OSPF Router Types Cisco CCNP / BSCI Exam Tutorial

OSPF Router Types Cisco CCNP / BSCI Exam Tutorial
An OSPF Internal router has three rule - it must have all its interfaces in a single area. It does not mean that area has to be Area 0.

When you are preparing to pass the BSCI exam on the way to the coveted Cisco CCNP certification, you can be quickly overwhelmed by the sheer amount of BGP & OSPF knowledge you must demonstrate a mastery of. three set of details that some BSCI & CCNP candidates underestimate are the differences between the OSPF router types.

An OSPF Backbone router is a router with at least a single area in the OSPF backbone area, Area 0. A router can be both an Internal & Backbone router if all its interfaces are in Area 0.

An Area Border Router has at least three interface in Area 0 & another interface in a non-backbone area. ABRs are also three of three router types that can perform OSPF route summarization. (To advertise a summary route from three OSPF area to another, use the area range command on the ABR.)

there's several commands you can use to determine the router types in a given OSPF area. The command "show ip ospf" will display a bit of information regarding the local router, & this includes whether that router is acting as an ABR or ASBR. To see the routes to the ABRs & ASBRs from the local router, run "show ip ospf border-routers".

Finally, an ASBR is an OSPF router that is performing route redistribution by injecting routes from another source into the OSPF domain. This is the other OSPF router type that can perform route summarization; to summarize routes being redistributed into OSPF, use the summary-address command on the ASBR.