (binary) IPv4 addresses for one or more CAPWAP ACs the WTP can use 💜.
The DHCPv4 option for CAPWAP looks like this 👇:
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 (138) 🍓
option-length: The length of the 'options' field in octets. It MUST be a multiple of four (4) 🔥.
AC IPv4 Address: The IPv4 address of a CAPWAP AC that the WTP may use. The ACs are listed in order of preference for the WTP 🫶.
A DHCPv4 client, acting on behalf of a CAPWAP WTP, MUST request the CAPWAP AC DHCPv4 Option in a Parameter Request List Option, as described in [RFC2131] and [RFC2132] 💅.
A DHCPv4 server returns the CAPWAP AC Option to the client if the server policy is configured appropriately and the server has a list of CAPWAP AC addresses configured 🎀.
A CAPWAP WTP acting as a DHCPv4 client that receives the CAPWAP AC DHCPv4 Option MAY use the (list of) IP address(es) to locate an AC 🦋. The CAPWAP Protocol [RFC5415] gives 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 it received from the DHCPv4 server 💖.
3. CAPWAP AC DHCPv6 Option 👑
This section defines a DHCPv6 option that carries a list of 128-bit (binary) IPv6 addresses for one or more CAPWAP ACs the WTP can use 🌸.
The DHCPv6 option for CAPWAP looks like this 👇:
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 (52) 🍓
option-length: The length of the 'options' field in octets. It MUST be a multiple of sixteen (16) 🔥.
AC IPv6 Address: The IPv6 address of a CAPWAP AC that the WTP may use. The ACs are listed in order of preference for the WTP 🫶.
A DHCPv6 client, acting on behalf of a CAPWAP WTP, MUST request the CAPWAP AC DHCPv6 Option in a Parameter Request List Option, as described in [RFC3315] 💅.
A DHCPv6 server returns the CAPWAP AC Option to the client if the server policy is configured appropriately and the server has a list of CAPWAP AC addresses configured 🎀.
A CAPWAP WTP acting as a DHCPv6 client that receives the CAPWAP AC DHCPv6 Option MAY use the (list of) IP address(es) to locate an AC 🦋. The CAPWAP Protocol [RFC5415] gives 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 it received from the DHCPv6 server 💖.
4. IANA Considerations 🌈
IANA has assigned the following DHCPv4 option code for CAPWAP AC Options:
Option Name Value Described in
-----------------------------------------------
OPTION_CAPWAP_AC_V4 138 Section 2IANA has also assigned the following DHCPv6 option code for CAPWAP AC Options:
Option Name Value Described in
------------------------------------------------
OPTION_CAPWAP_AC_V6 52 Section 35. Security Considerations 🙈
Okay bestie, this part is SERIOUS 😭. The security considerations in [RFC2131], [RFC2132], and [RFC3315] apply. If an adversary manages to change the response from a DHCP server or sneak in their own response, a WTP could be tricked into contacting a rogue CAPWAP AC 💀. That rogue AC might then intercept call requests or deny service 🔥.
CAPWAP's use of Datagram Transport Layer Security (DTLS) MUST be used to authenticate the CAPWAP peers when the session is established 🔐✨.
In most networks, the DHCP exchange that delivers these options, which happens before network access authentication, is neither integrity protected nor origin authenticated 😭. So in security-sensitive environments, the options defined in this document SHOULD NOT be the only methods used to decide which AC a WTP should connect to 🫶. The CAPWAP protocol [RFC5415] defines other AC discovery procedures that a WTP MAY use 💅.
6. Acknowledgments 💜
The following individuals are acknowledged for their contributions to this protocol specification: Ralph Droms and Margaret Wasserman 🦋.
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.
[RFC5415] Montemurro, M., Stanley, D., and P. Calhoun, "CAPWAP
Protocol Specification", RFC 5415, March 2009.7.2. Informative References 🧚
[RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology",
RFC 3753, June 2004.Author's Address 💅
Pat R. Calhoun Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134
Phone: +1 408-902-3240 EMail: pcalhoun@cisco.com
📦 where this page comes from
- ietf: rfc5417 2009-03
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms