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Copyright 2003 By Your Name CCNA 3 Chapter 1 Review: The OSI Reference Model and Routing
Copyright 2003 Objectives Describe the overall function of the OSI reference model and the problems it solves Describe the characteristics of the: –OSI physical layer –OSI data link layer –OSI network layer –OSI transport layer Describe the function of routing in networks Understand the different classes of routing protocols
Copyright 2003 Types of Ethernet Ethernet and IEEE LAN specifications, which operate at 10 Mbps over coaxial and twisted- pair cable. 100-Mbps Ethernet A single LAN specification, also known as Fast Ethernet, which operates at 100 Mbps over twisted-pair cable Mbps Ethernet A single LAN specification, also known as Gigabit Ethernet, which operates at 1000 Mbps (1 Gbps) over fiber and twisted-pair cables. 10 Gigabit Ethernet is only supported over fiber optic media.
Copyright 2003 Three Varieties of 10 Mbps Ethernet 10BASE-2 –Known as thin Ethernet or thinnet –Allows network segments up to 185 meters on coaxial cable 10BASE-5 –Known as thick Ethernet or thicknet –Allows network segments up to 500 meters on coaxial cable 10BASE-T –Carries Ethernet frames on inexpensive twisted- pair wiring
Copyright 2003 Path Switching The network layer (3) address does not change. The data link layer (2) MAC address changes for each segment.
Copyright 2003 Static Versus Dynamic Routes The purpose of a static route Why dynamic routing is necessary Dynamic routing operations How distances on network paths are determined by various metrics Classes of routing protocols Time for convergence
Copyright 2003 Routing Protocols A routing protocol defines the set of rules used by a router when it communicates with neighboring routers, including the following: –How to send updates –What knowledge these updates contain –When to send this knowledge –How to locate recipients of the updates
Copyright 2003 Distance Vector Routing Basics Routing updates explained The problem of routing loops The problem of counting to infinity Link-state routing basics How link-state protocols exchange routing information How topology changes propagate through the network of routers