The administrative distance is the way routers use to give preference to routing sources. What if we had configured several routing protocols on one router, how would the router determine the best path to the desired network? Understanding the different costs types will be crucial in your final exam. The bandwith or cost configured from the router to the destination network The composite metric will be discussed in the chapter on EIGRP. The number of routers between the source and destination network.Ī combination of several values used to determine the best path. The table below shows the various metrics used by routing protocols which will be covered in this course. The metric is used to determine the best path to a network when there are multiple paths. In the tourist example, this may be the amount of fuel the tourist has to use to get to their destination. The metric, is the mechanism used by the routing protocol to assign costs to reach remote networks. Suppose a router has more than 1 destination to a network, how would it determine the best path to that network? Administrative distance and metric Metric In this course, we will focus on the classless routing protocols since the use of classful routing protocols is outdated and no longer used in most modern networks. Classless routing protocolsĬlassless routing protocols include the subnet mask with the network address in routing updates. Since they do not include the subnet mask in their routing updates, they cannot work where the networks have been subnetted. This is because they were designed prior to the introduction of CIDR and VLSM. Interior Gateway Protocols (IGPs) can be classified as two types:įast convergence of the network is crucial.Ĭlassful and classless Classful Routing ProtocolsĬlassful routing protocols don’t include the subnet mask in their routing updates. In this scenario for example, routing between XYZ headquarters and the branch office would use and IGP, whilst routing between company XYZ and the ISP would use an EGP. Interior Gateway Protocols (IGP) are used for intra-autonomous system routing – routing inside an autonomous system.Įxterior Gateway Protocols (EGP) are used for inter-autonomous system routing – routing between autonomous systems. The networks controlled by XYZ are labelled as AS 100 while AS 650 represents the ISP. The networks owned and managed by XYZ would be one autonomous system, while the leased line and interconnections between the branch office and the headquarters which are controlled by the ISP would be another autonomous system. This may mean the routers that are owned by one company.įor example, company XYZ, could have 1 branch connected to the headquarters through a leased line. This categorization, is based on the Autonomous Systems.Īutonomous systems also known as routing domains are collections of routers under the same administration. Classificationĭynamic routing protocols can be classified in several ways. This information is then added to their routing tables as a basis for forwarding packets. Routing protocols are used to enable the routers exchange routing information, they allow routers to learn about remotely connected networks dynamically. In most networks you will see a mix of both dynamic and static routes.
Examples of routing protocols how to#
Wouldn’t it be much easier, for the network administrator to just “Teach” the routers how to get from one point to another? The solution to this problem would be dynamic routing protocols.ĭynamic routing protocols are a solution that is used in large networks so as to reduce the complexity in configuration that would be occasioned by having to configure static routes. All the static routes would have to be configured. The administrative overhead that would be needed to make communication between all these devices would be considerable. We will also talk about the administrative distance and the metric.Ĭonsider the network diagram shown below. We will discuss their advantages over static routes, learn the different categories of dynamic routing protocols as well as classless and classful nature. We will define them and learn how they are different from static routes. In this chapter, we will give an overview of dynamic routing protocols. We configured static routes and traffic was able to flow between two points. We saw how the router finds the best path to a network. In the previous chapter, we looked at static routing.