复旦大学：《计算机网络 Computer Networking》课程教学资源（PPT课件讲稿）Ethernet LANs

Ethernet lans Chapter 4 Updated January 2009 XU Zhengchuan Fudan University

Ethernet LANs Chapter 4 Updated January 2009 XU Zhengchuan Fudan University

Orientation Chapters 2 and 3 Looked at Standards Chapter 2: Layered standards(data link to application) Chapter 3: Physical layer standards Chapters 4-7 Deal With Single Networks Chapter 4: Ethernet LANS Chapter 4a deals with obsolete Token-Ring Networks Chapter 5: Wireless LaNs Chapters 6 and 7: WaNs Flow is from laNs to wans 4-2

4-2 Orientation • Chapters 2 and 3 Looked at Standards – Chapter 2: Layered standards (data link to application) – Chapter 3: Physical layer standards • Chapters 4-7 Deal With Single Networks – Chapter 4: Ethernet LANs • Chapter 4a deals with obsolete Token-Ring Networks – Chapter 5: Wireless LANs – Chapters 6 and 7: WANs – Flow is from LANs to WANs

Figure 4-1: A Short History of Ethernet standards · Ethernet The dominant wired Lan technology today Only"competitor"is wireless LANs(which actually are supplementary) The EEE 802 Committee LAn standards development is done primarily by the Institute for Electrical and Electronics Engineers(IEEE) lEEE created the 802 LAN Man Standards committee for Lan standards(the 802 Committee 4-3

4-3 Figure 4-1: A Short History of Ethernet Standards • Ethernet – The dominant wired LAN technology today – Only “competitor” is wireless LANs (which actually are supplementary) • The IEEE 802 Committee – LAN standards development is done primarily by the Institute for Electrical and Electronics Engineers (IEEE) – IEEE created the 802 LAN/MAN Standards Committee for LAN standards (the 802 Committee)

Figure 4-1: A Short History of Ethernet standards The 802 Committee creates working groups for specific types of standards 802. 1 for general standards 802.3 for ethernet standards The terms 802. 3 and ethernet are interchangeable 802 11 for wireless lan standards 802.16 for WiMax wireless metropolitan area network standards

4-4 Figure 4-1: A Short History of Ethernet Standards • The 802 Committee creates working groups for specific types of standards – 802.1 for general standards – 802.3 for Ethernet standards • The terms 802.3 and Ethernet are interchangeable – 802.11 for wireless LAN standards – 802.16 for WiMax wireless metropolitan area network standards

Figure 4-1: A Short History of Ethernet standards Ethernet standards are osi Standards Single networks, including LANS, are governed by physical and data link layer standards Layer 1 and Layer 2 standards are almost universally OSI standards Ethernet is no exception The IEEE makes 802.3 standards: Iso ratifies them In practice, when 802.3 finishes standards, vendors begin building compliant products 4-5

4-5 Figure 4-1: A Short History of Ethernet Standards • Ethernet Standards are OSI Standards – Single networks, including LANs, are governed by physical and data link layer standards – Layer 1 and Layer 2 standards are almost universally OSI standards – Ethernet is no exception – The IEEE makes 802.3 standards; ISO ratifies them – In practice, when 802.3 finishes standards, vendors begin building compliant products

Test Your Understanding ·P188 ·2 4-6

4-6 • Test Your Understanding • P 188 • 2

Ethernet Physical Layer Standards

Ethernet Physical Layer Standards

Figure 4-3: Baseband versus broadband Transmission Baseband transmission Signal Transmitted Signal (same) Source Transmission Medium Signal is injected directly into the transmission medium (wire, optical fiber) Inexpensive, so dominates wired Lan transmission technology BASE in standard names means baseband 4-8

4-8 Figure 4-3: Baseband Versus Broadband Transmission Baseband Transmission Source Signal Transmitted Signal (Same) Transmission Medium Signal is injected directly into the transmission medium (wire, optical fiber) Inexpensive, so dominates wired LAN transmission technology BASE in standard names means baseband

Figure 4-3: Baseband versus broadband Transmission, Continued Broadband transmission L Modulated Signa Radio channel Source Radio Tuner The radio tuner modulates the signal to a higher frequency The transceiver then sends the signal in a radio channel Expensive but needed for radio-based networks Not used in Ethernet, but is used in wireless LANs(discussed in Chapter 5) 4-9

4-9 Figure 4-3: Baseband Versus Broadband Transmission, Continued Broadband Transmission Source Radio Tuner Modulated Signal Radio Channel The radio tuner modulates the signal to a higher frequency. The transceiver then sends the signal in a radio channel. Expensive but needed for radio-based networks. Not used in Ethernet, but is used in wireless LANs (discussed in Chapter 5)

I Figure 4-2: Ethernet Physical Layer Standards UTP Physical Speed Maxim um Medium Layer Run Required Standards Leng 10BASE-T 10 Mbps 100 meters 4-pair Category 3 or higher 100BASE-TX 100 Mbps 100 meters 4-pair Category 5 or higher 1000BASE-T 1,000 Mbps 100 meters 4-pair Category 5 or higher (Gigabit Ethernet) 100BASE-TX dominates access links today, Although 1000BASE-T is growing in access links today 4-10

4-10 Figure 4-2: Ethernet Physical Layer Standards UTP Physical Layer Standards Medium Required Maximum Run Length Speed 100BASE-TX 100 Mbps 100 meters 4-pair Category 5 or higher 1000BASE-T (Gigabit Ethernet) 1,000 Mbps 100 meters 4-pair Category 5 or higher 10BASE-T 10 Mbps 100 meters 4-pair Category 3 or higher 100BASE-TX dominates access links today, Although 1000BASE-T is growing in access links today