Bài giảng Mạng máy tính căn bản: Chương 7 - Phan Vĩnh Thuần

Bài giảng Mạng máy tính căn bản - Chương 7: Các công nghệ Ethernet (Ethernet technologies) nhằm giúp người học mô tả sự khác biệt và tương đồng trong 10BASE5, 10Base2, và 10BASE-T Ethernet, xác định mã hóa Manchester, liệt kê các yếu tố ảnh hưởng Ethernet,...
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Bài giảng Mạng máy tính căn bản: Chương 7 - Phan Vĩnh ThuầnCHƯƠNG 7 CÁC CÔNG NGHỆ ETHERNET ETHERNET TECHNOLOGIESPhan Vĩnh Thuần Computer Network 1Overview• Ethernet has been the most successful LAN technology largely because of its simplicity of implementation compared to other technologies. Ethernet has also been successful because it has been a flexible technology that has evolved to meet changing needs and media capabilities. This module introduces the specifics of the most important varieties of Ethernet. The goal is not to convey all the facts about each type of Ethernet, but rather to develop a sense of what is common to all forms of Ethernet.Phan Vĩnh Thuần Computer Network 2• Changes in Ethernet have resulted in major improvements over the 10-Mbps Ethernet of the early 1980s. The 10-Mbps Ethernet standard remained virtually unchanged until 1995 when IEEE announced a standard for a 100 Mbps Fast Ethernet. In recent years, an even more rapid growth in media speed has moved the transition from Fast Ethernet to Gigabit Ethernet. The standards for Gigabit Ethernet emerged in only three years. An even faster Ethernet version, 10 Gigabit Ethernet, is now widely available and still faster versions are being developed.Phan Vĩnh Thuần Computer Network 3• In these faster versions of Ethernet, MAC addressing, CSMA/CD, and the frame format have not been changed from earlier versions of Ethernet. However, other aspects of the MAC sublayer, physical layer, and medium have changed. Copper- based network interface card (NICs) capable of 10/100/1000 operation are now common. Gigabit switch and router ports are becoming the standard for wiring closets. Optical fiber to support Gigabit Ethernet is considered a standard for backbone cabling in most new installations.Phan Vĩnh Thuần Computer Network 4• Students completing this module should be able to: – Describe the differences and similarities among 10BASE5, 10BASE2, and 10BASE-T Ethernet. – Define Manchester encoding. – List the factors affecting Ethernet timing limits. – List 10BASE-T wiring parameters. – Describe the key characteristics and varieties of 100-Mbps EthernetPhan Vĩnh Thuần Computer Network 5 – Describe the evolution of Ethernet. – Explain the MAC methods, frame formats, and transmission process of Gigabit Ethernet. – Describe the uses of specific media and encoding with Gigabit Ethernet. – Identify the pinouts and wiring typical to the various implementations of Gigabit Ethernet. – Describe the similarities and differences between Gigabit and 10 Gigabit Ethernet. – Describe the basic architectural considerations of Gigabit and 10 Gigabit Ethernet.Phan Vĩnh Thuần Computer Network 67.1.10-Mbps and 100-Mbps Ethernet7.1.1. 10Mbps Ethernet• 10BASE5, 10BASE2, and 10BASE-T Ethernet are considered Legacy Ethernet. The four common features of Legacy Ethernet are timing parameters, frame format, transmission process, and a basic design rulePhan Vĩnh Thuần Computer Network 7Phan Vĩnh Thuần Computer Network 8• 10BASE5, 10BASE2, and 10BASE-T all share the same timing parameters, as shown in the figure (1 bit time at 10 Mbps = 100 nsec = 0.1 µsec = 1 ten-millionth of a second.)Phan Vĩnh Thuần Computer Network 9• 10BASE5, 10BASE2, and 10BASE-T also have a common frame format.Phan Vĩnh Thuần Computer Network 10Phan Vĩnh Thuần Computer Network 11• The Legacy Ethernet transmission process is identical until the lower part of the OSI physical layer. The Layer 2 frame data is converted from hex to binary. As the frame passes from the MAC sublayer to the physical layer, further processes occur prior to the bits being placed from the physical layer onto the medium. One important process is the signal quality error (SQE) signal. SQE is always used in half-duplex. SQE can be used in full-duplex operation but is not required.Phan Vĩnh Thuần Computer Network 12• SQE is active: – Within 4 to 8 microseconds following a normal transmission to indicate that the outbound frame was successfully transmitted – Whenever there is a collision on the medium – Whenever there is an improper signal on the medium. Improper signals might include jabber, or reflections that result from a cable short. – Whenever a transmission has been interruptedPhan Vĩnh Thuần Computer Network 13• All 10 Mbps forms of Ethernet take octets received from the MAC sublayer and perform a process called line encoding. Line encoding describes how the bits are actually signaled on the wire. The simplest encodings have undesirable timing and electrical characteristics. So line codes have been designed to have desirable transmission prop ...