Routing Protocol

Configurating OSPF

Now that you have OSPF's key concepts and terminology mastered, you are ready to configure OSPF. Configuring OSFP on a Cisco routers entails two main steps 1. Enable OSPF with the router ospf < process id> command. 2. Identify the interfaces that will be OSPF with the network address wildcard mask area command. The wildcard mask indicates which bits are pertinent (0 bits) and which bits aren't (1 bits). For example, the wildcard mask 0.0.255.255 indicates that the router must match the...

Configurating RIP I and II

RIP is easy to configure, you start RIP with the IOS command router rip and then apply the networks you want to be advertised. The IOS command to enable the local network within RIP is For illustrative purposes, let's configure the network shown in Figure 6.1 for IP RIP version I. Then, we can modify the configuration to enable RIP II. In order to get our RIP network operating, a few steps will need to occur so let's briefly discuss them. First, we will need to start the RIP routing process on...

Area Border Routers ABRs and Virtual Links

As previously mentioned, OSPF uses areas to limit memory and CPU requirements. A that router can be in one area is termed an internal router, a router in multiple areas is termed an area border router. A router that is also part of another routing domain is termed an autonomous system area border router (ASBR). Finally, there is another area in OSPF that is usually present in all networks the backbone area, or the area designated as Area 0. Areas are used to stop the explosion of link-state...

Configuration of ISIS

To enable ISIS on a Cisco router, you must perform the following configuration tasks Enable ISIS with the router isis command. Configure ISIS interface parameters. Configure any miscellaneous parameters. The three methods (referred to as network entitieS) used to define an ISIS area and their field formats are Simple Area System ID SEL OSI Domain Area System ID SEL GOSIP AFI ICD DFI AAI Reserved RDI Area System ID SEL The meaning of each network entity field is defined as follows AFT Authority...

Configuration of IGRP

For this section, let's revisit Figure 6.1 and use IGRP instead of RIP, with AS number 1. The configuration command required on all four routers is Listing 6.8 displays router R1's routing table. Listing 6.8 The show ip route command after configuring IGRP on R1. 10.0.0.0 24 is subnetted, 9 subnets C 10.1.9.0 is directly connected, Ethernet0 C 10.1.8.0 is directly connected, Serial0 I 10.1.3.0 100 158350 via 10.1.8.2, 00 00 01, Serial0 I 10.1.2.0 100 160250 via 10.1.4.2, 00 00 01, Serial2 100...

Open Shortest Path First OSPF

Open Shortest Path First (OSPF) is a link-state protocol used by internal networks. This means that OSPF distributes information between routers belonging to the same autonomous system. OSPF runs over IP enabled networks and OSPF has been defined in many RFCs over the years. OSPF was originally developed in RFC 1131, and its most recent specifications are in RFC 2328. OSPF was designed to handle large IP networks and manage them into smaller networks called areas. Areas are used to reduce...