ccna zusammenfassung pdf

ccna zusammenfassung pdf.A section focusing on switches and protocols running at Layer 2 moves up one layer along the OSI reference model, with the goal of discussing Layer 3, the network layer.layer, the network layer. Layer 3 devices are collectively referred to as routers. Routers basically have two functions: . Find the Layer 3 path to the destination network; . Move packets from one interface to another in order to transmit them to their destination. To perform the first function, the router needs to do the following: . Learn which routers it is connected to in order to determine which networks are reachable; . Find out the location of the destination network; . Select the best path to the destination network; . Maintain up-to-date routing information about how to get to the destination network.Exam Points Be sure to know the functions of routers: they learn about neighboring routers, find and select the best path to the destination network, and maintain up-to-date reachability information.To perform the second function, routers need to look at the destination IP address in the inbound IP packet, determine the network number of the destination, and look in the routing table and exchange the packet to the outbound interface.As you will see in this chapter, the routing table contains a list of destination network numbers, the status of those networks, which interface should be used to go to the destination network, and which neighboring router should be used to go to the destination network if it is more than one hop away. This chapter briefly introduces routing and the dynamic routing protocol types: distance vector, link state, and hybrid protocols.Exam Points Don't forget that for routing packets, the router must determine the destination network number in the destination address field in the IP header and look it up in the routing table.Authentication Targets 14.0114.1 Introduction to RoutingBefore discussing routers and routing protocols, you must have a general understanding of: what types of routes a router can contain; and how a router uses the routes it learns about. The next few subsections discuss the two methods of learning about routes (static and dynamic), how routers are grouped (autonomous systems), and the trade-offs that routers make when choosing from among the paths offered by multiple routing protocols.14.1.1 Types of Routing