BROCADE IP PRIMER

Chapter 11: Open Shortest Path First (OSPF)• Type 7 (NSSA). These are sent by an ASBR in an NSSA to the ABR withintheir respective area; the ABR will then translate the Type 7 to a Type 5,and advertise it to Area 0 (which will propagate it from there); becauseany other area would see this as a Type 5, Stub Areas, Totally StubbyAreas, and even other NSSAs would not see these LSAsConfiguring OSPFFor as complicated as the OSPF protocol is, configuring it is surprisingly easy.The first thing you have to do is enable it globally:BR-Switch#conf tBR-Switch(config)#router ospfNext, you have to specify the areas that the router will be participating in. Youcan list as many areas as the router will be participating in, but for this example,I'll just put it in Area 0:BR-Switch#conf tBR-Switch(config)#router ospfBR-Switch(config-ospf-router)#area 0Finally, you must configure the router interface with the OSPF area that its participatingin. Say, for example, that interface e 5 had an IP address configuredon it, and you want it participating in Area 0:BR-Switch#conf tBR-Switch(config)#int e 5BR-Switch(config-if-e1000-5)#ip ospf area 0As soon as that last command is issued, OSPF is fully enabled, and Hello packetswill be sent out interface “e 5” to start the neighboring process. You couldalso define the router's priority. This is done at the interface config:BR-Switch#conf tBR-Switch(config)#int e 5BR-Switch(config-if-e1000-5)#ip ospf priority 100What if you want an interface to be part of OSPF, but you don't want it to sendor receive routing updates? This is what is called a passive interface. It is configuredlike this:BR-Switch#conf tBR-Switch(config)#int e 5BR-Switch(config-if-e1000-5)#ip ospf passiveLoopback InterfacesIt is often very wise to configure a loopback interface on the router that is participatingin OSPF. Why? Well, the loopback address doesn't belong to aparticular interface. If you have a router participating in OSPF with severalphysical links, the router will have to be identified by the IP address of one ofthose links (the Router ID). What if that link goes down? You have to start theneighboring process all over again using a new Router ID.250 Brocade IP Primer