Introduction Wireless Networking Wireless Networking Topologies Module-05B

1. Introduction Wireless Networking Wireless Networking TopologiesModule-05B Jerry Bernardini Community College of Rhode Island Wireless Networking J. Bernardini

2. Presentation Reference Material • CWNA Certified Wireless Network Administration Official Study Guide (PWO-104), David Coleman, David Westcott, 2009, Chapter-7 • The California Regional Consortium for Engineering Advances in Technological Education (CREATE) project Wireless Networking J. Bernardini

3. Network Topologies • Topologies are physical or logical layouts of nodes • Topology-How things are interconnected • Basic Networking Topologies - Bus Ring Star Mesh • Wireless Topologies are based upon coverage area • Wireless wide area networks (WWAN) • Wireless metropolitan area networks(WMAN) • Wireless personal area networks (WPAM) • Wireless local area networks (WLAN) Wireless Networking J. Bernardini

4. Wireless Wide Area Networks (WWAN) • Networks with ten’s of miles of coverage • Wireline WANs • T1, Frame Relay, ATM, MPLS • WLANs • Cellular, T-Mobile, Verizon • GPRS, CDMA, TDMA, GSM technologies • Wireless point-to-point networks • IEEE 802.11 was not designed for WWAN Wireless Networking J. Bernardini

5. Wireless Metropolitan Area Network (WMAN) • Networks with miles of coverage • Networks for metropolitan areas • Around Washington DC • Around Boston • DC government network • WMAN technologies • IEEE 802.16 • WiMAX • Can provide “the last mile” coverage Wireless Networking J. Bernardini

6. Wireless Personal Area Network (WPAN) • Networks with feet (meters) of coverage • Between Laptops • Between PDAs • Between wireless phones • Headsets • Technologies used • Bluetooth • Infrared • ZigBee • Radio • FHSS Wireless Networking J. Bernardini

7. Wireless Local Area Network (WLAN) • Networks with hundred’s of feet of coverage • Provides end user access to LANs • Coverage for buildings and campuses • Great fit for 802.11 technology • 802.11 WLAN provides balance of: • Performance • Cost • Availability • Technology evolution Wireless Networking J. Bernardini

8. IEEE 802.11 Topologies • The purpose of 802.11 is to interconnect radio cards • Every wireless device has a radio card • All wireless devices are referred to as Stations (STA) • Three topologies defined by 802.11 – Service Sets • Basic Service Set (BSS) • Extended Service Set (ESS) • Independent Basic Service Set (IBSS) • Nonstandard Topologies • Bridging, Repeating, Workgroup bridging • Mesh networking (growing in importance) Wireless Networking J. Bernardini

9. Network Communication Modes • Modes or how STAs can communicate • Simplex Communications • One STA transmits, one STA receives • One way communications • Half-Duplex Communications • Both STAs can transmit and receive but not at the same time – must take turns • Walkie-talkies • 802.11 networks • Full-Duplex Communications • Both STAs can transmit and receive at the same time • Requires two radio channels • 802.11 does not support full-duplex Wireless Networking J. Bernardini

10. Basic 802.11 Components • Wireless Client stations or Wireless devices –STAs • Wireless Access Points - APs • Wireless Bridges • Wireless Repeaters • Wireless Controllers Wireless Networking J. Bernardini

11. Access Points • The Access Point (AP) is the device that provides access to the WLAN • Each BSS has one AP and multiple Aps make an ESS • Two categories of APs are Fat and Thin Access Points • Thin AP’s are paired with a wireless LAN switch or controller to offer additional functionality and centralization over Fat AP’s. • Fat (Thick or Smart) AP’s are "fat" because they operate autonomously as members of a decentralized WLAN. 3Com Wireless LAN Switch WX1200 3Com AP3750 MAP

12. Access Points Market Belkin APs Buffalo APs Linksys APs Cisco APs Wireless Networking J. Bernardini

13. Autonomous or FAT Access Points • Traditional wireless LANs use decentralized Fat access points • Manual configuration required to set the power level, channel, security and other configurable parameters. • Each access point is individually configured • Third party software solutions are often needed for additional security and management capabilities • For large networks which quickly add to the total cost of ownership. Wireless Networking J. Bernardini

14. Autonomous AP Implementation Wireless Networking J. Bernardini

15. Lightweight or Thin Access Points • Centralized WLANs use a wireless controller to manage, process, and configure the RF environment • Centralized WLANs use called thin or lightweight APs • APs communicate directly with the central controller with the wired network • All the functionality and intelligence is offloaded to the controller • This provides a single point of administration for various policies relating to security, intrusion detection, user roles, and software upgrades.. Wireless Networking J. Bernardini

16. Thin Access Points Implementation Wireless Networking J. Bernardini

17. Access Point Modes • APs are small computers with one or more radios • The AP operating systems are Linux or propriety • IEEE 802.11 defines three Operational Modes • Root Mode • The default mode for most APs • Provides wireless clients access to the WLAN • Bridge Mode • Used to create a link between two or more APs • Repeater Mode • Used to extend the range of a WLAN beyond normal boundaries Wireless Networking J. Bernardini

18. Access Point Features • Support of various IEEE 802.11 standards • FHSS, DSSS, OFDM, 802.11a,b, g, n • Support for various security standards • IEEE 802.11i, WEP, WPA, WPA2, PSK, RADIUS • Support for QoS extensions • Wireless Multimedia (WMM), VoWLAN • Fixed or Detachable Antenna • Omni-directional, Directional • Filtering • MAC, Protocol • Variable Power • Percent of Max or Actual Levels Wireless Networking J. Bernardini

19. Power Over Ethernet (PoE) Support • Found on Enterprise and not on SOHO APs • Primary benefit is ability to install APs where no AC power is present • IEEE 802.3af standard for PoE • PoE is supply by injectors or switches Wireless Networking J. Bernardini

20. PoE Options and Power Source Equipment(PSE) Active/PSE Switch PD Access Point Pins 4-5 +Power(48v) Pins 7-8 –Power 1 DC Power CAT-5e Ethernet PD Access Point 2 Switch AC Power DC Power CAT-5e Ethernet PSE Injector Access Point DCPower 3 Switch AC Power DC Power CAT-5e Ethernet PSE Injector Tap/Splitter

21. Wireless Bridges • Provides a link between two WLAN segments • Not full described by IEEE 802.11 • Vendor dependent • Two Modes – Root and Non-root Point-to-Point Root Non-Root Non-Root Root Non-Root Point-to-Mulitpoint

22. WLAN Bridge Modes and Components • Root Mode – A bridge that acts as the hub to a group of bridges. • Only One Root-Bridge for PtP or PtMP links (important for tests) • For PtP link one Root-Bridge and one Non-Root Bridge • Non-Root Mode – A member bridge of a group that is not the Root Bridge. • Can also function as a standard AP • Can function as a repeater 3Com WLAN Bridge Proxim Quick Bridge 11 Cisco Aironet 1400

23. Richardson Elementary Yagi Weaver- Special Education Dish Roberts Middle School Dish High School 2 Bridges One 12 dBi omni One Dish Administration 2 Bridges One 12 dBi omni One Yagi Channel #1 Channel #6 Bolich Middle School Yagi Channel #11 Price Elementary Yagi Dewitt Elementary Yagi Bridge Application: School District Bode Elementary Yagi Lincoln Elementary Yagi

24. Residential WLAN Gateways • Same as SOHO wireless routers • Support of various IEEE 802.11 standards • FHSS, DSSS, OFDM, 802.11a,b, g, n • Support for various security standards • IEEE 802.11i, WEP, WPA, WPA2, PSK, RADIUS • Built in firewall features • Packet and MAC Filtering • Switched Ethernet ports • DHCP • NAT and PAT Wireless Networking J. Bernardini

25. Enterprise WLAN Wireless Networking J. Bernardini

26. Enterprise Wireless Gateways • Enterprise Wireless Gateway – is a powerful device that interfaces between the enterprise network and the corporate firewall. • HTML  WML • Authentication, Filtering, and Security • Traffic Management, QoS • Mobile Addressing Vernier IS 6500p BlueSecure ControllerBSC 2100

27. Internet Enterprise Wireless Gateways Enterprise Server Enterprise Gateway Router Switch Access Points Wireless Clients

28. Voice Over IP WLAN (VoWLAN) • Telephone communication using a WLAN requires latency and QoS considerations • Special equipment is required • VoWLAN phone (phones that will connect to WLAN) • WLAN infrastructure with QoS (low latency and Protocol management) • Call management (PBX for IP phones) • Voice gateway for outside calls • IP phones associate with APs rather than cellular towers Linksys Siemens Wireless Networking J. Bernardini

29. Client Stations and Adapters Wireless Networking J. Bernardini

30. Service Set Identifiers - SSID and BSSID • SSID -Service Set Identifier is a 1-32 byte alphanumeric sequence that uniquely names an ESS (the network name). • Any SSID or Null SSID is a blank SSID used to associate with anyone. • BSSID- Basic Service Set Identifier is a 48-bits that uniquely identifies a BSS AP Wired LAN BSA Basic service Area –Physical Coverage Area ESS Id = SSID BSS Id = BSSID

31. Basic Service Set (BSS) BSS - The Basic Service Set is a term used to describe the collection of Stations which may communicate together within an 802.11 WLAN. • Basic Service Set (BSS): Group of wireless devices served by single AP • infrastructure mode • BSS must be assigned unique identifier • Service Set Identifier (SSID) • Serves as “network name” for BSS • Basic Service Area (BSA): Geographical area of a BSS • Max BSA for a WLAN depends on many factors • Dynamic rate shifting: As mobile devices move away from AP, transmission speed decreases

32. Basic Independent Basic Service Set (BSSID) • Independent Basic Service Set (IBSS): Wireless network that does not use an AP • Wireless devices communicate between themselves • Peer-to-peer or ad hoc mode • BSS more flexible than IBSS in being able to connect to other wired or wireless networks • IBSS useful for quickly and easily setting up wireless network • When no connection to Internet or external network needed

33. Extended Service Set (ESS) • ESS - is comprised of a number BSS’s • ESS stations must have the same SSID • The BSSID is the “name” of the BSS (not same as SSID) • APs can be positioned so that cells overlap to facilitate roaming • Wireless devices choose AP based on signal strength • Stations going from one BSS to another will deal with Handoff ESS SSID Wired LAN BSS2 (BSSID2) BSS3 (BSSID3) BSS1 (BSSID1)

34. Wireless Mesh Access Points • Mesh APs associate with multiple APs • Association between APs is limited by vendor (3-5) • Currently vendor dependent • Clients can reach destinations thru multiple APs • APs route packets to ovoid failures and optimal paths • Mesh Networks are more resilient • Not every AP has to be connected to a wired network • Self-Healing, Self-Configuring using Layer-2 Protocol • New standard IEEE 802.11s will allow interoperability between vendors Wireless Networking J. Bernardini

35. Wireless Mesh Network Implementation Wireless Networking J. Bernardini

36. Reassociation Wired LAN Access Points 1 2 Reassociation Request 1 Link Fading Wireless Clients

37. Load Balancing or Sharing Wired LAN Access Points 1 2 2 2 1 1 Wireless Clients 1 2

38. WLAN IP Addressing • In standard networking, IP protocol responsible for moving frames between computers • Network layer protocol • TCP/IP works on principle that each network host has unique IP address • Used to locate path to specific host • Routers use IP address to forward packets • Prohibits mobile users from switching to another network and using same IP number • Users who want to roam need new IP address on every network

39. Infrastructure Mode CWNA Guide to Wireless LANs, Second Edition

40. Channel reuse CWNA Guide to Wireless LANs, Second Edition

41. Flip flop between access points CWNA Guide to Wireless LANs, Second Edition

42. WLAN Design Models • Point-to-Point (PtP) • Point-to-Multipoint (PtMP) Wireless Networking J. Bernardini

43. WLAN Modes • Single MAC Model • Edge, Autonomous, Stand-Alone, Fat-AP • Split MAC Model • Centralized, Thin-AP • Mesh Network • Distributed, Multipath, IEEE 802.11s Wireless Networking J. Bernardini

44. Single MAC Model Wireless Networking J. Bernardini

45. Split MAC Model Wireless Networking J. Bernardini

46. WLAN Model Evolution • Intelligent Edge(Distribution) • Quick to setup but for small-medium networks • Difficult to mage for large networks • WLAN Network Management Systems • Centralized Management Distribution Processing • For large networks • Centralized WLAN Architecture (Split MAC) • For large networks with centralized controller • Large amount of wiring needed • Distributed Data Forwarding (DDF) WLAN • Similar to Split MAC but uses Fat-AP • Unified WLAN Architecture • Wireless built in to every thing including switches Wireless Networking J. Bernardini

47. WLAN Power Management Features • Active Mode • No power saving but improved station and AP performance • For desktops and line powered laptops • Power Save Mode • Dozing and Wake modes • Switches to wake to check for frames • WMM Power Save • U-APSD Unscheduled Automatic Power-Save Delivery • This is an industry certification • IEEE 802.11e-2005 Wireless Networking J. Bernardini

48. Power Management • A WLAN laptop must remain “awake” in order to receive network transmissions • Original IEEE 802 standard assumes stations always ready to receive network messages • Power management: Allows mobile devices to conserve battery life without missing transmissions • Transparent to all protocols • Differs based on WLAN configuration • AP records which stations awake and sleeping • Buffering: If sleeping, AP temporarily stores frames

49. Power Management • At set times AP send out beacon to all stations • Contains traffic indication map (TIM) • At same time, all sleeping stations switch into active listening mode • Power management in ad hoc mode: • Ad hoc traffic indication message (ATIM) window: Time at which all stations must be awake • Wireless device sends beacon to all other devices • Devices that previously attempted to send a frame to a sleeping device will send ATIM frame indicating that receiving device has data to receive and must remain awake

50. Continuous Aware Mode • Constantly Awake Mode provides the best performance allowing the client a strong connection between the wireless card and the AP; however, it also rapidly drains the client’s battery, resulting in shorter battery life.