IEEE stands for Institute of Electrical and Electronics Engineers. In the second month of 1980 subcommittees of the institute met to define the standards of LANs and MANs, thus the name, 802. There are currently 12 major standards. They are:
802.1 LAN/MAN Management (and Media Access Control Bridges): This standard covers management of LANs/WANs and MAC bridges. The spanning tree algorithm (which will be discussed in greater detail later) is also covered here. This algorithm prevents bridge loops in a multibridged network.
802.2 Logical Link Control: The operation of the logical link control (LLC) sublayer of the data link layer is discussed in this standard. The 802.2 standard is used by the 802.3 standard.
802.3 CSMA/CD (Carrier Sense Multiple Access/Collision Detection): This is the most widely implemented of all the 802 standards due to its simplicity and low cost. It specifies a network that uses a bus topology, baseband signaling, and a CSMA/CD network access method. It is commonly referred to as Ethernet.
802.4 Token Bus: This standard is mostly used for factory automation and is seldom used for computer networking. It specifies a physical and logical bus topology that uses fiber optic or co-axial cable and a token passing media access method.
802.5 Token Ring: Most of the time standards are written and then products are developed to conform to the standard. In this instance, in 1984 IBM developed token ring technology with the standard being released afterward. As in Ethernet, Token Ring utilizes several, different cable types. Most often it uses twisted pair cabling, either shielded or unshielded. Token Ring uses:
Token Ring networks are still in wide usage because IBM made sure that it was able to communicate well with IBM mainframes and it "degrades with grace". An Ethernet network can fail if it becomes flooded with too much traffic. Token Ring, on the other hand, will slow down as the single token (that can only travel in one direction) becomes overwhelmed; "degrades with grace". Other differences between Token Ring and other networking schemes include different names for what are commonly referred to as hubs and the classification system used for cabling. IBM call their hub-like device a MAU (Multi-Station Access Unit) and they use types of cabling rather then the more common CATs (categories). Finally, Token Ring uses a regeneration process in which data signals are read, amplified, and repeated by every device on the network. This reduces data degradation.
802.6 Distributed Queue Dual Bus Metropolitan Area Network (DQDBMAN): As previously stated MANs generally cover a city-sized area and can support many-to-many connections. This standard recommends the use of Distributed Queue Dual Bus (DQDB) technologies for MANs.
802.7 Broadband Local Area Networking: When one cable carries multiple signals it is utilizing broadband technology. The alternative is to use the entire cable for one signal. This is the technology utilized by Ethernet.
802.8 Fiber Optic LANs and Mans: This standard covers the use of fiber-optics on the network types defined by 802.3-802.6.
802.9 Integrated Services (IS)/LAN Interface: This standard lays out how Integrated Switched Digital Networking (ISDN) behaves. With the rise of cable modems and Asymmetrical Digital Subscriber Lines (ADSL) ISDN usage is on the decline.
802.10 LAN/MAN Security: This standard provides a secure pathway for data across a shared path. This standard applies to situations in which the public Internet is used as a backbone for a private interconnection between locations. This form of interconnecting is referred to as Virtual Private Networking (VPN).
802.11 Wireless LAN: This standard covers the usage of wireless technologies and is, currently, the most dynamic of all the standards, changing to keep pace with changes and improvements in wireless technology.
802.12 Demand Priority Access Method: First developed by Hewlett-Packard this standard combines the concepts of Ethernet and ATM (Asynchronous Transfer Mode). It uses "intelligent" hubs that allocate more bandwidth to frames that have been assigned a higher priority by the sending computer. This is extremely valuable for real-time audio and video transmissions. 802.12 is also known as 100VG (Voice Grade), 100VG-AnyLAN, 100BaseVG, and AnyLAN.
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