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Bridging and Switching

Bridges and switches are both layer-2 devices, functioning at the data link layer of the OSI Reference Model. Even though they are both layer-2 devices and have many similarities between them, they also have many differences. With advancements in hardware and technology, switches perform faster and have many more features. However, the basic functions of these two devices are the same. This chapter covers the functions of bridges and switches, the Spanning Tree Protocol (STP), and basic switch configuration tasks on Cisco’s Catalyst 1900 and 2950 | CCNA CISCO CERTIFIED NETWORK ASSOCIATE 7 Bridging and Switching CERTIFICATION OBJECTIVES 7.01 7.02 7.03 Bridges and Switches Functions of Bridging and Switching The Spanning Tree Protocol 7.04 Q A 1900 and 2950 Configuration Two-Minute Drill Self Test 2 Chapter 7 Bridging and Switching Bridges and switches are both layer-2 devices functioning at the data link layer of the OSI Reference Model. Even though they are both layer-2 devices and have many similarities between them they also have many differences. With advancements in hardware and technology switches perform faster and have many more features. However the basic functions of these two devices are the same. This chapter covers the functions of bridges and switches the Spanning Tree Protocol STP and basic switch configuration tasks on Cisco s Catalyst 1900 and 2950. CERTIFICATION OBJECTIVE 7.01 Bridges and Switches The main function of bridges and switches is to solve bandwidth or collision problems. Remember that in Ethernet multiple devices can share the same segment so there is a chance that more than one device might try to transmit at the same time creating a collision and a retransmission. The more devices you have in a shared medium the more likely collisions will occur. This doesn t mean that Ethernet is a bad data link layer topology it s just the way it functions. In the old days of networking you used hubs to connect devices together or used 10Base5 or 10Base2 cabling where you would have many devices on one wire . If you experienced constant or excessive amounts of collisions you could use bridges and later on switches to break up the user devices to multiple segments where each segment would have fewer users and thus fewer collisions. You could also use a router to perform this function however the disadvantage of a router is that it costs a lot more than a bridge or switch. This section provides a brief overview of bridges and switches. Bridging Versus Switching Even though bridges and switches .