Bài giảng Lecture 5 - WLAN Infrastruc
Wireless LAN Infrastructure Devices (1 September, 2006) February 2005 Copyright 2005 All Rights Reserved Objectives Upon completion of this chapter you will be able to: q Configure, install, and manage wireless infrastructure devices q Configure, install, and manage wireless client devices q Configure, install, and manage the different types of wireless gateways February 2005 Copyright 2005 All Rights Reserved Access Point Operating Mode February 2005 Copyright 2005 All Rights Reserved Access Point q The Access Point (AP) provides mobile station access to the wired network q The Access Point (s) and its configuration can determine the WLAN topology Independent Basic Service Set (IBSS) also called Ad-Hoc networks Infrastructure Basic Service Set (BSS) Extended Service Set (ESS) q An Access Point can be configured in three modes Root Mode Repeater Mode Bridge Mode February 2005 Copyright 2005 All Rights Reserved Access Point Contd This Access Point is operating in the Root Mode within a Basic Service Set (BSS) Topology (single AP connected to the LAN) February 2005 Copyright 2005 All Rights Reserved Root Mode q The Root Mode is the default configuration for an AP q The Access Point (AP) is in Root Mode when it is: Connected to the Wired Lan (BSS and EBSS) or Operating in AD-Hoc mode q Two or more APs connected to the same Wired Lan can communicate with one another thus facilitating MS roaming February 2005 Copyright 2005 All Rights Reserved Bridge Mode q An AP configured for the bridge mode connects two wired Local Area Networks It creates a point-to-point connection between Access Points It is normally used with semi or highly directional antennas An AP bridge only associates with another AP Bridge The remote location may require two APs One for the bridge and one for wireless access, however, Some APs can be configured to operate as both a Bridge and AP February 2005 Copyright 2005 All Rights Reserved Repeater Mode q An AP operating in Repeater mode connects remote mobile stations to a "root" access point The repeater AP acts as a normal AP to the remote mobile stations while simultaneously acting as client to the "root" Access point Both the "root" and the "repeater" can have mobile station clients The BSS area around both AP will overlap a minimum of 50% thereby reducing the throughput of the mobile units The "repeater" AP must have an omnidirectional antenna February 2005 Copyright 2005 All Rights Reserved Access Point Options February 2005 Copyright 2005 All Rights Reserved Access Point Options q Fixed or Detachable Antennas Detachable antennas provide greater flexibility Highly directional antennas may be required The AP and antenna must be certified as a system (FCC Part 15 Rules) Diversity antennas may be required, that is, two antennas to compensate for multipath reception q Filtering – Employed to screen out intruders MAC filter – Filters out intruders based upon the NIC card address Protocol Filter - Filters out intruders based upon a TCP/IP protocol, eg., UDP, TCP, ICMP, etc February 2005 Copyright 2005 All Rights Reserved 10 Access Point Options contd q Mounting options The site survey will determine the location of the AP Assure power and wire connectivity are available at the mounting site Use vendor mounting kits if possible The AP mounting location should be inconspicuous The APs status lights should be visible The mounting locations should provide convenient access to the AP Employ NEMA compliant enclosures when mounting the AP outside (NEMA Standards publication 250 NEMA Type 4) February 2005 Copyright 2005 All Rights Reserved 16 Access Point Mounts February 2005 Copyright 2005 All Rights Reserved 17 Wireless Bridge February 2005 Copyright 2005 All Rights Reserved 18 Wireless Bridge q A wireless bridge provides a point-to-point link between LANS Most APs can be configured as a bridge while most bridges can be configured as an AP The difference between the two is generally one of intent February 2005 Copyright 2005 All Rights Reserved 19 Wireless Bridge Contd q Bridge Modes One bridge must be a root while the other bridge must be non-root q Bridge Alignment can be accomplished by: A Software Utility that reads signal strength Through LEDs on Bridge or Through a Voltmeter Root = Off February 2005 Root = On Copyright 2005 All Rights Reserved 20 Wireless Bridge Contd q Bridge Options Alignment Enterprise grade bridges generally include some method for aligning bridges whereas a consumer grade does not Optimize the alignment then rotate the antenna around it polarization axis to maximize the signal strength Long range alignment tools should include such things as: Path calculation (http://www.connect802.com/antenna_c_main.php) GPS device and GPS enabled topographical maps http://www.cisco.com/warp/public/102/wlan/faq-hardware-us-calc.html February 2005 Copyright 2005 All Rights Reserved 21 Wireless Workgroup Bridges q A Wireless Workgroup Bridge (WGB) connects multiple wired clients to an Access Point (AP) The WGB acts as a client to the AP The WGB forwards and filters the packets from the wired clients Consumer grade WGB can handle between 8-16 clients An Enterprise grade WGB can handle up to 255 clients February 2005 Copyright 2005 All Rights Reserved 22 Wireless Router February 2005 Copyright 2005 All Rights Reserved 23 Wireless Router q A wireless router is an Access Pont that routes packets between the wireless and the wired LAN whereas a regular AP bridges the frames The wireless interface has its own IP and subnet and The wired interface has its on IP and subnet Mobile stations roaming between subnets may break an application q One advantage of a Wireless Router is that it may be easier to implement a VPN point in the router than an AP A normal AP may forward the encrypted VPN packet to an endpoint on the Wired network for decryption and forwarding February 2005 Copyright 2005 All Rights Reserved 24 Outdoor Wireless Router Enterprise Wireless Router MIMO Wireless Router February 2005 SOHO Wireless Router Copyright 2005 All Rights Reserved 25 Wireless Client Devices February 2005 Copyright 2005 All Rights Reserved 26 Wireless Client Devices q Wireless LAN clients are radio Network interface cards that are recognized by the Access Point q The clients include but are not limited to: PCMCIA cards, Compact Flash and Secure Digital Cards PCI, mini-PCI cards and USB devices PCMCIA-to-PCI adapters and Serial/Ethernet converters q Installation includes WLAN card drivers PC Wireless Adapter Utilities Survey tools AP Monitoring tools Link testing, etc February 2005 MU PCMCIA Card Copyright 2005 All Rights Reserved 27 PCMCIA Cards and Converters PCMCIA Card PCI Adapter Wireless Compact Flash February 2005 Copyright 2005 All Rights Reserved 28 Wireless Adapters USB Wireless Adapter Ethernet and Serial Converter USB Wireless Adapter February 2005 Copyright 2005 All Rights Reserved 29 End of Presentation February 2005 Copyright 2005 All Rights Reserved 30 ... publication 250 NEMA Type 4) February 20 05 Copyright 20 05 All Rights Reserved 16 Access Point Mounts February 20 05 Copyright 20 05 All Rights Reserved 17 Wireless Bridge February 20 05 Copyright 20 05 All... handle between 8-1 6 clients An Enterprise grade WGB can handle up to 255 clients February 20 05 Copyright 20 05 All Rights Reserved 22 Wireless Router February 20 05 Copyright 20 05 All Rights Reserved... GPS enabled topographical maps http://www.cisco.com/warp/public/102 /wlan/ faq-hardware-us-calc.html February 20 05 Copyright 20 05 All Rights Reserved 21 Wireless Workgroup Bridges q A Wireless Workgroup