McGraw-Hill©The McGraw-Hill Companies, Inc. Chapter 9 Local Area Networks Part I: Basic Concepts and Wired Ethernet LANs

McGraw-Hill©The McGraw-Hill Companies, Inc. Understand the use of LANs in an organization. List the components of a LAN. Be familiar with the IEEE standards. Be familiar with traditional Ethernet technology and its implementations. After reading this chapter, the reader should be able to: O BJECTIVES Be familiar with Gigabit Ethernet technology and its implementations. Be familiar with Fast Ethernet technology and its implementations.

McGraw-Hill©The McGraw-Hill Companies, Inc. BASICCONCEPTSBASICCONCEPTS 9.1

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-1 A client-server model with dedicated servers

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-2 A client-server model with a general server

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-3 Peer-to-peer model

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-4 Physical bus topology

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-5 Physical star topology

McGraw-Hill©The McGraw-Hill Companies, Inc. The star topology is the dominant physical topology today. Note:

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-6 Logical bus topology

McGraw-Hill©The McGraw-Hill Companies, Inc. In 1985, the Computer Society of the IEEE developed Project 802. It covers the first two layers of the Internet model. Note:

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-7 Logical star topology

McGraw-Hill©The McGraw-Hill Companies, Inc. 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:

McGraw-Hill©The McGraw-Hill Companies, Inc. Project 802 has split the data link layer into two different sublayers: logical link control (LLC) and media access control (MAC). Note:

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-8 LAN compared with the Internet model

McGraw-Hill©The McGraw-Hill Companies, Inc. WIREDETHERNETLANsWIREDETHERNETLANs 9.2

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-9 Collision in CSMA/CD

McGraw-Hill©The McGraw-Hill Companies, Inc. 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.

McGraw-Hill©The McGraw-Hill Companies, Inc. 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.

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-10 Implementations of Ethernet

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-11:a Ethernet connection to the medium

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-11:b Ethernet connection to the medium

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-11:c Ethernet connection to the medium

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-11:d Ethernet connection to the medium

McGraw-Hill©The McGraw-Hill Companies, Inc. Technical Focus: Ethernet Frame Traditional Ethernet has a frame with the following format:

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-12 Switched Ethernet

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-13 Fast Ethernet implementations

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-14:a Fast Ethernet connection to the medium

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-14:b Fast Ethernet connection to the medium

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-14:c Fast Ethernet connection to the medium

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-15 Gigabit Ethernet implementations

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-16:a Gigabit Ethernet connection to the medium

McGraw-Hill©The McGraw-Hill Companies, Inc. Figure 9-16:b Gigabit Ethernet connection to the medium

McGraw-Hill©The McGraw-Hill Companies, Inc. 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.