Overview of IEEE 802 11 Wireless LANs

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Overview of IEEE 802. 11 Wireless LANs - WLAN & IP Protocol Interoperability Juha Ala-Laurila Nokia Mobile Phones juha. ala-laurila@nokia. com 1 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL

Presentation Outline • WLAN Technology Update • Standards/Competition • IEEE 802. 11 WLAN Standard • What is defined by standard • IEEE 802. 11 functions in TCP/IP model • Connecting WLANs as part of IP infrastructure • Interworking problems • Integration (security, mobility, Qo. S, …) • Need for advanced IP roaming protocols • Conclusions 2 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL

Wireless IP Networking Revolution Past Paradigms Fixed Data Present Demand Local Area WLAN - On campus Unlicensed Bands - At home Mobility with Network Connectivity Mobile Voice 3 © NOKIA Future Solutions (Data + Voice) IETF IAB Wireless Workshop 29. 2. 00/JAL • • Personal mobility High data rate Incremental infrastructure Start 1998 “ 3 G” WCDMA Wide Area Licensed Bands - On the road • • Full mobility Modest data rate All new infrastructure Start 2001

WLAN Dream Finally Seems to Happen. . . • Recently lots of serious WLAN activities have been announced • • • Big players have invested in WLAN (Cisco, Intel, Nokia) Integrated WLAN solutions appearing (Apple) Even IETF is planning "meeting WLAN rules" • Wireless IP solutions have lots of momentum! • People desire wireless IP terminals and access devices • WLAN offers a good mobile solution for indoor IP access • • Added value for the user - Flexibility, user mobility Added value for ISP - solution for public high IP access • WLAN standards are converging - IEEE 802. 11 b rules • 4 © NOKIA Interoperability has been the main obstacle IETF IAB Wireless Workshop 29. 2. 00/JAL

WLAN Standards Evolution 2. 4 GHz (BW 80 MHz) 1996 Proxim Open. Air FH 1. 6 Mb/s 1997 IEEE 802. 11 FH 1, 2 Mb/s 1999 Home. RF FH 1. 6 Mb/s IEEE 802. 11 DS 1, 2 Mb/s IETF IAB Wireless Workshop 29. 2. 00/JAL IEEE 802. 11 b HR 1, 2, 5. 5, 11 Mb/s IEEE 802. 11 a 9 -54 Mb/s IEEE 802. 11 standard extensions - tbd 2000 © NOKIA ETSI BRAN H 1 23 Mb/s WLAN products 1998 5 5 GHz (BW 450 MHz) ETSI BRAN H 2 9 -54 Mb/s

WLANs: Exploitation Scenarios 54 Mb/s Wireless Multimedia BRAN HIPERLAN 11 Mb/s IEEE 802. 11 b Direct-Sequence dominates in products 802. 11 DS HS 5, 5 Mb/s Serial Cable Replacement 802. 11 DS HS (5. 5 Mb/s mode) 2 Mb/s Wireless Local Area Coverage 802. 11 DS & FH 1 Mb/s 500 kb/s BT 10 m 6 © NOKIA 30 m 60 m IETF IAB Wireless Workshop 29. 2. 00/JAL 100 m 200 m > 400 m

What Does WLAN Standards Define? 7 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL

ISO Model Applied to the LAN world Application Presentation Session LLC provides traditional HDLC type protocol MAC controls access to the physical channel according to a predetermined set of rules Transport Network Datalink Physical 8 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL Logical Link Control (LLC) Medium Access Control (MAC) Main differences: • Radio link unreliable • Higher error rate • Eavesdropping risk • All traffic goes via access point

IEEE 802. 11 MAC Overview IP Packets MAC Layer Management Entity (MLME) MAC DSAP radio mgmt e. g. scanning association management Fragmentation & ARQ power management shared-key authentication WEP (RC 4) encryption management info base (MIB) addressing framing • 48 bit MAC address • Ethernet compliant • Unique identifier • Multicast & bcast support 9 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL • Retransmission, error correction • Radio link security • Data authentication • Data encryption • Simple scrambling • Peer-to-peer CSMA/CA channel access PHY SAP • Radio link Qo. S • Dedicated real-time support with PCF

WLAN - Plain Wireless Ethernet Extension Application Level Data Applications TCP/IP stack Other LAN interface 10 © NOKIA 802. 11 WLAN radio Application Seamless support for fixed IP features essential! addressing, routing Network Bridge control 802. 11 WLAN Ethernet radio IETF IAB Wireless Workshop 29. 2. 00/JAL IP routing Ethernet TCP/IP Ethernet

The Design Challenges are. . . … The roaming IP devices with changing IP address, service location and service provider …IP backbone and access networks have not been designed for moving terminals. . . Radio link is vulnerable for security attacks and Qo. S deterioration 11 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL

Typical Obstacles for IP Roaming. . . How to authenticate the user ? How can I get IP address How to protect corporate data? How can I have secure connection? How to find Roaming services, printer? WLAN User How to bill the user? Public ISP 12 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL Internet Corporate LAN Firewall IT manager

Problems to Be Solved • Terminal Mobility in the IP network • • WLAN solves LAN level mobility but. . . How to support mobility between IP sub-networks • Security Issues • User authentication and billing • End-to-end data security and remote access • Configuration and Service discovery • How to know essential network parameters • How to locate services in a new network • Wireless Quality of Service • How to map IP Qo. S classes into radio link • TCP behavior is not optimal in wireless world 13 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL

Client appl Security Components. . . Host Optional end-to-end Data Encryption -> Privacy Access Controller TCP/IP stack IP packet encryption / authentication 802. 11 WLAN offers radio link packet authentication and data encryption (RC 4) WLAN AP WLAN encryption • Key management and PKI needed TCP/IP for secure ad-hoc stack networking • IPSEC aware Qo. S • IPSEC and IKE used for security critical access • IPSEC policy mngt should be defined • AAA needed for global roaming • Remote access IPSEC needed 14 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL

Multiple Authentication Needed. . . Global AAA & PKI architecture for roaming Banks etc. Internet AAA server Service provider authentication WLAN network ISP Network WLAN terminals with integrated smart card reader 15 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL • Authentication done in company / ISP AAA server. • Smart cards supported • Standards to support several AAA mechanisms Local AAA server ISP service authentication

Essential WLAN Mobility Support… DHCP server (Xx. x) Sub-network A Access Point A Sub-network B DHCP server (Yy. y) Access Point C Access Point B WLAN terminal IP = Y. y. y) WLAN terminal IP = X. x. x) • IEEE 802. 11 defines LAN level (AP-2 -AP) mobility • Forward handover • Same IP address stays 16 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL MOBILE IP may complement WLAN mobility functions and enable full WLAN mobility with min. latency

Wireless Quality of Service in WLANs Current WLAN devices mostly used for best effort data transmission, but later in the future… … WLANs should support also wireless voice -> radio link Qo. S is essential … Operators would like to apply traffic based billing -> Qo. S support needed 17 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL

Findings Related to Qo. S and Vo. IP • NAT is a real problem as it breaks Qo. S reservations • Vo. IP DOES NOT WORK WITH NAT -> goes beyond all Qo. S problems!!! • IPv 6 would be natural solution • RSVP is complex -> hard to adopt • Diffs seems best solution for wireless IP link • Straightforward mapping • Wireless TCP problem and header compression needs to be studied and standardization efforts are to be expected 18 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL

Mapping IP Qo. S into Radio Link Application Data IP Packet RSVP Differentiated Services Packet filters DS-field (or TOS-octet) (8 bits) Ethernet Frame Ethernet priority (3 bits) Wireless link Radio queues Real-time queue Best-effort data Vo. IP Realtime All the rest Best Effort WLAN Qo. S resembles 802. 1 p&Q approach: - Separate radio link queues and priority scheduling - IP packet filters and Diffs bits define the queue 19 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL

Layered View: Native IP Interworking Applications IP routing & Qo. S IP level authentication (AAA + PKI) IP (+ IP mobility? + IP security? + IP/GPRS billing? ) Seamless Interworking WLAN security WLAN mobility WLAN Radio Access 21 © NOKIA PCF IETF IAB Wireless Workshop 29. 2. 00/JAL PPP security 802. 1 p/Q Fixed Ethernet

Hmm. . . How Does This Fit into Future Cellular Mobility Management? 1) 3 G & WLAN Integration 2) 3 G & WLAN Interworking Focus on authentication and mobility 22 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL

3 G & WLAN integration Internet Summary of features: - Integrated authentication and billing - WLAN security and mobility with IP terms - AAA work is a must!!! 3 G/"HLR" Gateway "WLAN GGSN" GGSN SGSN Access Router WLAN RAN 3 G/GPRS RAN WLAN AP BTS Multimode terminal with 3 G user identity 23 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL

Summary and "Wishes" for IETF • WLANs first implemented as wireless IP extensions, WLAN cellular interworking possible later • IEEE 802. 11 b is "leading" standard • WLANs should support data and Vo. IP services -> avoid NAT • Global IP mobility and AAA infrastructure are missing pieces of IP roaming • IPv 6 solves most of the listed obstacles with native mobility and security -> should be adopted • IETF standardization should consider the requirements of roaming and ad-hoc networking 25 © NOKIA IETF IAB Wireless Workshop 29. 2. 00/JAL End-to-end security AAA for roaming IPv 6? ? Global IP mobility Common Mission for all Wireless IP New WLAN Related technologies Vo. IP + Qo. S standards mechanisms Wireless Global IP Infrastructure