IS3120 Network Communications Infrastructure Unit 5 IEEE 802.11a/b/g/h/i/n Wireless LANs

Class Agenda 4/15/16 Learning Objectives Lesson Presentation and Discussions. Discussion on Assignments. Discussion on Lab Activities. Break Times as per School Regulations.

Learning Objective Align the wireless standards and security methodologies used to increase business productivity.

Key Concepts Overview of IEEE 802.11 wireless LAN standards and specifications IEEE 802.11 a/b/g/h/n IEEE 802.11 i and layered security strategies for WLANs Wireless LAN design: Wireless access points (WAPs) SSID broadcasting versus stealth RF site surveys Workgroup WLANs Broadband/backbone WLANs

EXPLORE: CONCEPTS

OSI Model and IEEE 802.11

Max. Data Rate in Megabits per Second (Mbps) Range (Indoor/ Outdoor) Comparing 802.11x Standards Standard Band (GHz) Max. Data Rate in Megabits per Second (Mbps) Range (Indoor/ Outdoor) in Feet 802.11a 5 54 115/390 802.11b 2.4 11 125/460 802.11g 802.11n 2.4 or 5 600* 230/820 * Typical rate is 144 Mbps

IEEE 802.11a Typical throughput in mid-20 Mbps 9/22/2018 IEEE 802.11a Typical throughput in mid-20 Mbps Uses a 52-subcarrier orthogonal frequency-division multiplexing (OFDM) Restricted almost to line of sight Cannot penetrate as far as 802.11b/g because it’s absorbed more readily (c) ITT Educational Services, Inc.

MULTIPLEXING Whenever the bandwidth of a medium linking two devices is greater than the bandwidth needs of the devices, the link can be shared. Multiplexing is the set of techniques that allows the simultaneous transmission of multiple signals across a single data link. As data and telecommunications use increases, so does traffic.

Figure 6.1 Dividing a link into channels

Figure 6.2 Categories of multiplexing

IEEE 802.11b The first wireless standard in use 9/22/2018 IEEE 802.11b The first wireless standard in use Less susceptible to corruption Uses Adaptive Rate Selection (ADS) Scales back as signal quality decreases Less susceptible to corruption due to interference and signal attenuation Uses the Complementary Code Keying (CCK) RF signal format. This is a slight variation on Code Division Multiple Access (CDMA ) that uses the basic Direct Sequence Spread Spectrum (DSSS ) as its basis. 1 Mbps 2 Mbps 11 Mbps 5.5 Mbps (c) ITT Educational Services, Inc.

IEEE 802.11g Most wireless adapters support 802.11g 9/22/2018 IEEE 802.11g Most wireless adapters support 802.11g Backwards-compatible with 802.11b Compatible with 802.11a if WAP broadcasts in both 2.4 GHz and 5 GHz ranges Incorporates OFDM to achieve higher data transfer rates Can scale back to 11 Mbps or lower (c) ITT Educational Services, Inc.

IEEE 802.11n Highly popular today 9/22/2018 IEEE 802.11n Highly popular today Backwards-compatible with 802.11a/b/g 40 MHz maximum channel bandwidth Supports up to 4 MIMO spatial streams Can interfere with: Other 802.11 systems using 2.4 frequency Non-802.11 systems such as Bluetooth (c) ITT Educational Services, Inc.

MIMO MIMO stands for multiple-input multiple-output, where multiple refers to multiple antennas used simultaneously for transmission and multiple antennas used simultaneously for reception, all over a radio channel.

IEEE 802.11h Amendment to IEEE 802.11 standard 9/22/2018 IEEE 802.11h Amendment to IEEE 802.11 standard Solves interference on the 5 GHz frequency band Defines how 802.11a devices implement: Dynamic Frequency Selection (DFS) Transmitter Power Control (TPC) (c) ITT Educational Services, Inc.

The Future: IEEE 802.11ac High throughput WLAN in the 5 GHz band 9/22/2018 The Future: IEEE 802.11ac High throughput WLAN in the 5 GHz band Multi-station WLAN throughput Minimum 1 Gigabit per second Maximum single link throughput of at least 500 Mbps 80 MHz and 160 MHz channel bandwidths Up to 8 MIMO spatial streams (c) ITT Educational Services, Inc.

SSID Broadcasting versus Stealth 9/22/2018 SSID Broadcasting versus Stealth SSID Broadcasting Stealth Mode Hi, I’m WGABLDG5! SSID Broadcasting Service Set Identifier (SSID) is the name you give your wireless network. Makes it easy for users to identify particular WAPs when deciding which WAP to connect to. A WAP transmits beacon frames, which includes the WAP’s SSID. Wireless nodes receive beacon frame, determine if they want to associate with the WAP transmitting the beacon. A wireless station transmits probe frames, which include its station ID and the SSID. You can map SSIDs to virtual LANs; thus, some APs support multiple SSIDs. Stealth Mode Stealth mode also known as closed mode, closed network, or private network. A stealth WAP or broadband Wi-Fi router hides itself by not broadcasting its SSID; the SSID doesn’t appear in wireless network lists. To connect to a stealth WAP or router, you must know the SSID and configure your device to access the WAP or router. Wireless Router Wireless Router (c) ITT Educational Services, Inc.

EXPLORE: PROCESSES

Site/RF Surveys Understand requirements Get diagram 9/22/2018 Site/RF Surveys Understand requirements Get diagram Inspect environment Assess environment Identify coverage area Determine WAP locations For an excellent step-by-step, see Jim Grier’s full instructions at http://www.wireless-nets.com/resources/tutorials/conduct_wireless_site_survey.html. 1. Understand wireless requirements. 2. Get a building diagram. 3. Visually inspect the environment. 4. Assess existing network environment. 5. Identify coverage area. 6. Determine preliminary WAP locations. (c) ITT Educational Services, Inc.

Design a WLAN Conduct RF survey and physical site assessment 9/22/2018 Design a WLAN Conduct RF survey and physical site assessment Assess type of users who will use WLAN Determine which applications users and administrators need Determine type of traffic that will use WLAN Map out core, aggregation, and access layers (c) ITT Educational Services, Inc.

Design a WLAN Create coverage map (if not done during RF survey) 9/22/2018 Design a WLAN Create coverage map (if not done during RF survey) Create security scheme Authorization, access control, encryption Route external connections through a firewall (c) ITT Educational Services, Inc.

Create Gap-Free WLAN Security 9/22/2018 Create Gap-Free WLAN Security Locate networking equipment in secure locations Install or check settings of firewalls, IDS/IPS, other security devices Lock down workstations and servers, update/patch regularly Locate WAP or wireless router outside the firewall if connected to a wired network If you have a wired network, locate your WAP or wireless router outside the firewall. If intruders penetrate your Wi-Fi network, they will not be able to access your wired network. (c) ITT Educational Services, Inc.

Create Gap-Free WLAN Security 9/22/2018 Create Gap-Free WLAN Security Strategically position WAPs Disable SSID broadcasting Enable all security features on WLAN devices Authentication Encryption (c) ITT Educational Services, Inc.

EXPLORE: ROLES

WLAN Security Roles Authentication Access Control Encryption 9/22/2018 Authentication and Access Control Authentication should allow both the originating station of transmitted data and the receiving station to verify each other. WAPs should use authentication and access control to grant access rights to requesting stations. Encryption and Data Privacy Encryption is a method that provides data integrity and privacy. Use Wi-Fi Protected Access 2 (WPA2), also known as IEEE 802.11i, as the security protocol for encrypted communications with Extensible Authentication Protocol (EAP). (c) ITT Educational Services, Inc.

EXPLORE: CONTEXTS

WiMAX Specified in IEEE 802.16 9/22/2018 WiMAX Specified in IEEE 802.16 Like 802.11n but wider range and better Quality of Service (QoS) Transmits up to 70 Mbps Access up to 30 miles (fixed stations), 3 to 10 miles (mobile stations) Line of sight not needed Ideal for metropolitan area networks Defines both the MAC and PHY layers and allows multiple PHY-layer specifications (c) ITT Educational Services, Inc.

WiMAX (Worldwide Interoperability for Microwave Access) Is a wireless industry coalition dedicated to the advancement of IEEE 802.16 standards for broadband wireless access (BWA) networks.

WiMAX Internet Fixed backhaul 9/22/2018 Defines both the MAC and PHY layers and allows multiple PHY-layer specifications Internet Fixed backhaul (c) ITT Educational Services, Inc.

WiMAX as Backbone for WAPs 9/22/2018 WiMAX as Backbone for WAPs Wireless Router Wireless Router Wireless Router Internet (c) ITT Educational Services, Inc.

Summary In this presentation, the following were covered: IEEE 802.11 a/b/g/h/i/n standards and specifications SSID broadcasting versus stealth mode WLAN design considerations and processes WLAN security considerations WLAN and WiMAX backbones

Assignment 5.3 A WLAN Solution Assignments Discussion 5.1 Advantages and Disadvantages of Wired and Wireless Networks Assignment 5.3 A WLAN Solution