The Open Shortest Path First (OSPF), as you already know, uses the link state routing algorithm and operates on a singular Autonomous System (AS). OSPF could very easily be the most widely accepted and used Interior Gateway Protocol (IGP), especially in large enterprise networks. Therefore, for being a successful networker, it is critical that you are familiar with OSPF, and particularly point-to-point OSPF networks. In OSPF routing protocol, the routing structure is based on the shortest network path tree, and this shortest path is calculated using Dijkstra’s algorithm. The video aims at showing light on point-to-point OSPF networks, their configuration, associated problems, and helps you to distinguish and identify the different routers in the network.
Proper Identification
The point-to-point OSPF network is the simplest OSPF network type. There is direct point-to-point link between two different routers, and there is no need for the presence of a DR and a BDR. When it comes to directly connected interfaces, it is already known that for two connected routers, as shown in the very first image in the video, both of these routers act as DTE when connected through Serial 1 interfaces. But in case of directly connected routers, one of the two routers needs to act as the DCE, which is used to supply the clock rate. The two routers are connected with the help of a DTE-DCE cable. Identifying which end of the cable is the DCE, and consecutively the other DTE, is not a task which you can complete by merely looking at the cable.
Not properly identifying the DTE and DCE routers can lead to various configuration problems.
The DTE or DCE
In order to recognize the router, the command routernumber#show controller should be implemented, followed by the type of interface and the router number. Using this command, you can easily conclude whether that particular end is the DTE or the DCE.
The Main Theme
In order to successfully implement point-to-point OSPF networks, you have to lay heavy emphasis on the commands you type in. However, if you do make a mistake somewhere, a ‘^’ marker indicates the exact location where your code is faulty. Another very important requirement is after you have identified the DCE end, you have to supply it with proper clock rate. When this video ends, you should find it easier to identify the DCE-DTE connections, supplying DCE clock rate and configuring the routers.
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