Continuing with our discussion of OSPF summarization options, refer to the figure below… When we left off, we had reduced the number of Type-5 LSAs being injected into the OSPF cloud from two hundred to two, a summary route from each ASBR. But what if the prefixes that lie within the RIP or EIGRP clouds […]

Having discussed how OSPF works without summarization options, let’s take a look at the various summarization options and their effects. If there are 100 prefixes in the RIP cloud, and another 100 in the EIGRP cloud, each being injected into the OSPF domain by the ASBRs, each OSPF router will be tracking over 200 individual prefixes, […]

Having discussed OSPF route summarization and the various types of stub areas, let’s look at the potential drawbacks of using those features. We’ll start by reviewing how OSPF acts before any summarization features are configured. Refer to Figure 1: As you can see, R3 connects Area 0 and Area 1 together, making R3 an OSPF […]

Yep, we’re up to part seven … there is a lot you can do with OSPF! For this discussion, we’ll use the example topology shown in Figure 1. From here, we can see that R2, R3 and R5 are ABRs (connecting OSPF areas), and that R5 and R6 are ASBRs (connecting the OSPF autonomous system […]