WiFi Hotspot Service Control - docshare01.docshare.tipsdocshare01.docshare.tips/files/23572/235722830.pdfTerminate PPP session into VR/VRF or ... • Adopted in the corporate market

Copyright © 2003 Juniper Networks, Inc. Proprietary and Confidential www.juniper.net 1

WiFi Hotspot Service Control

Design & Case Study Overview

Simon Newstead

APAC Product Manager

[email protected]

mailto:[email protected]

2 Copyright © 2003 Juniper Networks, Inc. CONFIDENTIAL www.juniper.net

Agenda

Overview of different access models

Identifying the user location

Secure access options

Case studies (as we go)


MPLS

Backbone

WiFi control - access models PPPoE

WiFi User with

PPPoE client

(WinXP or 3rd party)

Access

Controller

BRAS

Layer 2

Backhaul

Transport

(Bridged1483,

Metro E)

RADIUS

LNS*

PPPoE

connection

AAAA

Terminate PPP session into VR/VRF or

tunnel on via L2TP

Fine grained QoS / bandwidth control

Dynamic Policy Enforcement (COPS)

Lawful Intercept etc…

Policy

Server


PPPoE access model - discussion

Pros:

• Full per user control with inbuilt PPP mechanisms (authentication, keepalives etc.)

• Individual policy control per user simplified

• Wholesale is simplified and possible at layer 2 and layer 3

• Leverages the broadband BRAS model used in DSL – virtually no changes

Cons:

• Requires external client software (maybe even with XP) – no “auto launch” by default

• Only works in a bridged access environment; often not possible

• Layer 3 access network requires use of native LAC client (BRAS acts as LNS or tunnel switch) – client support issues


PPPoE access model Case Study – Japanese Provider

WiFi Users with

PPPoE client

[email protected]

Access

Controller

BRAS

ATM

Bridged

1483

RADIUS

Mapping of user to VR based on

RADIUS, domain mapping

Bridging

DSL

modem

Hotspot

AP

Bridging

DSL

modem

Backbone

WiFi VR

ISP VR

DSL Users with

PPPoE client

[email protected]

WiFi

operator

network


MPLS

Backbone

WiFi control - access models DHCP model – Web Login

WiFi User with

inbuilt DHCP client.

Access

Controller

BRAS

Layer 2 or

Layer 3

Backhaul

(any)

External

DHCP

Server* DHCP

DHCP Server or Relay*

Initial policy route to Web logon server

Fine grained QoS / bandwidth control

Dynamic Policies (COPS)

Accounting

Lawful Intercept etc…

Policy Server /

Web Login Server


DHCP Web Login model - discussion

Pros

• No external client software – inbuilt DHCP – lower barriers

• Any access network – eg L3 wholesale DSL, routed Ethernet etc

• Web Login provides extra options to operator (branding, advertising, location based content…)

Cons:

• Wholesale options restricted eg- address allocation – NAT introduces complications (ALG support etc), no tunnelling with L2TP

• Greater security / DoS implications – attack DHCP server, Web server

• No autologon by default (manual web login process)

Need to introduce mechanisms to enable per user control in DHCP environment (mimic PPP)


DHCP / Web login Case Study –

Telstra Mobile

Mobile centric service, launched in August 2003

• Available in hotspot locations throughout Australia

• Target of 600 hotspot locations in 2004 (Qantas, McDonalds, Hilton etc)

• International roaming through the Wireless Broadband Alliance

• Time based billing; hourly rate

• Login via a password delivered by SMS to a Telstra mobile (credit card payment option for non-Telstra post-paid mobile customers)

Lowered barriers to uptake

• No special WLAN subscription needed – casual pay-per-user

• Captive portal logon using DHCP – no client software required


• User opens up web browser and tries to go to Google

• Session directed to captive portal on policy server

• Choice to enter mobile phone number or username and password

• Mobile phone number entered

How it works - Step One


• One-time password sent via SMS to user’s mobile phone

• Received password entered into portal page

Step Two


• Upon successful authentication, captive portal is released and original web destination is loaded.

• Mini-logout window to facilitate signoff.

• Usage billed to user’s mobile phone bill once finished

Step Three


• Allow greater flexibility of services eg-

• Free access to Internet for 15 mins without login… or

• Internet access only, mail port blocked…or

• Internet access but only at 64kbps…or

• Walled garden content only

• Bandwidth can be dynamically increased and restrictions moved on user authentication and login

• Also helps protect against abusive or Worm users (eg- dynamically limit users down on sliding window basis; consumed more than x MB in past 15 mins)

Dynamic Policies


Per user control in a DHCP environment

Objective - make an IP host on single aggregated interface appear like its own IP interface

• Treat hosts as separate logical (demultixed) IP interfaces aka “Subscriber Interfaces”

• Individual policy control on subscriber interface (linked to policy server) – eg filters, bandwidth control

• Ties into DHCP dynamically

VLAN

101

L3 Switch

User A: 192.168.1.1

User B: 192.168.1.2

Subscriber Interface A IP Demux 192.168.1.1

Rate Limit Internet to 512k

Subscriber Interface B IP Demux 192.168.1.2

Rate Limit Internet to 2M Prioritise VoIP to strict

priority queue Add firewall policies

Access

Controller

BRAS


Access Controller

BRAS

1. IP assignments through DHCP & subscriber interface come up – Dynamic SI

DHCP relay point

Upstream Router Routing

Layer AP

GE GE GE FE

2. HTTP redirected and show the portal web page

3. Input subscriber ID and password

Radius

Weblogin - Policy Server

Switch Layer

4. Radius authentication

4. Download policies

Internet & service access

inbuilt DHCP server

1. (Access the portal & click on logout button) or (DHCP lease expired)

WEB login sequence

WEB logout sequence

2. Radius accounting

2. (Reset policies) or (Delete subscriber interface) – Dynamic SI

Generic Web Login process


Location information – why??

Generates portal pages based on hotspot location

Enables targeted advertising. eg- promotions for the owner of the hotspot location, revenue sharing (charging models) etc…

Hotspot –

Cafe

Hotspot –

Train Station Portal - Free access

to timetables, fares..

Portal - Free

sports news..

Access Controller

BRAS

Weblogin - Policy Server


Location information – how?

PPPoE model

• Easy – layer 2 circuit per hotspot to AC/BRAS

• RADIUS will contain NAS Port ID etc…map back centrally

DHCP model (rely on relay to provide)

• Gateway address (GiAddr field)

• Option 82 information, suboptions (ala RADIUS VSAs)

• Or even layer 3 GRE tunnel back if access network can’t provide info required (also simplifies routing)


Side topic – routing back to WiFi user in DHCP environment

Use location based info to allocate users from address pools; one pool per

• Aggregate routes

• Static, redistributed to IGP; simplified

Central pools ok but..

• Require DHCP relay to store state - snoop address coming back from the server in DHCP offer / ACK

• Also requires redistribution into IGP; scaling issues with that…


Secure access

Why?

• Various access vulnerabilities in simple models

• Session hijacking / spoofing, man in the middle

Two main approaches:

• IPSEC tunneling model

• 802.1x/EAP


MPLS

Backbone

WiFi secured access IPSEC option

WiFi User with

inbuilt IPSEC client

Eg- Win2k, WinXP

Access

Controller

BRAS

Any Backhaul

Transport

RADIUS

LNS*

L2TP/IPSEC

connection

(RFC3193)

Terminate IPSEC

BRAS control of PPP session

Policy

Server


IPSEC WiFi access

Pros

• No external client software – inbuilt into Windows

• PPP model gives full per user control (eg- terminate IPSEC and tunnel on L2TP)

• Integrates well into a VPN environment; user sessions terminated to MPLS VPNs at AC/BRAS (PE)

• Can use digital certificates to ensure identity (server and maybe clients also)

Cons:

• Client issues – overhead, PDA support (eg- WinCE today only supports MSCHAPv2?)


IPSEC WiFi access Japan Case Study

Integration of VPN access for mobile corporate users regardless of

access type

Outsource remote access management from corporates, and aggregate

users in a layer 3 VPN – common point of subscriber management

Network diagram:

Access Controller

- BRAS (PE)

WiFi User with native

Windows Client

IPSEC / L2TP

(RFC 3193)

3G and 2G users

MPLS

Backbone

LAC

GGSN

Native

L2TP

Users mapped into

corporate VPNs

VRFs

PE

Corp HQ CE

GE VLAN


MPLS

Backbone

WiFi secured access 802.1/EAP option

WiFi User with

EAP/802.1x client

eg- WinXP, iPass,

Odyssey..

Access

Controller

BRAS

Any Backhaul

Transport

RADIUS EAPoL

802.1x

Policy

Server

EAP/RADIUS

EAP

AP

Note- DHCP happens after EAP authentication


Option - Authentication using 802.1X and EAP on 802.11 - overview

RADIUS

Server

EAPOW-Start

EAP-Response/Identity

Radius-Access-Challenge

EAP-Response (credentials)

Access blocked

Association

Radius-Access-Accept

EAP-Request/Identity

EAP-Request

Radius-Access-Request

Radius-Access-Request

RADIUS

EAPOW

802.11 802.11 Associate-Request

EAP-Success

Access allowed EAPOW-Key (WEP..)

802.11 Associate-Response

Source:

Microsoft


EAP/802.1x WiFi access

Pros

• EAP/802.1x built into WinXP

• Flexible authentication architecture – many different EAP options eg- GSM SIM using EAP/SIM, EAP-MD5, LEAP, Smartcards etc…

• Can handle interAP roaming with 802.11f

• Adopted in the corporate market

Cons:

• Doesn’t address core network / VPN portion, just secures access layer

• Today uses session keys vs temporal (WPA, coming in 802.11i)

• Need smarts to keep per user control in the network without double logon


Maintaining subscriber control when using 802.1x/EAP environment

“RADIUS relay” concept

802.1x access points have Radius client, EAP messages encapsulated in Radius messages

Host MAC address in the calling-station-attribute

Radius relay (BRAS) uses @domain name to forward Radius request to an external EAP capable Radius proxy or server

BRAS relay stores Host MAC address (and maybe user) and awaits authorization data (VR to use, IP pool/address to use, filters, etc)

DHCP request, based on the host MAC address, creates subscriber interface in proper context allocates IP address, assign default policies. Policy server control with no Web login

Access point creates Radius authentication and accounting (stop)

Radius Relay

DHCP

802.1x AP

Any Backhaul

Transport

Policy

Server

RADIUS

Server


Summary

Which access model?

• PPPoE is nice, but often not practical

• DHCP – web login models now can provide good per user control, and location info etc

Where am I? Location information

• Key for WiFi business models eg- generate content based on location (virtualised)

Security

• IPSEC is a good end-end mechanism, integration with VPNs

• EAP is flexible and useful in access, but needs to tie in with core network and per user control


Thank you…!

Contact: [email protected]

mailto:[email protected]


802.11 variants

802.11a 5.4MHz, OFDM, 54 Mbps, 10+ channels

802.11b 2.4GHz, DSSS, 11 Mbps, 3 channels

802.11d Enhancements to meet country specific regulations

802.11e Quality of Service

802.11f Inter-Access Point Protocol, handover between close APs

802.11g 2.4GHz, OFDM, 54Mbps, 3 channels

802.11h Specifically for 5GHz; power control and frequency selection

802.11i Security framework, reference to 802.1x and EAP

See PowerPoint comments page below for more details


Wireless LAN Technologies

802.11b 802.11a HiperLAN2

2.4 GHz

Public 5 GHz / Public / Private 5 GHz

Worldwide US/AP Europe

1-11 Mbps 20-54 Mbps (1-2 yrs)

100+ Mbps (future) 20-54 Mbps (1-2 yrs)

Freq. Band

Coverage

Data Rate

802.11g

2.4 GHz

Public

Worldwide

1-54 Mbps


PWLAN and Security

WEP encryption (Wireless Equivalent Protocol) much criticized in enterprise

• Also it uses static keys which is not valid for PWLAN as keys would need to be published

802.1x and EAP delivers improved security for PWLAN

• Introduces dynamic keys at start of session, and PWLAN sessions are short lived (unlike enterprise)

802.11i

• Uses 802.1x which uses EAP and allows dynamic keys

• Firmware upgrade for TKIP then hardware upgrade for improved AES encryption

• Poses transition complexity for existing user base

WPA (Wi-Fi Protected Access) is an interim step to 802.11i

• Uses 802.1x and EAP and TKIP but no AES


802.1x Overview Make up for deficiencies in WEP which uses static keys

IEEE 802.1x-2001: Port-Based Network Access Control

• Prior to authentication traffic is restricted to the authentication server

RFC 2284 (1998): PPP Extensible Authentication Protocol (EAP)

• EAP encapsulated in Radius for transport to EAP enabled AAA server

• Many variations EAP/TLS and EAP-PEAP supported by Microsoft, MD5, OTP, LEAP (Cisco), and SIM (GSM Subscriber Identity Module)

IEEE 802.11i Framework Specification

• Specifies use of 802.1x and EAP for authentication and encryption key

• New encryption in access point

• Access Points need firmware upgrade to TKIP then new hardware for AES


PWLAN and Mobile

3GPP standards org defined five scenarios for PWLAN integration with 3G

• From common authentication to seamless handover of voice service

• Specified 802.1x based authentication

• Part of 3GPP Release 6, specified in TS 23.234

But, real deployments are occurring well in advance of 3GPP R6……so:

GSM Association WLAN Task Force issued guidelines for pre Release 6

• Wed based login initially transitioning to 3GPP release 6 spec

A SIM located in WLAN cards will use authentication based on EAP/SIM

• Eg- Use of SIM dongle

EAP to SS7 gateways will allow mobile HLR / HSSs to authenticate the WLAN card


Authenticating against the GSM HLR

Existing database with all mobile subscriber information

Existing provisioning and customer care systems are used

EAP/SIM can offer GSM equivalent authentication and encryption

Gateway between RADIUS/IP and MAP/SS7 is required

• Eg Funk Software Steel Belted Radius/SS7 Gateway

• Ulticom Signalware SS7 software

• Sun server E1/T1 interface card

• An overview of the product is in this attachment:

• Major vendors Ericsson, Siemens, Nokia all have or are developing their own offer


802.1x EAP/SIM authentication from HLR Transparent RADIUS relay

BRAS AC,

(RADIUS Relay) Authenticator

RADIUS/SS-7

GW HLR

EAPoL RADIUS

RADIUS Gr Interface

DHCP Discover

Client

DHCP Request

DHCP Offer

DHCP Ack {address = End

User address from GGSN}

Client -

Authentication

Client –

IP Address

Assignment

GW HLR MAP

SS7


Tight integration proposed by 3GPP

GGSN Access Controller,

RADIUS Relay Authenticator RADIUS/SS-7

GW HLR

EAPoL RADIUS

RADIUS Gr Interface

Create PDP Context {IP, transparent mode APN,

IMSI/NSAPI, MSISDN, dynamic address requested}

Create PDP Context Response {End User Address}

DHCP Discover

Client

DHCP Request

DHCP Offer

DHCP Ack {address = End User

address from GGSN} Lease

expiration

Delete PDP Context Request

Client -

Authentication

Client –

IP Address

Assignment

GGSN

HLR

GPRS Tunneling Protocol


Real time handover…

Many access types – WLAN, 3G, GPRS…

Mobile IP could provide reasonable real-time macro roaming between cellular and WLAN access types (also alternates such as 802.16/WiMax)

Supported for dual mode CPE/handsets

• Eg- Dual Mode NEC cellphone with WLAN as trialed in DoCoMo

• PDAs with WLAN and CDMA 1x/EVDO or GPRS/WCDMA

• Notebooks with cellular data or dual mode cards

Off the shelf client software available today – IPUnplugged, Birdstep

Challenges- VoIP, WLAN automated logon (eg- 802.1x could solve this), applications/OS can handle address changes


Overview of Mobile IPv4 (RFC2002)

1. MN discovers Foreign Agent (FA)

2. MN obtains COA (FA - Care Of Address)

3. MN registers with FA which relays registration to HA

4. HA tunnels packets from CN to MN through FA

5. FA forwards packets from MN to CN or reverse tunnels through HA (RFC3024)

HA FA

1. and 2. 3.

MN

CN

5. 4.

Internet


Mobile IP Interworking with UMTS/GPRS

Recommends use of FA Care Of Addresses (CoA), not collocated, to conserve IPv4 addresses

Source:

3GPP


Registration Process to GGSN FA

5. Activate PDP

Context Accept

(no PDP address)

4. Create PDP

Context Response

(no PDP address)

2. Activate PDP

Context Request

( APN=MIPv4FA )

IPv4 - Registration UMTS/GPRS + MIP , FA care-of address

TE MTHome

NetworkSGSN GGSN/FA

3. Create PDP

Context Request

( APN=MIPv4FA )

6. Agent Advertisement

7. MIP Registration Request

9. MIP Registration Reply

10. MIP Registration Reply

1. AT Command (APN)

8. MIP Registration Request

A. Select suitable GGSN


Overview of Mobile IPv6 Removes need for external FA in future 3GPP systems

1. MN obtains IP address using stateless or stateful autoconfiguration

2. MN registers with HA

3. HA tunnels packets from CN to MN

4. MN sends packets directly to CN or via tunnel to HA

• Binding Update from MN to CN removes HA from path.

HA

1. 2.

MN

CN

4. 3.

Internet

Documents

WiFi Hotspot Service Control - docshare01.docshare.tipsdocshare01.docshare.tips/files/23572/235722830.pdfTerminate PPP session into VR/VRF or ... • Adopted in the corporate market