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WiFi Hotspot Service Control Design & Case Study Overview PowerPoint Presentation
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WiFi Hotspot Service Control Design & Case Study Overview

WiFi Hotspot Service Control Design & Case Study Overview

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WiFi Hotspot Service Control Design & Case Study Overview

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  1. WiFi Hotspot Service ControlDesign & Case Study Overview Simon Newstead APAC Product

  2. Agenda • Overview of different access models • Identifying the user location • Secure access options • Case studies (as we go)

  3. WiFi control - access modelsPPPoE RADIUS PPPoE connection MPLS Backbone Layer 2 Backhaul Transport (Bridged1483, Metro E) Access Controller BRAS LNS* WiFi User with PPPoE client (WinXP or 3rd party) Policy Server AAAA Terminate PPP session into VR/VRF or tunnel on via L2TP Fine grained QoS / bandwidth control Dynamic Policy Enforcement (COPS) Lawful Intercept etc…

  4. 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

  5. PPPoE access modelCase Study – Japanese Provider Hotspot AP RADIUS ATM Bridged 1483 ISP VR Bridging DSL modem Backbone WiFi Users with PPPoE client WiFi VR WiFi operator network Access Controller BRAS Bridging DSL modem DSL Users with PPPoE client Mapping of user to VR based on RADIUS, domain mapping

  6. WiFi control - access modelsDHCP model – Web Login External DHCP Server* DHCP MPLS Backbone Layer 2 or Layer 3 Backhaul (any) Access Controller BRAS WiFi User with inbuilt DHCP client. Policy Server / Web Login Server DHCP Server or Relay* Initial policy route to Web logon server Fine grained QoS / bandwidth control Dynamic Policies (COPS) Accounting Lawful Intercept etc…

  7. 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)

  8. 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

  9. How it works - Step One • User opens up webbrowser and triesto go to Google • Session directedto captive portal on policy server • Choice to entermobile phone number or username andpassword • Mobile phonenumber entered

  10. Step Two • One-time passwordsent via SMS touser’s mobilephone • Received password entered into portal page

  11. Step Three • Upon successfulauthentication,captive portal isreleased and original webdestination isloaded. • Mini-logout window to facilitate signoff. • Usage billed to user’s mobile phone bill once finished

  12. Dynamic Policies • 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)

  13. 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 Subscriber Interface A IP Demux Rate Limit Internet to 512k Subscriber Interface B IP Demux Rate Limit Internet to 2M Prioritise VoIP to strict priority queue Add firewall policies User A: L3 Switch VLAN 101 User B: Access Controller BRAS

  14. Generic Web Login process Weblogin - Policy Server Radius DHCP relay point Access ControllerBRAS RoutingLayer Upstream Router AP Switch Layer FE GE GE GE inbuilt DHCP server WEB login sequence 1. IP assignments through DHCP & subscriber interface come up – Dynamic SI 2. HTTP redirected and show the portal web page 3. Input subscriber ID and password 4. Radius authentication 4. Download policies Internet & service access WEB logout sequence 1. (Access the portal & click on logout button) or (DHCP lease expired) 2. Radius accounting 2. (Reset policies) or (Delete subscriber interface) – Dynamic SI

  15. 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 – Train Station Portal - Free access to timetables, fares.. Access ControllerBRAS Portal - Free sports news.. Hotspot – Cafe Weblogin - Policy Server

  16. 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)

  17. Side topic – routing back to WiFi userin 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…

  18. 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

  19. WiFi secured accessIPSEC option RADIUS L2TP/IPSEC connection (RFC3193) MPLS Backbone Any Backhaul Transport Access Controller BRAS LNS* WiFi User with inbuilt IPSEC client Eg- Win2k, WinXP Policy Server Terminate IPSEC BRAS control of PPP session

  20. 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?)

  21. IPSEC WiFi accessJapan 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: Corp HQ CE Users mapped into corporate VPNs PE GE VLAN IPSEC / L2TP (RFC 3193) MPLS Backbone WiFi User with native Windows Client NativeL2TP VRFs LAC GGSN Access Controller- BRAS (PE) 3G and 2G users

  22. WiFi secured access802.1/EAP option EAP EAPoL802.1x EAP/RADIUS RADIUS MPLS Backbone Any Backhaul Transport AP Access Controller BRAS WiFi User with EAP/802.1x client eg- WinXP, iPass, Odyssey.. Policy Server Note- DHCP happens after EAP authentication

  23. Association Access blocked 802.11 Associate-Request EAPOW-Start 802.11 Associate-Response EAP-Request/Identity Radius-Access-Request EAP-Response/Identity Radius-Access-Challenge EAP-Request Radius-Access-Request EAP-Response (credentials) Radius-Access-Accept EAP-Success Access allowed EAPOW-Key (WEP..) Option - Authentication using802.1X and EAP on 802.11 - overview RADIUSServer 802.11 RADIUS EAPOW Source: Microsoft

  24. 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

  25. 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 thehost 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) Policy Server DHCP RadiusRelay Any Backhaul Transport RADIUS Server 802.1x AP

  26. 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

  27. Thank you…! Contact:

  28. 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

  29. Wireless LAN Technologies 802.11b 802.11g HiperLAN2 802.11a Freq. Band 2.4 GHz Public 2.4 GHz Public 5 GHz 5 GHz / Public / Private Coverage Worldwide Worldwide Europe US/AP Data Rate 20-54 Mbps (1-2 yrs) 100+ Mbps (future) 1-11 Mbps 1-54 Mbps 20-54 Mbps (1-2 yrs)

  30. 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

  31. 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

  32. 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

  33. 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

  34. RADIUS 802.1x EAP/SIM authentication from HLRTransparent RADIUS relay MAPSS7 GW HLR BRAS AC, (RADIUS Relay) RADIUS/SS-7 GW HLR Client Authenticator EAPoL RADIUS Gr Interface Client - Authentication DHCP Discover DHCP Offer Client – IP Address Assignment DHCP Request DHCP Ack {address = End User address from GGSN}

  35. Access Controller, RADIUS Relay RADIUS/SS-7 GW HLR Client Authenticator EAPoL RADIUS Gr Interface Client - Authentication Create PDP Context {IP, transparent mode APN, IMSI/NSAPI, MSISDN, dynamic address requested} Create PDP Context Response {End User Address} DHCP Discover RADIUS Client – IP Address Assignment DHCP Offer DHCP Request DHCP Ack {address = End User address from GGSN} Lease expiration Delete PDP Context Request Tight integration proposed by 3GPP HLR GPRS Tunneling Protocol GGSN GGSN

  36. 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

  37. 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) CN 5. 4. FA HA Internet 1. and 2. 3. MN

  38. Mobile IP Interworking with UMTS/GPRS • Recommends use of FA Care Of Addresses (CoA), not collocated, to conserve IPv4 addresses Source: 3GPP

  39. Registration Process to GGSN FA

  40. Overview of Mobile IPv6Removes need for external FA in future 3GPP systems CN • 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. 4. 3. HA Internet 1. 2. MN