12205_wlan

https://learningnetwork.cisco.com/community/connections/china Copyright @ 2010 Cisco Systems Inc. All rights reserved. This doc is for reference only. Please refer to the exam authority for details. If you want to repost this document, please properly reference the author and the source website https://learningnetwork.cisco.com/community/connections/china CCNA Study Group on Wireless LAN Authored by Mark Ng and Patrick Ng July 2010 Wireless LAN basics Wireless LAN refers to the networks where connectivity is provided not through physical cabling, but via radio waves. The most prominent and common standard is the IEEE 802.11 standard. The ITU, Wi-Fi alliance as we as the Federal Communications and Commission (FCC) also provide guidance to the building of standards. As of today, the available 802.11 standards include 802.11, 802.11b, 802.11g and 802.11n which prescribe different channels and speed supported. A wireless LAN device can operate in one of two modes: Ad hoc or Infrastructure mode. In Ad hoc mode, wireless LAN devices, usually PCs or handheld devices, communicate with each other directly. For example, a user my sync his/her mobile phone address book with his/her laptop by connecting the two devices in Ad hoc mode. In infrastructure mode, one or more special devices called an Access Point (AP) is involved. The AP, connected to the rest of the physical network, acted as an access devices where all the wireless LAN devices connect to. https://learningnetwork.cisco.com/community/connections/china Copyright @ 2010 Cisco Systems Inc. All rights reserved. This doc is for reference only. Please refer to the exam authority for details. If you want to repost this document, please properly reference the author and the source website https://learningnetwork.cisco.com/community/connections/china Wireless LAN advantages and disadvantages The biggest advantage of wireless LAN is that it is easy provide network access to devices and users, beca cables or installation of wall jacks users actually access the network. On the other hand, because of the open nature of wireless LAN, several challenges are presented. The first and f administrator needs to make sure that only authorized users have access to the network. Wireless LAN security When configuring wireless LAN de to several points: SSID SSID, or Service Set Identifier, is a string that identifies a particular wireless LAN device. By default, most APs broadcast their SSID so that users can find them. However, it is a good idea for an administrator to disable the broadcasting of SSID https://learningnetwork.cisco.com/community/connections/china Copyright @ 2010 Cisco Systems Inc. All rights reserved. This doc is for reference only. Please refer to the exam authority for details. If you want to repost this document, please properly reference the author and the source website ps://learningnetwork.cisco.com/community/connections/china Wireless LAN advantages and disadvantages ireless LAN is that it is easy for an administrato devices and users, because no running of physical or installation of wall jacks is needed, and it does not dictate where the users actually access the network. On the other hand, because of the open nature of wireless LAN, several The first and foremost of which is security administrator needs to make sure that only authorized users have access to the When configuring wireless LAN devices, an administrator needs to pay attention Service Set Identifier, is a string that identifies a particular wireless LAN device. By default, most APs broadcast their SSID so that users can find them. However, it is a good idea for an administrator to disable the broadcasting of SSID https://learningnetwork.cisco.com/community/connections/china This doc is for reference only. Please refer to the exam authority for details. If you want to repost this document, please properly reference the author and the source website for an administrator to use no running of physical is needed, and it does not dictate where the On the other hand, because of the open nature of wireless LAN, several oremost of which is security – the administrator needs to make sure that only authorized users have access to the pay attention Service Set Identifier, is a string that identifies a particular wireless LAN device. By default, most APs broadcast their SSID so that users can find them. However, it is a good idea for an administrator to disable the broadcasting of SSID https://learningnetwork.cisco.com/community/connections/china Copyright @ 2010 Cisco Systems Inc. All rights reserved. This doc is for reference only. Please refer to the exam authority for details. If you want to repost this document, please properly reference the author and the source website https://learningnetwork.cisco.com/community/connections/china and advise their authorized users of the SSID through other means. This way, it becomes more difficult for unauthorized users to connect to the AP. MAC filtering Most AP devices allow the administrator to configure MAC filtering. The administrator can configure a list of MAC addresses of wireless access devices such as wireless network interface cards, wireless USB dongles, etc so that only laptops or PCs with those devices can access the network through those APs. This is because it is relatively difficult for an unauthorized user to guess and fake the secret list of MAC addresses. Encryption Since wireless connectivity is provided through radio waves, it is possible for unauthorized users to sniff the network data by listening and deciphering the radio wave traffic. To protect the privacy of the wireless communication, an administrator needs to make sure the wireless traffic are encrypted. There are several encryption standards for wireless LAN available today: Wired Equivalent Privacy (WEP) In WEP, a static 64 bit or 128 bit key is preconfigured on both the AP and the accessing wireless devices. WEP is relatively insecure and difficult to scale because the encryption employed is weak and the key needs to be manually configured on all the accessing devices. WiFi Protected Access (WAP) The WPA-1 standard improves upon the security of WEP by employing TKIP (Temporal Key Integrity Protocol) encryption standard. At a later point, the WPA-2 comes along and replaced TKIP with the even more secure AES (Advanced Encryption Standard). It is important to note that not all wireless devices support WAP standard. In particular, devices manufactured before WAP standards were produced may not be upgradable to use the new standard.