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Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke Maximilian Riegel Siemens AG, ICM Networks 2002-10-02

Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

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Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke. Maximilian Riegel Siemens AG, ICM Networks 2002-10-02. Outline. WLAN Standardization overview The IEEE802.11 WLAN Standard Architecture Physical layer Spectrum issues MAC layer functions Configurations - PowerPoint PPT Presentation

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Page 1: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

Maximilian RiegelSiemens AG, ICM Networks2002-10-02

Page 2: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 2 © Siemens, 2002

Outline

WLAN Standardization overview The IEEE802.11 WLAN Standard

– Architecture– Physical layer– Spectrum issues– MAC layer functions– Configurations– Handover– Power Management– Privacy and access control

WLAN Security WLAN – UMTS Interworking

– Tight coupling– Market and application considerations– Loose coupling– Standardization activities

Page 3: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 3 © Siemens, 2002

Wireless LAN Standardization

MAC

PHY

Current standardization topics

HiperLAN/2

DFS & TPC

5 GHz54 Mbit/s

ETSI BRAN

UMTS Integration 802.11f: Inter Access Point Protocol

IEEE 802.11

IEEE 802.11

2,4 GHz2 Mbit/s

802.11b2,4 GHz11Mbit/s

802.11g2,4 GHz54Mbit/s

802.11a5 GHz

54Mbit/s

802.11e: QoS Enhancements

802.11i: Security Enhancements

802.11hDFS & TPC

WIGWireless

Interworking Group

Page 4: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 4 © Siemens, 2002

The ubiquitous WLAN

Today’s road worriers require access to the Internet everywhere.

WLAN is more than just cable replacement, it provides hassle-free broadband Internet access everywhere.

Coverage in ‘hot-spots’ sufficient. IEEE802.11b meets the expectations for easiness, cost

and bandwidth.

PublicWLAN

Airport

Railway Station

Campus

Plant

Semi-publicWLAN

OfficeHospital

Congress hall,Hotel

Corporate WLAN

Office

HomeWLAN

Remote Access

Page 5: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 5 © Siemens, 2002

Wireless IEEE802.11 Standard

Approved June 1997– 802.11b approved Sept. 1999

Operation in the 2.4GHz ISM band– USA: FCC part 15.247-15.249– Europe: ETS 300-328 – Japan: RCR-STD-33A

Supports three PHY layer types: DSSS, FHSS, Infrared

MAC layer common to all 3 PHY layers Supports peer-to-peer and

infrastructure configurations IEEE802.11b high data rate extension with 11 Mbps

using existing MAC layer IEEE802.11a for operation in the 5 GHz band with up to

54 Mbit/s using the same MAC layer

Page 6: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 6 © Siemens, 2002

httptcpip

pppBluetooth

Netscape

ip802.2802.11

802.2802.11 802.3

802.2802.3

802.2802.3

httptcpip

pppBluetooth

apache

ip802.2802.3

ip

IEEE802.11

local distribution network internet

Client Access Point Access Router Server

Wireless LAN IEEE802.11Basic Architecture

Page 7: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 7 © Siemens, 2002

IEEE802.11 Protocol Architecture

Station Management– interacts with both MAC Management

and PHY Management MAC Layer Management Entity

– power management

– handover

– MAC MIB MAC Entity

– basic access mechanism

– fragmentation

– encryption PHY Layer Management

– channel tuning

– PHY MIB Physical Layer Convergence Protocol (PLCP)

– PHY-specific, supports common PHY SAP

– provides Clear Channel Assessment signal (carrier sense) Physical Medium Dependent Sublayer (PMD)

– modulation and encoding

MAC Sublayer

PLCP Sublayer

PMD Sublayer

MAC LayerManagement

PHY LayerManagement

StationManagement

LLC = 802.2

MAC

PHY

Page 8: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 8 © Siemens, 2002

IEEE 802.112.4 GHz & 5 GHz Physical Layers

TimeF

requency

2.4 GHz Frequency Hopping Spread Spectrum– 2/4 FSK with 1/2 Mbps– 79 non overlapping frequencies

of 1 MHz width (US)

FrequencyP

ower

Frequency

Pow

er

spreading

2.4 GHz Direct Sequence Spread Spectrum– DBPSK/DQPSK with 1/2 Mbps – Spreading with 11 Bit barker Code – 11/13 channels in the 2.4 GHz band

2.4 GHz High Rate DSSS Ext. (802.11b)– CCK/DQPSK with 5.5/11 Mbps

Frequency

Pow

er

5 GHz OFDM PHY (802.11a)– Basic parameters identical to

HiperLAN2 PHY– European regulatory issues unsolved

Baseband IR, 1 and 2Mbps, 16-PPM and 4-PPM

Page 9: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 9 © Siemens, 2002

IEEE802.11g: Further Speed Extension for the 2.4GHz Band

Mandatory: CCK w/ short preample (802.11b) and OFDM (802.11a applied to 2.4

GHz range). Optional: PBCC proposal for 22 Mbit/s from Texas Instruments Optional: CCK-OFDM proposal for up to 54 Mbit/s from Intersil

Upcoming

Upcoming

Upcoming

Upcoming

Range vs. throughput rate comparison of CCK (802.11b), OFDM(“802.11a”), PBCC, CCK-OFDM(Batra, Shoemake; Texas Instruments; Doc: 11-01-286r2)

Page 10: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 10 © Siemens, 2002

Freq./GHz

5.200 5.300 5.400 5.500 5.600 5.700 5.800 5.9005.100

Europe

USA

Japan5.150 5.250

5.150 5.350 5.725 5.825

Indoor 200 mW / Outdoor 1 W EIRP Outdoor 4 W EIRP

Max peak Tx power

5.3505.150 5.470 5.725

Outdoor 1W EIRP Indoor 200 mW EIRP

Max mean Tx power

DFS & TPC DFS & TPC

DFS: Dynamic Frequency Selection

TPC: Transmit Power Control

Spectrum Designation in the 5 GHz range

Many European countries are currently opening 5 GHz range for radio LANs.

Page 11: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 11 © Siemens, 2002

IEEE802.11h: Spectrum and Transmit Power Management

TPC (Transmission power control) – supports interference minimisation, power consumption reduction,

range control and link robustness.– TPC procedures include:

• AP‘s define and communicate regulatory and local transmit power constraints

• Stations select transmit powers for each frame according to local and regulatory constraints

AP 1AP 2

AP 3

STA

DFS (Dynamic Frequency Selection)– AP‘s make the decision– STA‘s provide detailed reports

about spectrum usage at theirlocations.

Upcoming

Upcoming

Upcoming

Upcoming

Page 12: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 12 © Siemens, 2002

… when will 5 GHz WLANs come?

IEEE802.11b (2.4 GHz) is now taking over the market. There are developments to enhance IEEE802.11b for

– more bandwidth (up to 54 Mbit/s)– QoS (despite many applications do not need QoS at all)– network issues (access control and handover).

5 GHz systems will be used when the 2.4 GHz ISM band will become too overcrowded to provide sufficient service.– TCP/IP based applications are usually very resilient

against ‘error proune’ networks.

Issues of 5 GHz systems:– Cost: 5 GHz is more expensive than 2.4 GHz– Power: 7dB more transmission power for same distance– Compatibility to IEEE802.11b/g necessary

Page 13: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 13 © Siemens, 2002

DIFSContention Window

Slot time

Defer Access

Backoff-Window Next Frame

Select Slot and Decrement Backoff as long as medium is idle.

SIFS

PIFSDIFS

Free access when mediumis free longer than DIFS

Busy Medium

CSMA/CA Explained

Reduce collision probability where mostly needed.– Stations are waiting for medium to become free.– Select Random Backoff after a Defer, resolving contention

to avoid collisions. Efficient Backoff algorithm stable at high loads.

– Exponential Backoff window increases for retransmissions.

– Backoff timer elapses only when medium is idle. Implement different fixed priority levels

IFS: Inter Frame Space

Page 14: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 14 © Siemens, 2002

IEEE802.11e: MAC Enhancementsfor Quality of Service (EDCF)

– differentiated DCF access to the wireless medium for prioritized traffic categories (4 different traffic categories)

– output queue competes for TxOPs using EDCF wherein• the minimum specified idle duration time is a distinct value

• the contention window is a variable window

• lower priority queues defer to higher priority queues

EDCF (Enhanced Distributed Coordination Function)

Upcoming

Upcoming

Upcoming

Upcoming

Mapping toAccess Category

Transmit Queues

Per-queuechannel accessfunctions withinternal collisionresolution

Page 15: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 15 © Siemens, 2002

Beacon

Contention Free Period Contention Period

CFP repetition interval

D1+Poll

U1+ACK

D2+Poll

Stations

AccessPoint

U2+ACK

CF end

IEEE802.11Point Coordination Function (PCF)

Optional PCF mode provides alternating contention free and contention operation under the control of the access point

The access point polls stations for data during contention free period

Network Allocation Vector (NAV) defers the contention traffic until reset by the last PCF transfer

PCF and DCF networks will defer to each other PCF improves the quality of service for time bounded data

Page 16: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 16 © Siemens, 2002

IEEE802.11e: MAC Enhancements for Quality of Service (HCF)

– only usable in infrastructure QoS network configurations– allow a uniform set of frame exchange sequences to be

used during both the contention period (CP) and contention free period (CFP)

– uses a QoS-aware point coordinator, called a hybrid coordinator

• by default collocated with the enhanced access point (EAP)

• uses the point coordinator's higher priority to allocate transmission opportunities (TxOPs) to stations

– provides limited-duration contention free bursts (CFBs) to transfer QoS data.

– meets predefined service rate, delay and/or jitter requirements of particular traffic flows.

– ...– „Quite complex method still under definition“

HCF (Hybrid coordination function)

Upcoming

Upcoming

Upcoming

Upcoming

Page 17: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 17 © Siemens, 2002

Peer-to-Peer Network

IEEE802.11 Ad Hoc Mode

Independent networking– Use Distributed Coordination Function (DCF)– Forms a Basic Service Set (BSS)– Direct communication between stations– Coverage area limited by the range of individual stations

Page 18: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 18 © Siemens, 2002

BSS-A

Distribution System (DS)

BSS-B

Server

IEEE802.11 Infrastructure Mode

Access Points (AP) and stations (STA) BSS (Basic Service Set): a set of stations controlled by

a single coordination function Distribution system interconnects multiple cells via

access points to form a single network Extends wireless coverage area and enables roaming

Page 19: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 19 © Siemens, 2002

IEEE802.11 Handover

Station decides that link to its current AP is poor

Station uses scanning function to find another AP– or uses information from

previous scans

Station sends Reassociation Request to new AP

If Reassociation Response is successful – then station has roamed to the new AP– else station scans for another AP

If AP accepts Reassociation Request– AP indicates Reassociation to the Distribution System– Distribution System information is updated– normally old AP is notified through Distribution System

Access Point A

Access Point B

Station 4

Access Point C

Station 1

Station 2

Station 3

Station 5Station 6

Station 7

Page 20: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 20 © Siemens, 2002

IEEE802.11f: Inter-Access Point Protocol (IAPP)

IAPP defines procedures for– automatic configuration handling of access points– context transfer between APs when stations move

Distribution SystemServer

IAPP-MOVE

IAPP-ADD

Upcoming

Upcoming

Upcoming

Upcoming

RADIUS Server

Page 21: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 21 © Siemens, 2002

TIM

TIM-Interval

Time-axis

Busy Medium

Tx operation

AP activity

TIM TIM TIM DTIMDTIM

DTIM interval

PS Station

Broadcast

PS-Poll

Broadcast

IEEE802.11 Power Management

Stations wake up prior to an expected DTIM (Delivery Traffic Indication Message).

If TIM indicates frame buffered – station sends PS-Poll and stays awake to receive data– else station sleeps again

Broadcast frames are also buffered in AP.– all broadcasts/multicasts are buffered– broadcasts/multicasts are only sent after DTIM.– DTIM interval is a multiple of TIM interval

Page 22: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 22 © Siemens, 2002

IEEE802.11 Privacy and Access Control

Goal of 802.11 is to provide “Wired Equivalent Privacy” (WEP)– Usable worldwide

802.11 provides for an authentication mechanism– To aid in access control.– Has provisions for “OPEN”, “Shared Key” or proprietary

authentication extensions.

Shared key authentication is based on WEP privacy mechanism– Limited for station-to-station traffic, so not “end to end”.– Uses RC4 algorithm based on:

• a 40 bit secret key

• and a 24 bit IV that is send with the data.

• includes an ICV to allow integrity check.

Page 23: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 23 © Siemens, 2002

Shortcomings of plain WEP security

WEP unsecure at any key length– IV space too small, lack of IV replay protection– known plaintext attacks

No user authentication– Only NICs are authenticated

No mutual authentication– Only station is authenticated against access point

Missing key management protocol– No standardized way to change keys on the fly– Difficult to manage per-user keys for larger groups

WEP is no mean to provide security for WLAN access,– … but might be sufficient for casual cases.

Page 24: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 24 © Siemens, 2002

Associate

EAP Identity Request

EAP Identity Response

EAP Request

EAP Response

EAP Success

Access Request

Access Challenge

Access Request

Access Accept

AuthenticationServer

IEEE802.11i: Enhanced security

Enhanced encryption– WEP2 w/ increase IV space to 128bit, key length 128bit– optional: Advanced Encryption Standard (AES)

Authentication and key management by adoption of IEEE802.1X Standard for Port Based Network Access Control

Upcoming

Upcoming

Upcoming

Upcoming

Page 25: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 25 © Siemens, 2002

A last word about WLAN security:

Even IEEE802.11i may not be sufficient for public hot-spots:

Only VPN technologies (IPSEC, TLS, SSL) will fulfil end-to-end security requirements in public environments.

VPN technologies might even be used in corporate WLAN networks.

http

ipppp

Netscape

ip802.2 802.2

802.3802.2802.3

802.2802.3

http

ipppp

Bluetooth

apache

ip802.2802.3

ip

WEP802.11 802.11

tcp tcp

802.11802.11

IPSEC, TLS, SSLtcp tcp

Page 26: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 26 © Siemens, 2002

PSTN

PLMN access

PLMN coreVLR

HSSAUC

SGSN

SCPLNPIN

GGSN

TDM / ATM / IPMSCSMSCS

BTSBTS BSC

BTSBTS

Node BNode B

Node BNode B

RNC

internet

wlan local access network

WLAN – UMTS Interworking: Ancient approach: ‘tight coupling’

WLAN as just another radio access technology of UMTS All UMTS services become available over WLAN.

but: PLMN is burdened with high bandwidth WLAN traffic. Wi-Fi does not provide all the functionality needed (QoS, security).

Page 27: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 27 © Siemens, 2002

UMTS and Wireless LAN are different.

GSM/GPRS/UMTS

anytime / everywhere voice, realtime messaging QoS precious bandwidth carrier grade operator driven huge customer base high revenues

WLAN IEEE802.11

sometimes / somewhere standard web applications best effort cheap bandwidth corporate technology market driven casual users low revenues

Page 28: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 28 © Siemens, 2002

WLAN is much cheaper than 2G/3G

* based on current IP volume prices of 40€ /GByte.Time based pricing results in similar costs,e.g. MobileStar Pulsar pricing plan: $0,10/min

0

2

4

6

8

10

GPRS GSM-HSCSD WLAN*

0,01

0,1

1

10

GPRS GSM-HSCSD

WLAN

Transfer-Cost [€]Duration [min]

logarithmic scale€

-99,6%

Transfer cost/duration of an 1 Mbytes .ppt/.doc/.xls File...

4 min 4 min 5 sec

Page 29: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 29 © Siemens, 2002

Becoming a WLAN operator is easy.

Legal aspects:– Usage of license free spectrum (2,4 GHz ISM band)– No telecommunication license necessary, as long as

• not providing telephony services,

• not providing network access across borders of private premises.

Cost issues:– The lower bound:

Investment: WLAN Access Point /w DSL Router (~ 350 €)Monthly operation cost: ~ 60 € for DSL Flat Rate

– Most commercial installations are much more expensive due to charging and billing.

It is very easy and extremely cheap to become a WLAN operator, but most people did not yet know about it.

...but wait until they have installed WLAN in their living rooms!

Page 30: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 30 © Siemens, 2002

PSTN

PLMN access

PLMN coreVLR

HSSAUC

SGSN

SCPLNPIN

TDM / ATM / IPMSCSMSCS

BTSBTS BSC

BTSBTS

Node BNode B

Node BNode B

RNC

internet

wlan local access network

WLAN – UMTS Interworking: Now widely accepted: ‘loose coupling’

Only Authentication, Authorization and Accounting of WLAN access is performed by the mobile network operator.

Revenues without competing against aggressive WLAN operators. Perfect model for leveraging the huge customer base and

establishing a widely accepted platform for mobile commerce.

AuthenticationAccounting

Siemens contributed ‚loose coupling‘ to standardization.

Page 31: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 31 © Siemens, 2002

mobile network

HLR

E.g.: Web based authentication and mobile network security

internet

Password:

Username:

auth

html

RADIUSclient

N

auth

DHCPServer

AAAServer

AccessGateway

MobileClient

**********

SMS containing Password

0172-3456789

Page 32: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 32 © Siemens, 2002

Standards for WLAN/UMTS interworking

3GPP– R5: SA1

Requirements of 3GPP system – WLAN interworking. – R6: SA2

Continuation with architectural considerations ETSI BRAN

Subgroup on “Interworking between HiperLAN/2 and 3rd generation cellular and other public systems”. – Detailed architectural description mainly based on the

Siemens ‘loose coupling’ principle established– IEEE802.11 and MMAC are now joining this effort.

=> Wireless Interworking Group (WIG). WECA (Wireless Ethernet Compatibility Alliance)

‘Wireless ISP Roaming Initiative’– Detailed functional specification for roaming (loose

coupling) between IEEE802.11 WLAN networks available.– Mainly aimed for roaming between ISPs but also well

applicable for MNOs.

Page 33: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 33 © Siemens, 2002

The end

Thank you for your attention.

Questions and comments?

Maximilian Riegel

[email protected]

http://www.max.franken.de/

Page 34: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 34 © Siemens, 2002

Services andapplications

IP based core network

IMT-2000(UMTS)

WLANtype

cellular2nd. gen.

WirelinexDSL

DigitalBroadcast

return channel:e.g. cellular

download channel

New radiointerface

WLAN – UMTS interworking is laying the path for the future of networking…

From the ITU-R vision of Wireless Communications beyond 3G:

Seamless network of complementary access systems

Page 35: Aktuelle Entwicklungen in der Standardisierung für drahtlose lokale Netzwerke

M. Riegel, WLAN Standardization, 021002-wlan-informatik2002.ppt Page 35 © Siemens, 2002

Internet/Web Applications

Generic Internet Network Architecture

Internet

linkphy

iptcphttpwww

linkphy

iplinkphy

iplinkphy

iplinkphy

ip802.2802.11

linkphy

ip802.2802.11

iptcphttpwww

Peer(Client)

Peer(Web-Server)

802.2802.3

ip802.2802.3

Policy Server AAA Server

WLAN Access