What are 802.11 wireless networks (hereinafter referred to as WLANs in this post)? A wireless network, as the name suggests, is a network that uses radio waves to connect devices, such as laptops, desktops, and mobile phones to the Internet, your organizational network, and applications hosted on your network. Wireless networks, unlike wired networks, do not use physical transmission media, such as wires and LAN cables. WLAN implementation is done at the Physical and Data Link layers of the OSI model. Implementing a wireless network enables the organizations/business establishments to reduce the cost of laying the cables for a wired network while providing high-speed data transmission, which can be used by both stationary and mobile users. A common example of a wireless network is your mobile phone network, though it does not use 802.11. Implementing a wireless network provides the following advantages:
WLANs provide mobility to the Internet user. Using a WLAN, you can be connected to the Internet or your organization’s network while being on the move.
WLANs are compatible with IP networks.
WLANs provide high speed and secure data transmission.
WLANs provide ease of installation and use, and are scalable at a low cost.
WLANs evolved from legacy radio frequency data technologies. As WLANs evolved as a data transfer technology, the Institute of Electrical and Electronics Engineers (IEEE), an organization that promotes new technologies and creates standards and protocols that govern these new technologies, created the IEEE 802.11 – 1997 standard, the first standard for WLANs.
We will discuss the IEEE and other organizations that are involved in the implementation and standardization of a wireless network.
The IEEE is an organization of professionals, with its headquarters in New York City and operations center in New Jersey. Founded in 1963, the IEEE is today the world’s largest association of technical professionals, which includes computer scientists, information technology professionals, software engineers, and physicists. The IEEE is primarily involved in educational and technical advancement of electrical and electronic research, computer engineering, telecommunications, and similar disciplines. For more information about IEEE and how it came into existence, refer to the http://en.wikipedia.org/wiki/Institute_of_Electrical_and_Electronics_Engineers web page.
The IEEE formed the IEEE 802 LAN/MAN Standards Committee (LMSC) that develops and maintains networking standards and protocols for various network technologies, such as Ethernet, wireless networks (LAN, PAN, and WAN), media independent handover devices, and other such technologies. This LMSC committee has a working group for each of these networking technologies, some of which are given below:
802.1: Higher Layer LAN Protocols working group
802.3: Ethernet working group
802.11: Wireless LAN working group
802.15: Wireless Personal Area Network (PAN) working group
For more information all the working groups of the IEEE 802 LAN/MAN Standards Committee, refer to the http://www.ieee802.org/ web page.
The 802.11 Wireless LAN working group came into existence in 1991 to create standards for 1 MB/sec Radio Frequency (RF) based data network technology. This working group provided the first 802.11 standard in 1997, called the 802.11 Wireless LAN standard, which is implemented at the Physical Layer and the Data Link Layer of the OSI model. The 802.11 standard has now become the basis for all the development and updates in the field of WLAN data network technology.
Another organization that is involved in creating standards for Internet technologies is the Internet Engineering Task Force (IETF). The IETF works to standardize Internet technologies and protocols especially the Internet Protocol Suite (TCP/IP). Initially, IETF started as an activity supported by the United States federal government but from 1993, it started working under the Internet Society umbrella, an international membership-based non-profit organization, to develop networking standards. For more information about IETF, refer to the https://www.ietf.org/ and http://en.wikipedia.org/wiki/Internet_Engineering_Task_Force web pages.
IETF develops standards using the process called Request for Comments (RFCs). An RFC is a document that is authored by computer scientists and engineers in the form of a memorandum to describe methods, behaviors, innovations, or research results for the working of the Internet or Internet-related systems/technologies. Some of these RFCs are adopted and implemented as Internet standards. Since its invention by Steve Crocker in 1969, the RFC is now an official document for Internet communications and network protocols. Some of the IETF RFCs that have been adopted as standards, and implemented to build either a wireless or a wired LAN network are:
The following figure illustrates a typical RFC document.
RF wavelength calculations can be made quite simple with two basic formulas. One for feet and the other for meters. This blog post provides the formulas and an Excel
spreadsheet for calculating the wavelengths for each 20 MHz channel center frequency in the 2.4 GHz and 5 GHz bands.
The length of RF waves impacts antenna design decisions. Antennas should be designed so that they best receive in the frequencies intended. This means understanding the wavelength of the RF waves generated in a given frequency.
802.11 channels work on a center frequency. The image below shows the spreadsheet available here, which also shows the center frequencies for each 20 MHz channel in 2.4 GHz and 5 GHz.
he common formula for calculating wavelength in feet is:
wavelength = 984 / frequency in MHz
To calculate the wavelength in meters use:
wavelength = 300 / frequency in MHz
These formulas are shown, more scientifically, in the image above. Download the spreadsheet and take a look at the result for the different center frequencies using the drop down boxes provided in the Frequency column.
In this blog, we will talk about protocol analyzers, what they do, why they are important for a network engineer, and which is the best protocol analyzer available in the market today. These are lot of questions to be answered in a single blog, but I will try.
What are protocol analyzers?
They are always-have-it tools in the network administrator’s toolkit, and are used for network protocol analysis, and are also called packet sniffers. They are primarily used to capture data packets and protocol details from a communication channel and decode their various components. Also, if you, as a network administrator, needs to know why a network device is functioning the way it is, then you would need a protocol analyzer to capture the network traffic going in and out of that device to understand the protocols that are utilized.
With the help of a network protocol analyzer, you can perform a lot of network traffic analysis and network troubleshooting, which includes the following:
- Detect and identify malicious software available in the network
- Eavesdrop on network traffic to locate unauthorized access points or users
- Work in collaboration with the Intrusion Detection System (IDS) to identify unauthorized users
- Learn about the network in general
The following diagram illustrates how a typical network protocol analyzer works:
Unlike the common belief that network protocol analyzers were only useful for troubleshooting network problems, now days, protocol analyzers are used in day-to-day network management, and perform the following functions:
Monitor unexpected network traffic. As a primary function, protocol analyzers capture network traffic, and if any unusual traffic is detected, protocol analyzers can be put into use to capture and analyze this unexpected traffic for security or performance reasons.
Monitor unnecessary network traffic. As a good network management practice, any unused network protocols should be removed. For example, some older printers may try to communicate using Novell’s IPX protocol, though rare today. Therefore, the protocol analyzers can be used to filter specific type of network traffic so that you can monitor bandwidth usage and identify the non-used protocols.
Detect unauthorized users accessing the resources. A network management practice is to periodically check for the services provided by your servers. Some servers can be providing unauthorized services or unauthorized users might be accessing the servers, both of which are detrimental for your network. Protocol analyzers can be put to use here as well, and packets from the servers can be captured to identify which services are running on the server. After you have identified the services being run on the server, you can disable the services that are unauthorized or not required. This will help you to reduce unnecessary network traffic and prevent unauthorized users to access the servers on the network.
Detect viruses and control their spread within the network. Protocol analyzers can be used to detect virus in the transmission by allowing to build specific virus detection filters.
Resolve email problems, now did you even think of this!! Yes, protocol analyzers can be used to detect problem with your email server because email systems use standard port numbers, and protocol analyzers can be used to monitor both incoming and outgoing email traffic to detect any issue or cause of an email problem. Of course, this is just one example as any standard protocol can be captured and analyzed, assuming it is not encrypted.
Tagged with: CWNP, Wireless, Wi-Fi Certification, wifi certification, wireless certification, IT Professional, WLAN, WLAN Certification, CWTS, CWNA, CWAP, CWSP, CWDP, CWNE, Protocol Analyzers