May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 1

doc.: IEEE 802.11-04/481r3

Submission

Thoughts on AP Functional Descriptions

L. Lily YangSteve Shellhammer

Intel Corp.

lily.l.yang@intel.comStephen.j.shellhammer@intel.com

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 2

doc.: IEEE 802.11-04/481r3

Submission

Overview

• Background & Motivation

• How to achieve interoperability?

• Scoping for “AP Functional Descriptions”

• Requirements and Reality Check

• Open Questions for the new SG/TG

• Summary & Conclusion

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 3

doc.: IEEE 802.11-04/481r3

Submission

Background

• Original “Access Points”:– Logical AP Functions = One Physical Entity (“AP”)

• Subsequently in the industry some vendors have partitioned the AP functionality into different physical entities (Example: AP = AC + WTP)– Logical AP Functions = Combination of Physical

Entities

AP Functions: LogicalAP Functional Descriptions: Logical View

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 4

doc.: IEEE 802.11-04/481r3

Submission

Motivation: Interoperability

• Interest from IETF: defining a protocol between these physical entities to allow interoperability in the WLAN market

Physical Entity X

(Access Controller):From vendor A

Physical Entity Y

(Wireless TerminationPoint):

From vendor B

X-YProtocol

interoperable

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 5

doc.: IEEE 802.11-04/481r3

Submission

How to achieve interoperability?

Physical Entity X

(AC)

Physical Entity Y(WTP)

X-YProtocol

IETF interest

First Step: Need help from IEEE

Logical Functions for“AC+WTP”

= “AP Functionality”

It takes efforts from both IEEE and IETF

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 6

doc.: IEEE 802.11-04/481r3

Submission

Additional Benefit of “AP Functional Descriptions”

• A trend in 802.11 WG: from “link view” to “wireless network view”– 11e, 11n => 11r, 11s

• Natural evolution for WLAN architectures– One box AP with BSS-centric view: “Autonomous Architecture”– The need for better coordination to provide inter-BSS services

• “Centralized Architecture”: centralized controller for the whole network

• “Distributed Architecture”: distributed coordination by peer nodes (example: mesh)

• Original AP definitions: interaction with DS is vague– No interoperability within ESS

• Need to provide better definitions of ESS and interoperability within ESS

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 7

doc.: IEEE 802.11-04/481r3

Submission

Why by IEEE 802.11?

• The 802.11 WG defines the MAC and PHY layers, which are the basis for construction of an AP

• The 802.11 WG embodies the subject matter experts that best understand the workings of an AP and

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 8

doc.: IEEE 802.11-04/481r3

Submission

• What’s in the scope?– Clear logical decomposition of the AP functionality

into some logical units (modules, services, functions, or whatever makes sense)

– Clear description of the interaction, relationship or interfaces between these logical units

• What’s out of the scope?– Physical mapping of these logical units onto physical

entities (this implies a specific architecture: belongs to other groups)

Scoping for “AP Functional Descriptions”

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 9

doc.: IEEE 802.11-04/481r3

Submission

• Better description to– Allow WLAN architecture flexibility and

innovation– Facilitate interoperability (possibly with

additional work done elsewhere)

• Provide common framework for existing and future WLAN architecture development

Basic Requirements for “AP Functional Descriptions”

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 10

doc.: IEEE 802.11-04/481r3

Submission

Reality Check• How future proof can it really be? (Common challenge for

any technology development)

• Architecture flexibility

Support infinite number of arbitrary architectures– Figure out the relevant architectures in today’s market

– Study the evolutional path from past and present

– Keep eyes on the emerging architectures on the horizon

• Interesting architecture examples for study (from IETF CAPWAP WLAN Architecture Taxonomy Document):– Autonomous Architecture

– Centralized Architecture (with centralized Access Controller)

– Distributed Architecture (peer-to-peer coordination)

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 11

doc.: IEEE 802.11-04/481r3

Submission

Need to form a new SG• To work on better “AP Functional Definitions”• Some open questions for SG to investigate

– What do we have today in the Standards (as starting points)?

– What is missing, lacking, or confusing?– How to approach the functional decomposition

(methodology, granularity)?– How to describe the interface or interaction?– How to better separate data plane and control plane?– What kind of documents will be produced in the end?– What impact does it have on other 802.11 groups?

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 12

doc.: IEEE 802.11-04/481r3

Submission

Reference Model in 802.11(Clause 5 & 10)

PMD

PLCP

MACStation

Management Entity(SME)

MLME

PLME

MACMIB

PHYMIB

MAC_SAP

PHY_SAP

PMD_SAP

MLME_PLME_SAP

MLME_SAP

PLME_SAP

Does this represent the whole picture accurately?

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 13

doc.: IEEE 802.11-04/481r3

Submission

AP Architecture in IAPP (11F)

Can we generalizethis beyond IAPP?

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 14

doc.: IEEE 802.11-04/481r3

Submission

Data Plane Architecture from 11i

Is this a betterapproach?

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 15

doc.: IEEE 802.11-04/481r3

Submission

Suggested Next Step for IEEE 802.11 WG

• Form a new IEEE 802.11 SG/TG to provide better AP functional descriptions – Clear logical decomposition of AP functionality– Clear description of the interfaces – Harmonize across different WLAN

architectures• Centralized Architectures (with IETF CAPWAP)

• Distributed Architecture (with IEEE 802.11s)

May 2004

Lily Yang, Steve Shellhammer, Intel

Slide 16

doc.: IEEE 802.11-04/481r3

Submission

Summary

• Share our thoughts on AP Functional Descriptions– Why? Interoperability.– How? First step is to have common understanding of

what constitute “AP functions”.– What? Functional decomposition and interfaces.

• Very important first step toward interoperability– Other groups can use this and develop additional

protocols to achieve interoperability for a particular architecture

• Conclusion: a new study group is needed in 802.11 WG to accomplish this.