CAPWAP Working Group H. Wen
Internet-Draft Alcatel Shanghai Bell
Expires: April 14, 2009 S. Jain
Alcatel-Lucent
October 15, 2008
CAPWAP Station IP Address
draft-wen-capwap-station-ip-address-00.txt
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Abstract
In Control And Provisioning of Wireless Access Points Protocol, the
Access Controller controls whether Wireless Termination Point should
forward the traffic for some specified station. This document defines
a mew messages elements, IEEE Station IP Address, which are used for
better control of station's access in local-MAC mode of CAPWAP.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions used in this document . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. CAPWAP Station IP Address. . . . . . . . . . . . . . . . . . . 4
3. Type Value Consideration . . . . . . . . . . . . . . . . . . 5
4. IANA Consideration . . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7
Intellectual Property and Copyright Statements . . . . . . . . . . 8
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1. Introduction
The Control And Provisioning of Wireless Access Points Protocol
(CAPWAP) [I-D.ietf-capwap-protocol-specification] controls a Wireless
Termination Point (WTP) whether it should forward the traffic for a
station via the Access Controllers (AC) by the following message
elements: Add Station, Add MAC ACL Entry, Add Static MAC ACL Entry.
In order to avoid IP address anti-spoofing, for any authorized
station, the WTP may be informed about the binding between the
physical address and the authorized IP address. The AC should notify
the binding to the WTP, which is done using CAPWAP Station IP Address
message element.
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 [I-D.ietf-capwap-protocol-
specification].
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2. CAPWAP Station IP Address
The CAPWAP Station IP message element accompanies the Add Station
message element, and is used to deliver the IP address of the
station from the AC to the WTP. This message element may be present
in the station configuration request and used to control station's
access to the network avoid IP address spoofing.
The latest CAPWAP Station IP Adress message element overrides any
previously received message elements.
The Station IP Address message element 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Version| Rsvd | IP address ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: Message_Element_Station_IP_Address (TBD)
Version: 4-bit version field. When Version = 4, it means IPv4
address is used; When Version = 6, it means that IPv6 address is
used.
Rsvd: The 24-bit field is reserved for future use. All
implementations MUST set this field to zero. Receivers MUST
ignore all bits not defined for the version of the protocol.
IP Address: The length of this field is either 4-bye or 16-byte, it
depends on the value of Version field. When the version filed
indicates that it's in IPv4 environment, IPv4 address allocated to
the station is filled in this field. When the version field
indicates it's in IPv6 environment, IPv6 address is used.
Usage:
This message element is used in Station Configuration Request as an
optional message element when local-MAC mode is deployed.
When this message element is used, it must directly follow Add
Station message element. The purpose of this message is to enable WTP
to implement the function of IP address anti-spoofing.
When the WTP receives Station Configuration Request, its operations
related to this message element are as follows:
(1) When the WTP finds this message element following an Add Station
, it creates the entry of <IP address, MAC address> for the IP
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address anti-spoofing table from the two message elements.
(2) If there is no CAPWAP Station IP Address message element
directly followed the Add Station, this means that IP address
anti-spoofing rule doesn't be applied on this station.
When IP address anti-spoofing is deployed in the centralized WLAN
system, once the WTP receives the frame from a station, it will check
the frame against the <IP address, MAC address> table before
forwarding it:
If (station's <MAC address, IP addres> present in the table)
Pass the frame
Else
Drop the frame
3. Type Value Consideration
The following Message Element type value for CAPWAP Station IP
Address message element MUST be assigned by CAPWAP working group:
Message Element Value
-----------------------------------------------------------
CAPWAP Station IP Address Station_IP_Address
4. IANA Consideration
This document has no actions for IANA.
5. Security Considerations
There is no more security issue introduced by this message element.
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6. Acknowledgements
The following individuals are acknowledged for their contributions to
this draft: Songwei MA.
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.
[I-D.ietf-capwap-protocol-specification]
Calhoun, P., "CAPWAP Protocol Specification",
draft-ietf-capwap-protocol-specification-13 (work in
progress), September 19, 2008.
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Author's Address
Haibo WEN
Alcatel Shanghai Bell Co., Ltd.
388#, NingQiao Road, Pudong Jinqiao
Shanghai 201206 P.R. China
Phone: +86 (21) 5854-1240, extension. 9273
Email: Haibo.WEN@alcatel-sbell.com.cn
Sudhanshu JAIN
Alcatel-Lucent
755 Ravendale Dr,
Mountain View, CA 94043
Phone: +1 650 623 3329
Email: Sudhanshu.jain@alcatel-lucent.com
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