Copyright Goodheart-Willcox Co., Inc. 66 Networking Fundamentals Logical Link Control. In this section, you will learn specifi cally about the 802.3 stan- dard, which describes Ethernet network specifi cations and specifi es the use of cop- per cabling. IEEE 802.3 Classifi cations Th e IEEE 802.3 standard comprises various Ethernet classifi cations. Th ese clas- sifi cations diff er by data rate, topology, and media type and are named with short descriptions, such as 10BaseT and 10Base2. Th e chart in Figure 2-19 lists common- ly encountered IEEE 802.3 classifi cations along with the maximum and minimum segment lengths in meters, data rate, cable type, and the topology of each. Th e 802.3 classifi cations are divided into four categories: 10 Mbps, Fast Ethernet, Gigabit Eth- ernet, and 10 Gigabit Ethernet. Th ere is also Jumbo Frame, which is an Ethernet frame with a payload greater than the standard maximum transmission unit (MTU) of 1500 bytes. Frames will be discussed in detail in Chapter 5. 2.1, 2.4 NET Goodheart-Willcox Publisher Note: 1000BaseCX is obsolete and is no longer recognized. Figure 2-19 IEEE 802.3 categories and classifications. Category Classifi cation Data Rate Maximum Segment Length Minimum Segment Length Cable Type Topology 10 Mbps 10Base2 10 Mbps 185 m 0.5 m RG-58 (thinnet) Bus 10Base5 10 Mbps 500 m 2.5 m RG-8 (thicknet) Bus 10BaseT 10 Mbps 100 m 0.6 m Category 3, 4, and 5 Star Fast Ethernet 100BaseT4 100 Mbps 100 m 0.6 m Category 3, 4, and 5 Star 100BaseTX 100 Mbps 100 m 0.6 m Category 5 Star Gigabit Ethernet 1000BaseCX 1000 Mbps 25 m 0.6 m Category 5 Star 1000BaseT 1000 Mbps 100 m 0.6 m Category 5e Star 10 Gigabit Ethernet 10GBaseT 10 Gbps 55 m 0.6 m Category 6 Star 10GBaseT 10 Gbps 100 m 0.6 m Category 6a Star To help you decode the cryptic names of the classifi cations and to remember the specifi cations for each, look at Figure 2-20. In the fi rst two examples, the 10 rep- resents the data rate, which is 10 Mbps. In the third example, the 100 represents 100 Mbps. Th e Base in these examples stands for Baseband, which means that the digital signal is transmitted at one frequency, and this frequency consumes the entire bandwidth of the cable. Th e last symbol in a cable classifi cation is usually a number or a letter. A num- ber indicates the approximate maximum segment length in hundreds of meters, and a letter indicates the media type. For example, in Figure 2-20A, the 2 represents the approximate maximum length of a segment in meters. A 10Base2 segment can there- fore have a maximum length of approximately 200 meters (2 × 100). Th e actual maxi- mum length, however, is 185 meters, but the 2 serves as an approximate. Th e 10Base5 classifi cation specifi es a maximum segment length of 500 meters (5 × 100). In this case, 500 meters is the actual maximum segment length.