Post on 01-Apr-2015
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.