status of capwap architecture draft lily yang intel corp. march 3, 2004 59 th ietf meeting

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!