Saravanan Govindan

1
CAPWAP Classifications Requirements

• Saravanan Govindan
• Panasonic
• 4 August, 2004
• ltdraft-cheng-capwap-classifications-01.txtgt

2
CAPWAP Taxonomy

• Current marketplace has a number of WLAN
  architectures
• Each addressing a different deployment case, e.g.
  switched, mesh
• Each emphasizing a distinct aspect, e.g.
  management, scale
• Architecture Taxonomy documents the various
  designs
• Taxonomy defines a number of design variations
• Autonomous, Centralized, Mesh, Local MAC, Remote
  MAC etc.
• No single design addresses all requirements of
  all deployments
• Yet, we want interoperation for combined benefits
  and improved flexibility
• Way forward is to integrate the major designs to
  enable choice

3
Classification of Function Blocks

• Major challenge with interoperability is
  diversity of split architectures
• Taxonomy details types of WTPs, each with
  different degrees of functionality
• Need for distinct WTPs to operate within a single
  WLAN environment
• One way is to enable adaptive interfaces between
  controllers (AC) and WTPs (draft-cheng-capwap-clas
  sifications-01)
• Determine functional capabilities of WTPs
• Then use the information together with
  configuration policies to establish unique
  interfaces between AC and WTPs
• So if basic function blocks and their interfaces
  are standardized, larger issue of
  interoperability is simplified
• Comes down to applying the policies of Section
  2.1 on the standardized blocks
• Then establishing appropriate interfaces with
  various WTPs
• CAPWAPs role could then be to provide a base on
  which such policies can operate
• First step is to establish the basic function
  blocks for WLAN operations
• IEEE AP Functionality Study Group is looking at
  functional definitions
• These efforts can be used for classifications

4
Classification of Function Blocks
Operational Sequence
802.11 Services
Functional Blocks
(a1)
Verification of Association Request
Association Service
(a1)
(a2)
(a2)
Updation of Association Entry
(m1)
MSDU Delivery
Traffic Aggregation Distinction
(m1)
Functional Block Relations
5
Framework

• CAPWAP framework to focus on enabling diverse
  WTPs to operate within single AC domain
• Interoperability can be achieved by allowing
  different AC-WTP interfaces to co-exist
• It is expected that there will be a limited
  number of blocks
• Changes required for realizing the policies are
  primarily at the AC
• In addition to incorporating the function blocks,
  various usage scenarios for CAPWAP need to be
  considered
• The draft makes a start in this direction
• Scenarios will then give rise to requirements for
  CAPWAP

6
Requirements

• Before detailed development work, WG can consider
  specific requirements to be addressed
• Architecture Taxonomy is a good place to start
• Come up with CAPWAP scenarios and then derive
  requirements from them
• Classifications draft makes a start in this
  direction
• An initial exercise has resulted in some
  requirements for CAPWAP framework, e.g.
• Adaptive interfaces
• Shared infrastructure
• Multiple authentication mechanisms
• These items may be considered for future work
• Additions/alterations to the requirements to be
  based on WG discussions

7
Possible Path Forward

• An explicit requirements gathering phase before
  actual protocol development
• This will help in evaluating candidate protocols
• It is important to establish what exactly CAPWAP
  needs and then address them using various
  (combination of) solutions
• Architecture Taxonomy can be used to come up with
  scenarios
• Additional scenarios will be needed for more
  complete coverage
• Broader input from WG in this regard will be
  necessary
• Classifications draft makes a start in this
  direction