Cisco is a major player in the wireless networking market, so it was expected that an understanding of wireless networking would be a feature of the CCNA exam. The previous update removed it completely, probably due to the new CCNA Wireless exam that has been created.
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Based on the interviews of Cisco customers, the consensus is that wireless is a subject that even CCNA engineers should understand. This makes sense because many corporate networks feature wireless networking to some degree, and the field is rapidly developing. For this reason, wireless networking is back in the exam, albeit in a stripped-down version. You will not be expected to have an in-depth understanding of protocols, security, and site surveys, but you will need to understand the impact of wireless devices as well as have a basic understanding of installation steps.
There are so many advantages to wireless networking that it is now integrated into almost every home and corporate network. Wireless removes the cost and the huge inconvenience of installing wiring; it also removes all the associated cable-related issues, including major network outages and downtime.
The IBSS is rarely used in modern networks; it uses the ad-hoc mode whereas the wireless network uses Wi-Fi capability without the use of any access points. An example of an ad-hoc network would be two workstations establishing a direct wireless connection without the use of an intermediary access point (the equivalent of directly connecting two workstations through an Ethernet crossover cable instead of using a switch). The BSS approach, also called wireless infrastructure mode, is much more common. It involves the use of access points that act as traffic hubs, as described earlier.
The ESS (also operating in infrastructure mode) involves the use of multiple access points that are servicing the same SSID. This allows individuals to cover a larger distance with their wireless devices in a transparent and seamless manner. These users can move from AP to AP, keeping the same SSIDs.
It is worth making a note of the various standards available for wireless networks. Bear in mind, though, as already stated, this is a rapidly developing technology, so do some further research before taking the exam.
802.11 wireless standards are all managed by the international IEEE LAN/MAN standards committee. There have been many updates to 802.11 over time, with one of the most recent larger updates made in 2007.
Most wireless products are branded with the Wi-Fi trademark logo (illustrated in Figure 8.2 below), which means that the device has gone through testing that verifies that it will work and interoperate properly with other wireless devices.
Access points can function as repeaters (see Figure 8.5 above), accepting a weak RF signal, strengthening (amplifying) it, and resending it. This operation is used to extend the range of wireless networks.
The WLAN mesh topology (see Figure 8.6 above) is the most sophisticated and most used wireless topology. When used in this type of topology, the AP can function as a repeater or as a bridge, as needed, based on RFs. This technology allows designers to use wireless technologies to cover large geographical areas and ensures features such as:
One of the advantages of using the Cisco unified wireless solution is that as a centralized control architecture, it offers reduced TCO, improved visibility, dynamic RF management, enhanced WLAN security, enterprise mobility, and improved productivity and collaboration.
The CCNA Wireless and Cisco Design exams cover WLAN design considerations in great detail. When designing the wireless network, controller redundancy should be carefully analyzed. Radio channels require an RF site survey and management by certified wireless professionals. Note also the power supply locations and amount of output, the number of WLCs required, and the placement of WLCs (security/roaming).
Considering the scenarios mentioned above, end-users will most likely move from one location to another. The solution to this issue is the roaming and mobility features that give users the ability to access the network from different locations. Roaming occurs when wireless clients change their association from one LWAP to another without losing connectivity. Network designers should carefully scale the wireless network to allow for the client roaming process. Wireless roaming can be divided into two categories:
LWAPP allows the move of intelligence away from the access point and shares it with WLCs. WLCs handle wireless policies, control messaging setup, authentication, and wireless operations. WLCs can also be considered the bridge between wireless networks and wired networks. WLC devices can manage multiple access points, providing configuration information as well as firmware updates on an ad-hoc basis.
Layer 3 LWAPP tunnels are used between access points and wireless LAN controllers to transmit control messages. It uses UDP port 12223 for control and UDP port 12222 for data messages. Cisco LWAPs can operate in six different modes:
Bridge mode typically operates on outdoor access points that function in a mesh topology. This is a cost-effective high-bandwidth wireless bridging connectivity mechanism, and it includes Point-to-Point or Point-to-Multipoint bridging.
CAPWAP, which is based on LWAPP, is a standard, interoperable protocol that enables a controller to manage a collection of wireless APs. LAPs can discover and join a CAPWAP controller. The one exception is for Layer 2 deployments, which are not supported by CAPWAP. Additionally, CAPWAP and LWAPP controllers may be deployed in the same network. The CAPWAP-enabled software allows APs to join a controller that runs either CAPWAP or LWAPP.
The wireless LAN is basically the SSID network name. Every wireless LAN is assigned to an interface in the WLC, and each wireless LAN is configured with policies for RF, QoS, and other wireless LAN attributes.
You should also think about the positioning of the inside walls in each particular area of the building. You should try to avoid having metal and concrete walls between access points and the users, as these materials often block or attenuate the wireless signal. You should also analyze and decide on the type of antennas you need to use in your wireless environment. In addition, make sure that you use an antenna that is strong enough and has a high enough gain to be able to get through the walls that may impede the signal from the AP from reaching the users.
Security is an essential aspect of wireless networks because such networks are a shared and open medium with no default protection, so everyone can access it. The solution to confidentiality issues is to encrypt the data that flows through a Wi-Fi environment so that only people who are authorized can transmit and receive data.
The recommended WLAN security protocol is WPA2, based on the 802.11i architecture. WPA2 can be integrated with the 802.1X architecture that can work on top of either an 802.3 (wired) or an 802.11 (wireless) environment. This allows individual users and devices to authenticate using the Extensible Authentication Protocol (EAP) and an authentication server (RADIUS or TACACS+). WPA2 and 802.11i also involve the Robust Security Network (RSN) concept that is used to keep track of the associations to the access points.
Another security design issue you have to deal with is unauthorized access. In wireless networks, there are no physical boundaries, so attackers can gain access from outside the physical security perimeter. They can introduce rogue access points or soft access points on laptops or handheld devices that can breach security policies. As wireless signals are not easily controlled or contained, this could create security issues for the network.
MAC address security can be used to allow only certain devices to associate with the access points, but this cannot prevent MAC address spoofing techniques. Another solution involves MAC address filtering, but this is not very scalable when dealing with a large number of wireless clients. The most efficient solution to this problem is using 802.1X port-based authentication, which will be described in a subsequent section.
Another important security aspect in WLAN networks involves controlling WLAN access to servers. Just as you would place DNS servers that are accessible from the Internet in a DMZ segment, you should apply the same strategy to RADIUS/TACACS+ and DHCP servers used in the wireless LAN solution. These servers should be placed into their own VLAN that has a strictly controlled network access policy. These servers should also be protected against Denial of Service (DoS) attacks using Intrusion Prevention System (IPS) solutions.
Because of the large amount of GUI screenshots required, we have moved the wireless labs onto the free support page. They are all in video format, and you can configure them using Packet Tracer, which is a free download from Cisco.
For any network administrator whose career involves a focus on wireless technologies -- or may some day, Certified Wireless Network Administrator is the perfect certification. The CWNA cert is provided by Certified Wireless Network Professionals, and after taking the CWNA-108 exam, you'll know your way around every technology, device and problem a wireless network could throw at you.
All of CWNP exams are vendor-neutral, which means you're not focusing on a particular brand or manufacturer, but on 802.11 technology. This is a huge plus for any administrator eager to learn about wireless technology generally rather than specific products.
For anyone who manages a wireless network, this wireless training can be used for CWNA-108 exam prep, onboarding new network administrators, individual or team training plans, or as a reference resource.
This Certified Wireless Network Administrator training is considered professional-level training, which means it was designed for network administrators with at least a year of experience with wireless network administration and experienced network administrators looking to validate their skills. 2ff7e9595c
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