Network+ 2008 Tutorial

Wireless Communication Standards

Wireless is becoming standard beyond the homes and into companies. Secure access and new features makes wireless the choice of networking for many organizations.

As wireless has grown up, so have its complexities. Sure, setting up an 802.11n network at home is quite simple, but setting up secure access wireless networking in a corporate environment is much more complex.

For the CompTIA Network+ 2005/2008 exams, you should be aware of the different standards for wireless communications and security standards for maintaining security in your network.

There are four primary wireless communication standards: 802.11a, 802.11b, 802.11g, and 802.11n.

802.11a

The 802.11a wireless networking standard operates in the 5Ghz band at a maximum transfer speed of 54 Mbit/s. The 5Ghz band is not as crowded as the 2.4Ghz band, so 802.11a has its advantages over 802.11b and 802.11g. The effective range of 802.11a is less than 802.11b and 802.11g as it is more easily absorbed by walls and objects. However, the increased number of usable channels and near absence of interference (unlike 802.11b and 802.11g which suffer from interference from microwaves, baby monitors, cordless phones, and more) gives 802.11a a significant bandwidth advantage over 802.11b.

802.11b

The 802.11b wireless networking standard operates in the 2.4Ghz band with a maximum data transfer rate of 11 Mbit/s. 802.11b uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) which has an overhead limiting practical TCP bandwidth to 5.9 Mbit/s.

The 2.4Ghz band also has a tremendous amount of interference from devices such as microwave ovens, cordless phone, baby monitors, and Bluetooth devices. This interference can cause the data transfer rate to be reduced even further.

802.11g

802.11g is the third commercial iteration of the 802.11 wireless networking standard with a maximum data throughput of 54 Mbps running in the 2.4Ghz band – the same as 802.11b. 802.11g is backwards compatible with 802.11b, allowing those devices to operate in the same network as 802.11g nodes. However, mixing 802.11b and 802.11g devices in a network will drop the overall speed of the network closers to 802.11b speeds.

802.11g suffers from the same interference issues that 802.11b does.

802.11n

The 802.11n wireless networking standard is currently in draft form and is not a finalized, approved wireless networking standard. However, many manufacturers have released pre-N, MIMO-based, or draft-N devices in anticipation of approval sometime in 2009.

802.11n networks are anticipated to have a max throughout of around 248Mbits/s, while retaining backward compatibility with 802.11a, 802.11b, and 802.11g. It achieves these speeds by using multiple-input multiple-output (MIMO) technology and bringing 40Mhz operation to the physical layer. MIMO uses multiple antennas to transmit and receive data.

Wireless Security

Unsecured wireless networks cause the potential for hackers to not only gain access to the network, but to eavesdrop on the data packets travelling on the network. This presents a significant security risk which is causing a slow adoption of wireless networks in corporate America.

Wired Equivalent Privacy

Originally, wireless networking vendors supported Wired Equivalent P
rivacy (WEP)
to secure wireless networks, but security analysts determined several security holes leaves WEP open to cracking in just a few minutes. Therefore, the IEEE created two new standards for security on wireless networks: WPA and WPA2. Today, though WEP is still in wide use, its use as a security measure is not recommended.

Wi-Fi Protected Access

Wi-Fi Protect Access (WPA) was created as a method of securing wireless network communications without the design flaws of WEP. WPA is a subset of the full standard, referred to as WPA2.

In practice, there are two standards for WPA: personal and enterprise. Personal WPA uses a pre-shared key (PSK), a passphrase used by every client on the network. The enterprise version of WPA uses an IEEE 802.1X authentication server which distributes a key to each user.

Wi-Fi Protect Access 2 (WPA2)

The full 802.11i standard sets the requirements for WPA2 with an AES-based algorithm called CCMP. This version is considered fully secure and has a little more overhead than WPA.

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