Status ofCAPWAP

Architecture DraftLily Yang

Intel Corp.

March 3, 2004

59th IETF meeting

IETF 59th CAPWAP Architecture 2

Overview

• What happened since last IETF?

• What should this draft cover?

• Where are we today?– Basic thinking– Comments received

• What is the plan going forward?

IETF 59th CAPWAP Architecture 3

draft-ietf-capwap-arch-00• Co-Authors:

– Bob O’Hara (AireSpace)– Lily Yang (Intel)

• Not much change from draft-mani-capwap-arch-00

• New developments since 58th IETF:– WG officially approved– New Charter => new focus on

• Problem Statement• Architecture (taxonomy)

– Architecture draft: WG work item– Timeline: 6 month (by Aug.)– Design Team

• Expectation: Need significant rework on the draft

IETF 59th CAPWAP Architecture 4

What should the architecture draft cover?

• Architecture taxonomy: different ways to implement WLAN functions– Standalone AP architecture– “AP + AC” architecture & its variants in the market

• Pros and Cons for each• Security threats for each• Functional interfaces for each• Interoperability vs flexibility challenge

– Is it feasible to support all variants?– If not, then what?

IETF 59th CAPWAP Architecture 5

WLAN Architecture Defined by 802.11 today

• Services defined by .11:– Station Services:

• Auth./De-auth.• Privacy• MSDU delivery

– Distribution System Services:

• Asso., Disasso., Reasso.• Distribution• Integration (via “portal”)

• Other functions:– Mobility support– AP Load balancing– Dynamic RF mgmt &

control– Better network security– …

Distribution System (DS)

STA3 STA4

AP

STA5 STA6

AP Portal

STA1 STA2

AP

External Network

Implementation of DS is NOT

part of the 802.11 standard.

IETF 59th CAPWAP Architecture 6

802.11 WLAN Architecture I: Autonomous AP

STA 1 STA2

AP

STA 3 STA 4

AP

External Network

• Autonomous (standalone) AP: “fat” and self-contained AP

• No explicit infrastructure support• Each AP provides most of the WLAN functions

within itself.

IETF 59th CAPWAP Architecture 7

802.11 WLAN Architecture II: AP + AC (Access Controller)

STA 1 STA2

AP

STA 3 STA 4

AP

External Network

AP

Access Controller (AC)

• “AP + AC” together implements WLAN functions• Advantages of AC:

– centralized controller(s) => manageability for large networks– network wide visibility => better coordination across the network

• Challenges: – no standard way of splitting => no interoperability

Key Issue: How the WLAN functions are “split” among AP and AC?

IETF 59th CAPWAP Architecture 8

“Split” Spectrum: Architecture & Topology

x

Fat AP(ARCH0)

Antenna AP(ARCH3):AP=AntennaAC = MAC & above

x

Split AP(ARCH1):AP= MACAC= above

x

Split MAC(ARCH2):AP=RT MACAC = NRT & above

x

direct

L3

L2

topology

Split architecture

x

x

x

x

x

x

x

xx

IETF 59th CAPWAP Architecture 9

Comments received so far

• How to categorize the architecture variants:– Not enough info– Need more analysis on pros/cons

• Confusing “architectures” with “topologies”

• Should move away from some assumptions made by LWAPP

Need lots of work!

IETF 59th CAPWAP Architecture 10

The Plan Going Forward

• Functional split of AP and AC

• Network topological considerations

• Security threats • Pros and cons

Architecturevariants

WG ArchitectureTaxonomy

DT Expert review

IEEE

• Data analysis• Categorization• Tradeoff of

Interoperability vs. flexibility

• Recommendations

03/17 v01: ?

AP functional Definition

IETF Protocol(s)

IESG review

?

?

Aug 04

?

IETF 59th CAPWAP Architecture 11

First Call to Action

• Each vendor/participant to submit – WLAN functions supported – How the functions map to AP and AC?– What are the topological assumptions between

AP and AC?– Security analysis on threats– Pros and Cons of the architecture variant

• By March 17 !

IETF 59th CAPWAP Architecture 12

Summary

• We expect to revise the draft significantly.

• One step at a time:– Taxonomy

– Analysis

– Recommendations to IEEE

• Lets do it!