[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-zhou-capwap-objectives) 00 01 02 03 04 RFC 4564

Network Working Group                               S. Govindan (Editor)
Internet-Draft                                                 Panasonic
Expires: October 16, 2005                                        ZH. Yao
                                                                  Huawei
                                                                WH. Zhou
                                                            China Mobile
                                                                 L. Yang
                                                                   Intel
                                                                H. Cheng
                                                               Panasonic
                                                          April 14, 2005


   Objectives for Control and Provisioning of Wireless Access Points
                                (CAPWAP)
                  draft-ietf-capwap-objectives-02.txt

Status of this Memo

   This document is an Internet-Draft and is subject to all provisions
   of Section 3 of RFC 3667.  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 become aware will be disclosed, in accordance with
   RFC 3668.

   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 October 16, 2005.

Copyright Notice

   Copyright (C) The Internet Society (2005).




Govindan (Editor), et al.    Expires October 16, 2005           [Page 1]

Internet-Draft              CAPWAP Objectives                 April 2005


Abstract

   This document presents objectives for an interoperable protocol for
   the Control and Provisioning of Wireless Access Points (CAPWAP).  The
   document aims to establish a set of focused requirements for the
   development and evaluation of a CAPWAP protocol.  The objectives
   address Architecture, Operation, Security and Network Operator
   Requirements that are necessary to enable interoperability among
   wireless local area network (WLAN) devices of alternative designs.










































Govindan (Editor), et al.    Expires October 16, 2005           [Page 2]

Internet-Draft              CAPWAP Objectives                 April 2005


Table of Contents

   1.   Requirements notation  . . . . . . . . . . . . . . . . . . .   4
   2.   Terminology  . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.   Introduction . . . . . . . . . . . . . . . . . . . . . . . .   6
   4.   Objectives Overview  . . . . . . . . . . . . . . . . . . . .   7
   5.   Objectives . . . . . . . . . . . . . . . . . . . . . . . . .   8
     5.1  Mandatory and Accepted Objectives  . . . . . . . . . . . .   8
       5.1.1  Logical Groups . . . . . . . . . . . . . . . . . . . .   8
       5.1.2  Support for Traffic Separation . . . . . . . . . . . .   9
       5.1.3  Wireless Terminal Transparency . . . . . . . . . . . .  10
       5.1.4  Configuration Consistency  . . . . . . . . . . . . . .  11
       5.1.5  Firmware Trigger . . . . . . . . . . . . . . . . . . .  12
       5.1.6  Monitoring and Exchange of System-wide Resource
              State  . . . . . . . . . . . . . . . . . . . . . . . .  12
       5.1.7  Resource Control Objective . . . . . . . . . . . . . .  13
       5.1.8  CAPWAP Protocol Security . . . . . . . . . . . . . . .  15
       5.1.9  System-wide Security . . . . . . . . . . . . . . . . .  16
       5.1.10   IEEE 802.11i Considerations  . . . . . . . . . . . .  17
       5.1.11   Interoperability Objective . . . . . . . . . . . . .  18
       5.1.12   Protocol Specifications  . . . . . . . . . . . . . .  20
       5.1.13   Vendor Independence  . . . . . . . . . . . . . . . .  20
       5.1.14   Vendor Flexibility . . . . . . . . . . . . . . . . .  21
     5.2  Desirable Objectives . . . . . . . . . . . . . . . . . . .  21
       5.2.1  Multiple Authentication Mechanisms . . . . . . . . . .  22
       5.2.2  Support for Future Wireless Technologies . . . . . . .  22
       5.2.3  Support for New IEEE Requirements  . . . . . . . . . .  23
       5.2.4  Interconnection Objective  . . . . . . . . . . . . . .  24
       5.2.5  Access Control . . . . . . . . . . . . . . . . . . . .  25
     5.3  Rejected Objectives  . . . . . . . . . . . . . . . . . . .  26
       5.3.1  Support for Non-CAPWAP WTPs  . . . . . . . . . . . . .  26
       5.3.2  Technical Specifications . . . . . . . . . . . . . . .  26
     5.4  Operator Requirements  . . . . . . . . . . . . . . . . . .  27
       5.4.1  AP Fast Handoff  . . . . . . . . . . . . . . . . . . .  27
   6.   Summary and Conclusion . . . . . . . . . . . . . . . . . . .  28
   7.   Security Considerations  . . . . . . . . . . . . . . . . . .  29
   8.   Acknowledgements . . . . . . . . . . . . . . . . . . . . . .  30
   9.   References . . . . . . . . . . . . . . . . . . . . . . . . .  30
        Authors' Addresses . . . . . . . . . . . . . . . . . . . . .  30
        Intellectual Property and Copyright Statements . . . . . . .  32











Govindan (Editor), et al.    Expires October 16, 2005           [Page 3]

Internet-Draft              CAPWAP Objectives                 April 2005


1.  Requirements notation

   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 [RFC2119].














































Govindan (Editor), et al.    Expires October 16, 2005           [Page 4]

Internet-Draft              CAPWAP Objectives                 April 2005


2.  Terminology

   This document follows the terminologies of [I-D.ietf-capwap-arch].
   Additionally, the following terms are defined;

   Switching Segment: Those aspects of a centralized WLAN that primarily
   deal with switching or routing of control and data information
   between Wireless Termination Points (WTPs) and the WLAN controller.

   Wireless Medium Segment: Those aspects of a centralized WLAN that
   primarily deal with the wireless interface between WTPs and wireless
   terminals.  The Wireless Medium Segment is specific to layer 2
   wireless technology, such as IEEE 802.11.

   CAPWAP Framework: A term that covers the local-MAC and split-MAC
   designs of the Centralized WLAN Architecture.  Standardization
   efforts are focussed on these designs.

   CAPWAP Protocol: The protocol between WLAN controller and WTPs in the
   CAPWAP framework.  It facilitates control, management and
   provisioning of WTPs in an interoperable manner.






























Govindan (Editor), et al.    Expires October 16, 2005           [Page 5]

Internet-Draft              CAPWAP Objectives                 April 2005


3.  Introduction

   The growth in large-scale wireless local area network (WLAN)
   deployments has brought to focus a number of technical challenges.
   Among them is the complexity of managing large numbers of wireless
   termination points (WTPs), which is further exacerbated by variations
   in their design.  Another challenge is the maintenance of consistent
   configurations among the numerous WTPs of a system.  The dynamic
   nature of the wireless medium is also a concern together with WLAN
   security.  The challenges affecting large-scale WLAN deployments have
   been highlighted in [I-D.ietf-capwap-problem-statement].

   Many vendors have addressed these challenges by developing new
   architectures and solutions.  A survey of the various developments
   was conducted to better understand the context of these challenges.
   This survey is a first step towards designing interoperability among
   the solutions.  The Architecture Taxonomy [I-D.ietf-capwap-arch] is a
   result of this survey in which major WLAN architecture families are
   classified.  Broadly, these are the autonomous, centralized WLAN and
   distributed mesh architectures.

   The Architecture Taxonomy identified that the current majority of
   large-scale deployments follow the centralized WLAN architecture in
   which portions of the wireless medium access control (MAC) operations
   are centralized in a WLAN controller.  This centralized WLAN
   architecture is further classified into remote-MAC, split-MAC and
   local-MAC designs.  Each differs in the degree of separation of
   wireless MAC layer capabilities between WTPs and WLAN controller.

   This document puts forward critical objectives for achieving
   interoperability in the CAPWAP framework.  It presents requirements
   that address the challenges of controling and provisioning large-
   scale WLAN deployments.  The realization of these objectives in a
   CAPWAP protocol will ensure that WLAN equipment of major design types
   may be integrally deployed and managed.
















Govindan (Editor), et al.    Expires October 16, 2005           [Page 6]

Internet-Draft              CAPWAP Objectives                 April 2005


4.  Objectives Overview

   The objectives for CAPWAP have been broadly classified to address
   architecture, operation and security requirements of managing large-
   scale WLAN deployments.

   Architecture objectives deal with system level aspects of the CAPWAP
   protocol.  They address issues of protocol extensibility, diversity
   in network deployments and architecture designs and differences in
   transport technologies.

   Operational objectives address the control and management features of
   the CAPWAP protocol.  They deal with operations relating to WLAN
   monitoring, resource management, QoS and access control.

   Security objectives address potential threats to WLANs and their
   containment.  In the CAPWAP context, security requirements cover both
   the protocol between WLAN controller and WTPs and also the WLAN
   system as a whole.

   Additionally, a general classification is used for objectives
   relating to the overall impact of the CAPWAP protocol specifications.





























Govindan (Editor), et al.    Expires October 16, 2005           [Page 7]

Internet-Draft              CAPWAP Objectives                 April 2005


5.  Objectives

   The objectives described in this document have been prioritized based
   on their immediate significance in the development and evaluation of
   a control and provisioning protocol for large-scale WLAN deployments.
   Additionally, one category is provided for requirements gathered from
   network service operators.  These are specific need that arise from
   operators' experiencese in deploying and managing large-scale WLANs.
   The priorities are;

   i.  Mandatory and Accepted Objectives
   ii.  Desirable Objectives
   iii.  Rejected Objectives
   iv.  Operator Requirements

   The priorities have been assigned to individual objectives in
   accordance with working group discussions.

5.1  Mandatory and Accepted Objectives

   Objectives prioritized as Mandatory and Accepted have been deemed
   crucial for the control and provisioning of WTPs.  They directly
   address the challenges of large-scale WLAN deployments and must be
   realized by a CAPWAP protocol.

5.1.1  Logical Groups

   Classification: Architecture

   Description:

   Large WLAN deployments are complex and expensive.  Furthermore,
   enterprises deploying such networks are under pressure to improve the
   efficiency of their expenditures.

   Shared WLAN deployments, where a single physical WLAN infrastructure
   supports a number of logical networks, are increasingly used to
   address these two issues of large-scale WLANs.  These are popular as
   they allow deployment and management costs to be spread across
   businesses.

   In traditional WLANs, each physical WTP represents one complete
   subset of a larger WLAN system.  Shared WLANs differ in that each
   physical WTP represents a number of logical subsets of possibly a
   number of larger WLAN systems.  Each logical division of a physical
   WTP is referred to as a logical group.  For example, each BSSID of a
   physical WTP can be construed to be a logical group.  So WLANs are
   managed in terms of logical groups instead of physical WTPs.  Virtual



Govindan (Editor), et al.    Expires October 16, 2005           [Page 8]

Internet-Draft              CAPWAP Objectives                 April 2005


   APs are examples of logical groups.

   Protocol Requirement:

   WLAN deployment trends require the CAPWAP protocol to be capable of
   controlling and managing physical WTPs in terms of logical groups.

   Motivation and Protocol Benefits:

   Commercial realities necessitate that WLANs be manageable in terms of
   its logical groups.  This allows separation of logical services and
   underlying infrastructure management.  A protocol that realizes this
   need ensures simlper and cost effective WLANs, which directly address
   the requirements of network service operators.

   Relation to Problem Statement:

   This objective addresses the problem of management complexity in
   terms of costs.  Cost complexity is reduced by sharing WLAN
   deployments.  Consequently, deployment and management cost-
   efficiencies are realized.

5.1.2  Support for Traffic Separation

   Classification: Operations

   Description:

   The centralized WLAN architecture simplifies complexity associated
   with large-scale deployments by consolidating portions of wireless
   MAC functionality at a central WLAN controller and distributing the
   remaining across WTPs.  As a result, WTPs and WLAN controller
   exchange control and data information between them.  This objective
   states that control and data aspects of the exchanges be mutually
   separated for further simplicity.  This will allow solutions for each
   type of exchange to be independently optimized.

   Furthermore, in the context of shared WLAN deployments, the mutual
   separation of control and data also addresses security concerns.  In
   particular, given the likelihood of different logical groups being
   managed by different administrators, separation of control and data
   is a first step towards individually containing and securing the
   logical groups.

   It is also important to ensure that traffic from each logical group
   be mutually separated to maintain the integrity and independence of
   the logical groups.




Govindan (Editor), et al.    Expires October 16, 2005           [Page 9]

Internet-Draft              CAPWAP Objectives                 April 2005


   Protocol Requirement:

   In order to maintain the separation of control and data traffic, the
   CAPWAP protocol is required to define control messages such that they
   do not involve piggybacking or other combination with data traffic.

   Motivation and Protocol Benefits:

   The aim of separating data and control aspects of the protocol is to
   simplify the protocol.  It also allows for the flexibility of
   addressing each type of traffic in the most appropriate manner.

   Furthermore, such separation provides for the separation of data and
   control paths.  This will help remotely located WTPs to handle data
   traffic in alternative ways without the need for forwarding them
   across a wide network to the WLAN controller.

   Separation of WTP control and data also aids in the secure
   realization of shared WLAN deployments.

   Relation to Problem Statement:

   Broadly, this objective relates to the challenge of managing
   complexity in large-scale WLANs.  The requirement for traffic
   separation simplifies control as this is separated from the task of
   data transport.

5.1.3  Wireless Terminal Transparency

   Classification: Operations

   Description:

   The CAPWAP protocol is applicable between a centralized WLAN
   controller and a number of WTPs, i.e. it affects only the switching
   segment of the centralized WLAN architecture.  Its operations should
   therefore be independent of the wireless terminal.  Wireless
   terminals should not be required to be aware of the existence of the
   CAPWAP protocol.

   Protocol Requirement:

   Wireless terminals should not be required to recognize or be aware of
   the CAPWAP protocol.

   Motivation and Protocol Benefits:

   IEEE 802.11 based wireless terminals are mature and widely available.



Govindan (Editor), et al.    Expires October 16, 2005          [Page 10]

Internet-Draft              CAPWAP Objectives                 April 2005


   It would be beneficial for CAPWAP not to impose new requirements on
   these wireless terminals.  In effect, this requirement ensures that
   the setup cost of the protocol is reduced as the numerous existing
   wireless terminals need not be altered.

   Relation to Problem Statement:

   The Problem Statement highlights the challenges faced by large WLANs
   consisting of many WTPs.  It does not refer to the operations of
   wireless terminals and this objective emphasizes the independence.

5.1.4  Configuration Consistency

   Classification: Operations

   Description:

   WLANs in the CAPWAP framework contain numerous WTPs, each of which
   need to be configured and managed in a consistent manner.  This is
   possible by providing the centralized WLAN controller with regular
   updates on the state of their operations.  The centralized WLAN
   controller can in turn apply information from the regular updates to
   consistently configure the WTPs.

   Protocol Requirement:

   The CAPWAP protocol must allow for regular exchanges of state
   information between WTPs and WLAN controller.  Examples of state
   information include WTP processing load and memory utilization.

   Motivation and Protocol Benefits:

   A protocol that has access to regular state information can in turn
   use this to enhance WLAN performance.  The CAPWAP protocol will be
   better equipped to address configuration related problems with the
   state information.  So with greater state information, control and
   management operations can be improved.

   Relation to Problem Statement:

   One of the major challenges described in the Problem Statement is
   that of maintaining consistent configuration across the numerous WTPs
   of a WLAN.  This objective fundamentally addresses this challenge by
   providing relevant state information based on which configurations
   can be appropriately maintained.






Govindan (Editor), et al.    Expires October 16, 2005          [Page 11]

Internet-Draft              CAPWAP Objectives                 April 2005


5.1.5  Firmware Trigger

   Classification: Operations

   Description:

   One specific aspect of configuration consistency is the firmware used
   by various WTPs.  The scale of large WLANs introduces possibilities
   for variations in the firmware used among WTPs.  This objective
   highlights the need for the CAPWAP protocol to trigger the delivery
   of appropriate versions of firmware to WTPs.  The actual delivery of
   firmware need not be inclusive to the prtoocol.

   Protocol Requirement:

   The CAPWAP protocol must support a trigger for delivery of firmware
   updates.

   Motivation and Protocol Benefits:

   The CAPWAP protocol interfaces many WTPs to a centralized WLAN
   controller.  Firmware distribution allows these interfaces to be
   appropriately equivalent.  This in turn results in consistent
   configuration and simplified management.  So the protocol benefits by
   including triggers for the distribution of firmware updates.

   Relation to Problem Statement:

   Inconsistencies in the configuration of WTPs has been identified as a
   major challenge for large-scale WTPs.  This objectives helps overcome
   the challenge by providing for a way for the protocol to initiate
   delivery of equivalent versions of firmware to all WTPs.

5.1.6  Monitoring and Exchange of System-wide Resource State

   Classification: Operations

   Description:

   The centralized WLAN architecture is made up of a switching segment
   and wireless medium segment.  In the switching segment, network
   congestion, WTP status and firmware information have to be monitored.
   In the wireless medium segment, the dynamic nature of the medium
   itself has to be monitored.  Overall, there are also various
   statistics need to be considered for efficient WLAN operation.

   The CAPWAP protocol should be capable of monitoring the various
   information sources and deliver the resulting information to the



Govindan (Editor), et al.    Expires October 16, 2005          [Page 12]

Internet-Draft              CAPWAP Objectives                 April 2005


   relevant WLAN devices - either WTPs or WLAN controller.  Moreover,
   given the relationship among information sources, the CAPWAP protocol
   should combine state information from them.  For example, statistics
   information and status signals from WTPs may be merged before being
   exchanged.

   Examples of statistics information that the CAPWAP protocol should
   monitor and exchange include; congestion state, interference levels,
   loss rates and various delay factors.

   Protocol Requirement:

   The CAPWAP protocol must allow for the exchange of statistics,
   congestion and other WLAN state information.

   Motivation and Protocol Benefits:

   The effectivness of a protocol is based on the relevance of
   information on which it operates.  This requirement for resource
   monitoring and exchange can provide the appropriate information to
   the CAPWAP protocol.

   Relation to Problem Statement:

   The Problem Statement highlights the challenge of dealing with large
   numbers of WTPs and the dynamic nature of the wireless medium.
   Information on the state of WTPs and the medium is important to deal
   with them effectively.  So this objective relates to the problem of
   managing consistency in large WLANs.

5.1.7  Resource Control Objective

   Classification: Operations

   Description:

   Integral to the success of any wireless network system is the
   performance and quality it can offer its subscribers.  Since CAPWAP
   based WLANs combine a switching segment and a wireless medium
   segment, performance and quality need to be coordinated across both
   of these segments.  So QoS performance must be enforced system-wide.

   This objective highlights QoS over the entire WLAN system which
   includes the switching segment and the wireless medium segment.
   Given the fundamental differences between the two, it is likely that
   there are alternate QoS mechanisms between WTPs and wireless service
   subscribers and between WTPs and WLAN controllers.  For instance, the
   former will be based on IEEE 802.11e while the latter will be an



Govindan (Editor), et al.    Expires October 16, 2005          [Page 13]

Internet-Draft              CAPWAP Objectives                 April 2005


   alternative.  So resources need to be adjusted in a coordinated
   fashion over both segments.  The CAPWAP protocol should ensure that
   these adjustments are appropriately exchanged between WLAN
   controllers and WTPs.

   In addition to IEEE 802.11e, there are a number of other IEEE Task
   Groups that may affect network resources.  These include IEEE TGk,
   TGu and TGv, which are currently under progress.  CAPWAP should
   therefore not be restricted to IEEE 802.11e based mapping.

   Protocol Requirement:

   The CAPWAP protocol must maintain IEEE 802.11e QoS mappings across
   the switching and wireless medium segments.

   Motivation and Protocol Benefits:

   A protocol that addresses QoS aspects of WLAN systems will deliver
   high performance thereby being beneficial for subscribers and for
   resource utilization efficiency.  Since CAPWAP deals with WTPs
   directly and with the wireless medium indirectly, both of these must
   be considered for performance.

   For the wireless medium segment, QoS aspects in the protocol enable
   high quality communications within the domain of a WLAN controller.
   Since each domain generally covers an enterprise or a group of
   service providers, such protocol performance has wide-ranging
   effects.

   Within the switching segment of CAPWAP, a QoS-enabled protocol
   minimizes the adverse effects of dynamic traffic characteristics so
   as to ensure system-wide performance.

   Relation to Problem Statement:

   QoS control is critical to large WLANs and relates to a number of
   aspects.  In particular, this objective can help address the problem
   of managing dynamic conditions of the wireless medium.

   Furthermore, traffic characteristics in large scale WLANs are
   constantly varying.  So network utilization becomes inefficient and
   user experience is unpredictable.

   The interaction and coordination between the two aspects of system-
   wide QoS is therefore critical for performance.






Govindan (Editor), et al.    Expires October 16, 2005          [Page 14]

Internet-Draft              CAPWAP Objectives                 April 2005


5.1.8  CAPWAP Protocol Security

   Classification: Security

   Description:

   This objective addresses the security of the CAPWAP protocol.

   The CAPWAP protocol must first provide for the participating entities
   - WLAN controller and WTPs - to be mutually authenticated.  This is
   to ensure that rogue WTPs do not breach legitimate WLAN systems.  For
   example, WTPs may need to regularly renew their authentication state
   with the WLAN controller.

   Once WTPs and WLAN controller have been mutually authenticated,
   information exchanges between them must be secured against various
   security threats.  This should cover illegitimate modifications to
   protocol exchanges, eavesdropping and DoS attacks, among other
   potential compromises.  So the protocol must be provide
   confidentiality, integrity and authenticity for those exchanges.

   As a result of realizing this objective it should not be possible for
   individual WTP breaches to affect the security of the WLAN as a
   whole.  So WTP mis-use will be protected against.

   Additionally, the key establishment protocol for authentication and
   securing CAPWAP exchanges must be designed to minimize the
   possibility of future compromises after the keys are established.

   While mutual authentication is necessary for CAPWAP, the protocol
   should not prevent the use of asymmetric, non-mutual authentication.
   The security considerations of such asymmetric authentication are
   described in the Security Considerations section.

   Protocol Requirement:

   The CAPWAP protocol must support mutual authentication of WTPs and
   the centralized controller.  It must also ensure that information
   exchanges between them are secured.

   Motivation and Protocol Benefits:

   WLANs are increasingly deployed in critical aspects of enterprise and
   consumer networks.  In these contexts, protocol security is crucial
   to assure the privacy and integrity expected from network
   administrators and end-users.  So securing the CAPWAP protocol has
   direct benefits in addressing these concerns.




Govindan (Editor), et al.    Expires October 16, 2005          [Page 15]

Internet-Draft              CAPWAP Objectives                 April 2005


   Relation to Problem Statement:

   Security problems in large-scale WLANs are detailed in the Problem
   Statement.  These include complications arising from rogue WTPs and
   compromised interfaces between WTPs and WLAN controller.  The
   requirement for protocol security addresses these problems and
   highlights the importance of protecting against them.

5.1.9  System-wide Security

   Classification: Security

   Description:

   The emphasis of this objective is on the security threats external to
   the centralized CAPWAP segment of a WLAN system.  The focus is
   therefore on rogue wireless clients and other illegitimate wireless
   interferences.  There are a number of specific external threats that
   need to be addressed within the CAPWAP framework.

   i.  PMK Sharing

   One aspect of this objective relates to recent discussions on PMK
   sharing in the CAPWAP framework.  This objective highlights the need
   to prevent exploitation of this ambiguity by rogue wireless clients.
   It is to ensure that any ambiguities arising from the CAPWAP
   framework are not cause for security breaches.

   Protocol Requirement:

   The design of the CAPWAP protocol should not allow for any
   compromises to the WLAN system by external entities.

   Motivation and Protocol Benefits:

   The external threats to the centralized WLAN architecture become
   increasingly crucial given the low cost of wireless clients.  Since
   it is relatively inexpensive for rogue individuals to mount attacks,
   it is important that WLAN systems are protected against them.
   Adequate mechanisms to thwart such external threats will be of
   tremendous benefit to the WLAN systems controlled and managed with
   the CAPWAP protocol.

   Relation to Problem Statement:

   This objective is based on the security needs highlighted in the
   Problem Statement.  Specifically, the Problem Statement discusses the
   effects of the shared wireless medium.  This represents the external



Govindan (Editor), et al.    Expires October 16, 2005          [Page 16]

Internet-Draft              CAPWAP Objectives                 April 2005


   aspects of the CAPWAP framework from which certain threats can arise.
   The system-wide security objective addresses such threats in relation
   to the Problem Statement.

5.1.10  IEEE 802.11i Considerations

   Classification: Operations

   Description:

   The CAPWAP protocol must support authentication in the centralized
   WLAN architecture in which the authenticator and encryption points
   can be located on distinct entities, i.e.  WLAN controller or WTP.
   The Architecture Taxonomy illustrates a number of variants, in both
   local-MAC and split-MAC designs, in which the authenticator is
   located at the WLAN controller and the encryption points are at the
   WTPs.  The CAPWAP protocol must be applicable to these variants and
   allow authentication mechanisms and their consistituent processes to
   be operable in these cases.

   An important issue to consider in this case is the exchange of key
   information when authenticator and encryption points are located on
   distinct entities.  For example, consider the case where IEEE 802.11i
   is used in a WLAN in which the WLAN controller realizes the
   authenticator, some WTPs realize encryption (possibly local-MAC WTPs)
   and other WTPs rely on the WLAN controller for encryption (possibly
   split-MAC WTPs).

   Here, CAPWAP will first need to identify the location of the
   authenticator and encryption points between each WLAN controller-WTP
   pair.  This will likely be part of the initial WTP configuration.
   Subsequently, the WTPs which realize encryption will need CAPWAP to
   exchange key information with the authenticator at the WLAN
   controller.  For the WTPs which do not realize encryption, CAPWAP
   need to adapt its control to bypass the key exchange phase.

   Clearly, the centralized WLAN architecture presents a different
   platform for authentication mechanisms compared to legacy WLANs in
   which a WTP realized both authenticator and encryption roles.  So
   this objective highlights the need for CAPWAP to support
   authentication and key management in the centralized WLAN
   architecture.

   Protocol Requirement:

   The CAPWAP protocol must determine the exact structure of the
   centralized WLAN architecture in which authentication needs to be
   supported, i.e. the location of major authentication components.



Govindan (Editor), et al.    Expires October 16, 2005          [Page 17]

Internet-Draft              CAPWAP Objectives                 April 2005


   This may be achieved during WTP initialization where major
   capabilities are distinguished.

   The protocol must allow for the exchange of key information when
   authenticator and encryption roles are located in distinct entities.

   Motivation and Protocol Benefits:

   The immediate focus of CAPWAP is on supporting IEEE 802.11 based
   WLANs.  As such, it is necessary for the protocol to recognize the
   major distinction in WLAN design with respect to IEEE 802.11i
   authenticator and encryption points.  This represents a significant
   variation that has been highlighted in the Architecture Taxonomy.
   The CAPWAP protocol benefits by accommodating such a major
   consideration fro IEEE 802.11i.

   These requirements will be common for all authentication mechanisms
   over the centralized WLAN architecture.  So they are applicable to
   IEEE 802.11i, UMA and other mechanisms.

   Relation to Problem Statement:

   The Problem Statement highlights the availability of different WTP
   designs and the need to ensure interoperability among them.  In this
   regard, operational changes occuring due to the separation of the
   IEEE 802.11i authenticator and encryption points need to be
   accommated within the CAPWAP protocol.

5.1.11  Interoperability Objective

   Classification: Architecture

   Description:

   Two major designs of the centralized WLAN architecture are local-MAC
   and split-MAC.  With the focusing of standardization efforts on these
   two designs, it is crucial to ensure mutual interoperation among
   them.

   This objective for the CAPWAP protocol is to ensure that WTPs of both
   local-MAC and split-MAC architecture designs are capable of
   interoperation within a single WLAN.  Consequently, a single WLAN
   controller will be capable of controlling both types of WTPs using a
   single CAPWAP protocol.  Integral support for these designs comprises
   a number of protocol aspects.

   i.  Capability negotiations between WLAN controller and WTPs




Govindan (Editor), et al.    Expires October 16, 2005          [Page 18]

Internet-Draft              CAPWAP Objectives                 April 2005


   WTP designs differ in the degree of IEEE 802.11 MAC functionalities
   that each type of WTP realizes.  The major distinctions, split-MAC
   and local-MAC differ in the processing of IEEE 802.11 MAC frames.  In
   this regard, the CAPWAP protocol should include functionality that
   allows for negotiationg of significant capabilities between WTPs and
   WLAN controller.

   As a first step, such negotiations could cover the type of WTP -
   split-MAC or local-MAC - as this provides substantial information on
   their respective capabilities.

   ii.  Establishment of alternative interfaces

   The capability differences among different WTPs essentially equates
   to alternative interfaces with a WLAN controller.  So the CAPWAP
   protocol should be capable of adapting its operations to the major
   different interfaces.  In a first case, this would include
   accommodating capability differences between local-MAC and split-MAC
   WTPs.

   The definition of these interfaces in terms of finer granularity of
   functionalities will be based on the outcome of the IEEE AP
   Functionality (APF) Ad-Hoc Committee.  The APF Ad-Hoc Committee will
   provide appropriate insight in to specific functional blocks which
   may be used for finer capabilities negotiations within the CAPWAP
   protocol.

   Protocol Requirement:

   The CAPWAP protocol must include sufficient capabilities negotiations
   to distinguish between major types of WTPs.

   Motivation and Protocol Benefits:

   The benefits of realizing this architecture objective are both
   technical and practical.  First, there are substantial overlaps in
   the control operations of local-MAC and split-MAC architecture
   designs.  The Architecture Taxonomy tabulates major common features
   of the two designs.  As a result, it is technically practical to
   devise a single protocol that        manages both types of devices.

   Next, the ability to operate a CAPWAP protocol for both types of
   architectural designs enhances its practical prospects as it will
   have wider appeal.

   Furthermore, the additional complexity resulting from such
   alternative interfaces is marginal.  Consequently, the benefits of
   this objective will far outweigh any cost of realizing it.



Govindan (Editor), et al.    Expires October 16, 2005          [Page 19]

Internet-Draft              CAPWAP Objectives                 April 2005


   Relation to Problem Statement:

   The objective for supporting both local-MAC and split-MAC WTPs is
   fundamental to addressing the Problem Statement.  It forms the basis
   for those problems to be uniformly addressed across the major WLAN
   architectures.  This is the ultimate aim of standardization efforts.
   The realization of this objective will ensure the development of a
   comprehensive set of mechanisms that address the challenges of large-
   scale WLAN deployments.

5.1.12  Protocol Specifications

   Classification: General

   Description:

   WLAN equipment vendors require sufficient details from protocol
   specifications so that implementing them will allow for compatibility
   with other equipment that run the same protocol.  In this light, it
   is important for the CAPWAP protocol specifications to be reasonably
   complete for realization.

   Protocol Requirement:

   Any WTP or AC vendor or any person can implement the CAPWAP protocol
   from the specification itself and by that it is required that all
   such implementations do interoperate.

   Motivation and Protocol Benefits:

   It is beneficial for WLAN equipment vendors to refer to a single set
   of specifications while implementing the CAPWAP protocol.  This helps
   to ease and quicken the development process.

   Relation to Problem Statement:

   This requirement is based on WG discussions that have determined to
   be important for CAPWAP.

5.1.13  Vendor Independence

   Classification: General

   Description:

   Rapid developments in WLAN technologies results in equipment vendors
   constantly modifying their devices.  In many cases, developments are
   independently made for ACs and WTPs.  The CAPWAP protocol should not



Govindan (Editor), et al.    Expires October 16, 2005          [Page 20]

Internet-Draft              CAPWAP Objectives                 April 2005


   affect the the independence of device modificaitons.

   Protocol Requirement:

   A WTP vendor can make modifications to hardware without any AC vendor
   involvement.

   Motivation and Protocol Benefits:

   Independence in the type of hardware for WLAN equipment ensures that
   new developments do not hamper protocol operation.

   Relation to Problem Statement:

   This requirement is based on WG discussions that have determined to
   be important for CAPWAP.

5.1.14  Vendor Flexibility

   Classification: General

   Description:

   The CAPWAP protocol must not be specified for a particular MAC.  It
   should be compatible with both local-MAC and split-MAC WTPs.

   Protocol Requirement:

   WTP vendors must not be bound to a specific MAC.

   Motivation and Protocol Benefits:

   This requirement is to ensure that WTP vendors have sufficient
   flexibility in selecting the type of MAC that they consider best for
   deployments.

   Relation to Problem Statement:

   This requirement is based on WG discussions that have determined to
   be important for CAPWAP.

5.2  Desirable Objectives

   These objectives have been determined to be desirable for a CAPWAP
   protocol but not mandatory.  Realizing these objectives may help
   improve control of WLANs but need not necessarily be required for all
   networks or scenarios.




Govindan (Editor), et al.    Expires October 16, 2005          [Page 21]

Internet-Draft              CAPWAP Objectives                 April 2005


5.2.1  Multiple Authentication Mechanisms

   Classification: Architecture

   Description:

   Shared WLAN infrastructure raise the issue of multiple authentication
   mechanisms.  This is because each logical group is likely to be
   associated with different service providers or WLAN domains.  As a
   result, the authentication needs withing them will be different.
   While CAPWAP is required to support IEEE 802.11i, it is also
   necessary for it to support other authentication mechanisms.  For
   example, one logical group may use IEEE 802.11i while another may use
   web authentication.  CAPWAP must be able to operate in such shared
   WLANs.

   Protocol Requirement:

   The CAPWAP protocol must support different authentication mechanisms
   in addition to IEEE 802.11i.

   Motivation and Protocol Benefits:

   The benefit of supporting various authentication mechanisms is that
   the protocol then becomes flexible for use in various deployments.
   The protocol will therefore not mandate the use of any particular
   mechanisms which may not be appropriate for a particular deployment.

   Relation to Problem Statement:

   This objective relates to the problem of management complexity.
   Shared WLAN deployments simplifies management of large networks.

5.2.2  Support for Future Wireless Technologies

   Classification: Architecture

   Description:

   The rapid pace of technology developments means that new advances
   need to be catered for in current analyses.  Among these is the
   support for new wireless technologies within the CAPWAP protocol,
   such as IEEE 802.16.  The protocol should therefore not rely on
   specifics of IEEE 802.11 technology.

   In all cases where the CAPWAP protocol messages contain specific
   layer 2 information elements, the definition of the protocol needs to
   provide for extensibility so that these elements can be defined for



Govindan (Editor), et al.    Expires October 16, 2005          [Page 22]

Internet-Draft              CAPWAP Objectives                 April 2005


   specific layer 2 wireless protocols.  This may entail assigning a
   layer 2 wireless protocol type and version field to the message PDU.
   Examples of other wireless protocols that might be supported include
   but are not limited to 802.16e, 802.15.x, etc.

   Protocol Requirement:

   CAPWAP protocol messages must be designed to be extensible for
   specific layer 2 wireless technologies.  It should not be limited to
   the transport of elements relating to IEEE 802.11.

   Motivation and Protocol Benefits:

   There are many benefits to an extensible protocol.  It allows for
   application in different networks and provides greater scope.
   Furthermore, service providers require WLAN solutions that will be
   able to meet current and future market requirements.

   Relation to Problem Statement:

   The Problem Statement describes some of the advances taking place in
   other standards bodies like the IEEE.  It is important for the CAPWAP
   protocol to reflect the advances and provide a framework in which
   they can be supported.

5.2.3  Support for New IEEE Requirements

   Classification: Architecture

   Description:

   The IEEE is currently reviewing IEEE 802.11 functionality.  It is
   expected that the review by the IEEE AP Functionality Ad-Hoc
   Committee may result in new definitions of functional blocks,
   interfaces or information flows.  The CAPWAP protocol must be able to
   incorporate these revisions with minimal change.

   Protocol Requirement:

   The CAPWAP protocol must be openly designed to support new IEEE
   extensions.

   Motivation and Protocol Benefits:

   There are a number of advances being made within the IEEE regarding
   the functionality of IEEE 802.11 technology.  Since this represents
   one of the major wireless technologies in use today, it will be
   beneficial for CAPWAP to incorporate the relevant new extensions.



Govindan (Editor), et al.    Expires October 16, 2005          [Page 23]

Internet-Draft              CAPWAP Objectives                 April 2005


   Relation to Problem Statement:

   The Problem Statement presents an overview of the task of the IEEE
   802.11 working group.  This group is focussed on defining the
   functional architecture of WTPs.  It is necessary for the CAPWAP
   protocol to reflect these definitions.

5.2.4  Interconnection Objective

   Classification: Architecture

   Description:

   Large scale WLAN deployments are likely to use a variety of
   interconnection technologies between different devices of the
   network.  It should therefore be possible for the CAPWAP protocol to
   operate over various interconnection technologies.

   As a result of realizing this objective, the protocol will be capable
   of operation over both IPv4 and IPv6.  It will also be designed such
   that it can operate within tightly administered networks, such as
   enterprise networks, or on open, public access networks.  For
   example, VLAN tunnels can be used across different types of networks
   over which CAPWAP will operate.

   Protocol Requirement:

   The CAPWAP protocol must not be constrained to specific underlying
   transport mechanisms.

   Motivation and Protocol Benefits:

   The main aim of the CAPWAP protocol is to achieve interoperability
   among various WTPs and WLAN controllers.  As such, the motivation for
   this requirement is for the protocol to be operable independent of
   underlying interconnection technologies.

   Relation to Problem Statement:

   The Problem Statement discusses the complexity of configuring large
   WLANs.  The selection of available interconnection technologies for
   large-scale deployments further intensifies this complexity.  This
   requirement avoids part of the complexity by advocating independence
   of the operational aspects of the protocol from from underlying
   transport.






Govindan (Editor), et al.    Expires October 16, 2005          [Page 24]

Internet-Draft              CAPWAP Objectives                 April 2005


5.2.5  Access Control

   Classification: Operations

   Description:

   This objective focuses on the informational needs of WLAN access
   control and specifically the role of the CAPWAP protocol in
   transporting this information between WTPs and their WLAN controller.

   The following are some specific information aspects that need to be
   transported by the CAPWAP protocol;

   i.  IEEE 802.11 association and authentication

   The association of wireless clients is distinct for initial and
   roaming cases.  As a result, access control mechanisms requires
   specific contextual information regarding each case.  Additionally,
   load balancing, QoS, security and congestion information in both
   wireless medium segments and switching segments need to be
   considered.

   ii.  WTP Access Control

   In addition to controlling access for wireless clients, it is also
   necessary to control admission of new WTPs.  Given the threat of
   rogue WTPs, it is important for CAPWAP to relay appropriate
   authentication information between new WTPs and the WLAN controller.

   Protocol Requirement:

   The CAPWAP protocol must be capable of exchanging information
   required for access control of WTPs and wireless terminals.

   Motivation and Protocol Benefits:

   Due to the scale of deployments in which CAPWAP will be employed,
   comprehensive access control is crucial.  The effectiveness of access
   control in turn is affected by the information on which such control
   is based.  As a result, this objective has critical relevance to a
   CAPWAP protocol.

   Relation to Problem Statement:

   This objective addresses the issue of access control in large WLANs.
   Broadly, it relates the problem of managing the complexity scale of
   such networks.  With collective information of both switching and
   wireless medium segments, realizing this objective will help control



Govindan (Editor), et al.    Expires October 16, 2005          [Page 25]

Internet-Draft              CAPWAP Objectives                 April 2005


   and manage complexity.

5.3  Rejected Objectives

   The following objectives have been rejected during the course of
   working group consultations.  These objectives have been rejected in
   the context of CAPWAP and its considerations.  They may however be
   applicable in alternative contexts.

5.3.1  Support for Non-CAPWAP WTPs

   Classification: Architecture

   Description:

   The CAPWAP protocol should provide an engine-mechanism to spring WTP
   auto-configuration and/or software version updates and should support
   integration with existing network management system.  WLAN controller
   as a management agent is optional.

   If entities other than WLAN controllers manage some aspects of WTPs,
   such as software downloads, the CAPWAP protocol may be used for WTPs
   to notify WLAN controllers of any changes made by the other entities.

   Protocol Requirement:

   The CAPWAP protocol should be capable of recognizing legacy WTPs and
   existing network management systems.

   Motivation and Protocol Benefits:

   It is expected that in many cases, the centralized WLAN architecture
   will be deployed incrementally with legacy systems.  In this regard,
   it is necessary for the protocol to be used in scenarios with mixed
   WLAN devices.

   Relation to Problem Statement:

   The Problem Statement highlights management complexity as a major
   issue with large WLANs.  One part of this comlpexity can be related
   to the incremental deployment of centralized WLAN devices for which
   this objective is applicable.

5.3.2  Technical Specifications

   Classification: General

   Description:



Govindan (Editor), et al.    Expires October 16, 2005          [Page 26]

Internet-Draft              CAPWAP Objectives                 April 2005


   The CAPWAP protocol must not require AC and WTP vendors to share
   technical specifications to establish compatibility.  The protocol
   specifications alone must be sufficient for compatibility.

   Protocol Requirement:

   WTP vendors should not have to share technical specifications for
   hardware and software to AC vendors in order for interoperability to
   be achieved.

   Motivation and Protocol Benefits:

   It is beneficial for WLAN equipment vendors to refer to a single set
   of specifications while implementing the CAPWAP protocol.  This helps
   to ease and quicken the development process.

   Relation to Problem Statement:

   This requirement is based on WG discussions that have determined to
   be important for CAPWAP.

   This objective has been prioritized as rejected as it is a duplicate
   of the Protocol Specifications objective (Section 5.1.12).

5.4  Operator Requirements

   The following objectives have been provided by network service
   operators.  They represent the requirements from those ultimately
   deploying the CAPWAP protocol in their WLANs.

5.4.1  AP Fast Handoff

   Classification: Operations

   Description:

   Network service operators consider handoffs crucially because of the
   mobile nature of their customers.  In this regard, the CAPWAP
   protocol should not adversely affect AP fast handoff procedures.  The
   protocol may support optimizations for fast handoff procedures so as
   to allow better support for real-time services during handoffs.

   Protocol Requirement:

   CAPWAP protocol operations must not impede or obstruct the efficacy
   of AP fast handoff procedures.





Govindan (Editor), et al.    Expires October 16, 2005          [Page 27]

Internet-Draft              CAPWAP Objectives                 April 2005


6.  Summary and Conclusion

   The objectives presented in this document address three main aspects
   of the CAPWAP protocol, namely;

   i.  Architecture
   ii.  Operations
   iii.  Security

   These requirements are aimed to focus standardization efforts on a
   simple, interoperable protocol for managing large-scale WLANs.  The
   architecture requirements specify the structural features of the
   protocol such as those relating to WTP types (local-MAC and split-
   MAC) and WTP structures (logical groups).  The operations
   requirements address the functional aspects dealing with WTP
   configuration and management.  Finally, the security requirements
   cover authentication and integrity aspects of protocol exchanges.

   The objectives have additionally been prioritized to reflect their
   immediate significance to the development and evaluation of an
   interoperable CAPWAP protocol.  The priorities are Mandatory and
   Accepted, Desirable and Rejected.  They reflect working group
   consensus on the effectiveness of the requirements in the context of
   protocol design.

   Additionally, this document includes requirements from network
   service operators that have been derived based on their experience in
   operating large- scale WLANs.

   The resulting requirements from this document will be used in
   conjunction with the CAPWAP Problem Statement [I-D.ietf-capwap-
   problem-statement] and CAPWAP Architecture Taxonomy [I-D.ietf-capwap-
   arch] to develop and evalute an interoperable protocol for the
   control and provisioning of WTPs in large-scale WLANs.

















Govindan (Editor), et al.    Expires October 16, 2005          [Page 28]

Internet-Draft              CAPWAP Objectives                 April 2005


7.  Security Considerations

   The CAPWAP framework highlights support for both local-MAC and split-
   MAC WTPs.  In deployments where both types of WTPs are used, it is
   crucial to ensure that each be secured in consideration of their
   capabilities.  The Architecture Taxonomy illustrates how different
   WTPs incorporate varying levels of functionalities.  Development of
   the CAPWAP protocol should ensure that the deployment of both local-
   MAC and split-MAC WTPs within a single WLAN do not present loopholes
   for security compromises.

   In shared WLAN deployments made of a number of logical groups,
   traffic from each group needs to be mutually separated.  So in
   addition to protocol related exchanges, data traffic from wireless
   terminals should also be segregated with respect to the logical
   groups to which they belong.  It should not be possible for data or
   control traffic from one logical group to stray to or influence
   another logical group.

   The use of IEEE 802.11i over the centralized WLAN architecture allows
   for implementations in which the PMK is shared across WTPs.  This
   raises the ambiguity between legitimate sharing and illegitimate
   copies.  Wireless terminals may unknowingly fall prey to or exploit
   this ambiguity.  The resolution of this issue is currently being
   evaluted by the IEEE 802 and IETF liaisons.

   The low-cost of launching attacks on WLANs makes the CAPWAP protocol
   a target.  A first step in securing against any form of attacks is to
   continuously monitor the WLAN for conditions of potential threats
   from rogue WTPs or wireless terminals.  For example, profiles for DoS
   and replay attacks need to be considered for the CAPWAP protocol to
   effectively monitor security conditions.

   The open environment of many WLAN deployments makes physical security
   breaches highly probable.  Compromises resulting from theft and
   physical damage must be considered during protocol development.  For
   instance, it should not be possible for a single compromised WTP to
   affect the WLAN as a whole.

   Considering asymmetric, non-mutual authentication between WTPs and
   WLAN controller, there is a risk of a rogue participant exploiting
   such an arrangement.  It is preferrable to avoid non-mutual
   authentication.  In some cases, the legitimacy of the protocol
   exchange participants may be verified externally, for example by
   means of physical containment within a close environment.  Asymmetric
   authentication may be appropriate here without risk of security
   compromises.




Govindan (Editor), et al.    Expires October 16, 2005          [Page 29]

Internet-Draft              CAPWAP Objectives                 April 2005


8.  Acknowledgements

   The authors would like to thank the Working Group Chairs, Dorothy
   Gellert and Mahalingam Mani, for their support and patience with this
   document.  We would also like to thank participants of the Working
   Group who have helped shape the objectives.  In particular, the
   authors thank James Kempf, Pat Calhoun, Inderpreet Singh, Dan Harkins
   and T. Sridhar for their invaluable inputs.  The authors also
   acknowledge the contributions from Meimei Dang, Satoshi Iino,
   Mikihito Sugiura and Dong Wang.

9.  References

   [I-D.ietf-capwap-arch]
              Yang, L., Zerfos, P., and E. Sadot, "Architecture Taxonomy
              for Control and Provisioning of Wireless Access
              Points(CAPWAP)", draft-ietf-capwap-arch-06 (work in
              progress), November 2004.

   [I-D.ietf-capwap-problem-statement]
              Calhoun, P., "CAPWAP Problem Statement",
              draft-ietf-capwap-problem-statement-02 (work in progress),
              September 2004.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.


Authors' Addresses

   Saravanan Govindan
   Panasonic Singapore Laboratories
   Block 1022, Tai Seng Industrial Estate
   #06-3530, Tai Seng Avenue
   Singapore  534 415
   Singapore

   Phone: +65 6550 5441
   Email: sgovindan@psl.com.sg












Govindan (Editor), et al.    Expires October 16, 2005          [Page 30]

Internet-Draft              CAPWAP Objectives                 April 2005


   Zhonghui Yao
   Huawei Longgang Production Base
   Shenzhen  518 129
   P. R. China

   Phone: +86 755 2878 0808
   Email: yaoth@huawei.com


   Wenhui Zhou
   China Mobile
   53A, Xibianmen Ave, Xuanwu District
   Beijing  100 053
   P. R. China

   Phone: +86 10 6600 6688 ext.3061
   Email: zhouwenhui@chinamobile.com


   L. Lily Yang
   Intel Corp.
   JF3-206, 2111 NE 25th Ave.
   Hilsboro, OR  97124
   USA

   Phone: +1 503 264 8813
   Email: lily.l.yang@intel.com


   Hong Cheng
   Panasonic Singapore Laboratories
   Block 1022, Tai Seng Industrial Estate
   #06-3530, Tai Seng Avenue
   Singapore  534 415
   Singapore

   Phone: +65 6550 5447
   Email: hcheng@psl.com.sg













Govindan (Editor), et al.    Expires October 16, 2005          [Page 31]

Internet-Draft              CAPWAP Objectives                 April 2005


Intellectual Property Statement

   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.


Disclaimer of Validity

   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 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.


Copyright Statement

   Copyright (C) The Internet Society (2005).  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.


Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.




Govindan (Editor), et al.    Expires October 16, 2005          [Page 32]


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