IEEE and Networking Standards

The Institute of Electrical and Electronic Engineers (IEEE) developed a series of networking standards to ensure that networking technologies developed by respective manufacturers are compatible. This means that the cabling, networking devices, and protocols are all interchangeable when designed under the banner of a specific IEEE standard. Table 1.6 summarizes the IEEE 802 networking standards.

Table 1.6. IEEE 802 Networking Standards

Specification	Name
802.1	Internetworking
802.2	The LLC (Logical Link Control) sublayer
802.3	CSMA/CD (Carrier Sense Multiple Access with Collision Detection) for Ethernet networks
802.4	A token passing bus
802.5	Token Ring networks
802.6	Metropolitan Area Network (MAN)
802.7	Broadband Technical Advisory Group
802.8	Fiber-Optic Technical Advisory Group
802.9	Integrated Voice and Data Networks
802.10	Standards for Interoperable LAN/MAN Security (SILS) (Network Security)
802.11	Wireless networks
802.12	100Mbps technologies, including 100BASEVG-AnyLAN

Only a few of the standards listed in Table 1.6 are tested on the CompTIA exam. The standards that are specifically included in the CompTIA objectives are 802.2, 802.3, 802.5, and 802.11. Each of these IEEE specifications outlines specific characteristics for LAN networking, including the speed, topology, cabling, and access method. The following sections outline the key features of these IEEE specifications and the specific characteristics of each.

802.2 IEEE Standard

The 802.2 standard, referred to as the Logical Link Control (LLC), manages data flow control and error control for the other IEEE LAN standards. Data flow control regulates how much data can be transmitted in a certain amount of time. Error control refers to the recognition and notification of damaged signals. The LLC layer is discussed more in Chapter 4, "OSI Model and Network Protocols."

802.3 IEEE Standard

The IEEE 802.3 standard defines the characteristics for Ethernet networks. Ethernet networking is by far the most widely implemented form of local area networking. Several Ethernet LAN characteristics are identified in the 802.3 standard.

Since the development of the original 802.3 standards, there have also been several additions that have been assigned new designators. These standards are often referred to as the 802.3x standards. Some of the newer standards include 802.3u for Fast Ethernet, 802.3z for Gigabit Ethernet, and 802.3ae for 10-Gigabit Ethernet. The features for 802.3 are listed here:

• Speed The original IEEE 802.3 standard specified a network transfer rate of 10Mbps. There have been modifications to the standard, the result being Fast Ethernet (802.3u), which can transmit network data up to 100Mbps and higher, as well as Gigabit Ethernet (802.3z), which can transmit at speeds up to 1000Mbps. 802.3ae is a very fast 803.3 standard. Known as 10-Gigabit Ethernet, it offers speeds 10 times that of Gigabit Ethernet.

• Topology The original Ethernet networks used a bus or star topology because the original 802.3 standard included specifications for both twisted pair and coaxial cabling. The IEEE 802.3u and 802.3z specify twisted pair cabling and use a star topology. Remember that even when Ethernet uses a physical star topology, it uses a logical bus topology.

• Media The media refers to the physical cabling used to transmit the signal around the network. The original 802.3 specifications identified coaxial and twisted pair cabling to be used. The more modern standards specify twisted pair and fiber-optic cable. 802.3ae currently only supports fiber media.

• Access method The access method refers to the way that the network media is accessed. Ethernet networks use a system called Carrier Sense Multiple Access with Collision Detection (CSMA/CD). CSMA/CD works by monitoring the computers that are sending data on the network. If two computers transmit data at the same time, a data collision will occur. To prevent collisions, the systems sending the data will be required to wait a period of time and then retransmit the data to avoid the collision. 10-Gigbit Ethernet only operates in full-duplex mode and, as such, does not need to use the traditional Ethernet CSMA/CD access method.

One of the shortcomings of CSMA/CD is that as more systems are added to the network, the likelihood of collisions increases and the network becomes slower.

802.5 IEEE Standard

The IEEE 802.5 standard specifies the characteristics for Token Ring networks. Token Ring was introduced by IBM in the mid-1980s and quickly became the network topology of choice until the rise in popularity of Ethernet. It is unlikely that you will encounter a ring network in your travels and even more unlikely that you will be implementing a ring network as a new installation. For what it's worth, Token Ring is a solid network system, but Ethernet has all but eliminated it.

The following is a list of the specific characteristics specified in the 802.5 standard:

• Speed The 802.5 Token Ring specifies network speeds of 4 and 16Mbps.

• Topology Token Ring networks use a logical ring topology and most often a physical star. The logical ring is often created in the multistation access unit (MSAU).

• Media Token Ring networks use unshielded twisted pair cabling or shielded twisted pair. More information on the specific characteristics of twisted pair cabling is covered in Chapter 2, "Cabling and Connectors."

• Access method 802.5 specifies an access method known as token passing. On a Token Ring network, only one computer at a time can transmit data. When a computer has data to send, it must use a special type of packet known as a token. The token travels around the network looking for computers with data to send. The computer's data is passed along with the token until it gets to the destination computerat which point, the data is removed from the token and the empty token placed back on the ring.

All network cards on a Token Ring network must operate at the same speed.