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Explore LAN components, IEEE standards, Ethernet technologies, and their implementations. Learn about LAN use in organizations and different network topologies. Dive into Ethernet addressing, signaling, and frame formats. Technical insights on collision detection and Token Ring networks.
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Chapter 9 Local Area Networks Part I: Basic Concepts and Wired Ethernet LANs
OBJECTIVES List the components of a LAN. Be familiar with the IEEE standards. Be familiar with traditional Ethernet technology and its implementations. Be familiar with Gigabit Ethernet technology and its implementations. Be familiar with Fast Ethernet technology and its implementations. Understand the use of LANs in an organization. After reading this chapter, the reader should be able to:
9.1 BASIC CONCEPTS
Figure 9-1 A client-server model with dedicated servers
Figure 9-2 A client-server model with a general server
Figure 9-3 Peer-to-peer model
Figure 9-4 Physical bus topology
Figure 9-5 Physical star topology
Note: The star topology is the dominant physical topology today.
Figure 9-6 Logical bus topology
Note: In 1985, the Computer Society of the IEEE developed Project 802. It covers the first two layers of the Internet model.
Figure 9-7 Logical star topology
Technical Focus:Ring Topology Another physical topology common at the beginning of the LAN era was the ring topology. In a ring topology, each station is connected to the next station as shown in the following figure:
Note: Project 802 has split the data link layer into two different sublayers: logical link control (LLC) and media access control (MAC).
Figure 9-8 LAN compared with the Internet model
9.2 WIRED ETHERNET LANs
Figure 9-9 Collision in CSMA/CD
Technical Focus:Ethernet Addressing Each station on an Ethernet network (such as a PC, workstation, or printer) has its own network interface card (NIC). The NIC usually fits inside the station and provides the station with a 6-byte (48-bit) physical address.
Technical Focus:Signaling Traditional Ethernet uses Manchester digital encoding (discussed in Chapter 6). In this type of signaling, the transition at the middle of each bit is used for synchronization between the sender and receiver.
Figure 9-10 Implementations of Ethernet
Figure 9-11:a Ethernet connection to the medium
Figure 9-11:b Ethernet connection to the medium
Figure 9-11:c Ethernet connection to the medium
Figure 9-11:d Ethernet connection to the medium
Technical Focus:Ethernet Frame Traditional Ethernet has a frame with the following format:
Figure 9-12 Switched Ethernet
Figure 9-13 Fast Ethernet implementations
Figure 9-14:a Fast Ethernet connection to the medium
Figure 9-14:b Fast Ethernet connection to the medium
Figure 9-14:c Fast Ethernet connection to the medium
Figure 9-15 Gigabit Ethernet implementations
Figure 9-16:a Gigabit Ethernet connection to the medium
Figure 9-16:b Gigabit Ethernet connection to the medium
Technical Focus:Token Ring Networks At the beginning of the LAN era, a LAN technology called Token Ring was developed that uses a token passing method. Whenever the network is unoccupied, a token circulates freely from one station to another. When a station has data to send, it captures the token and sends its frame.
