Recent posts

A Deep Dive in OSPF LSAs, Part 5

April 24, 2015 | 5 minute read

In Part 3 I demonstrated how you can use Type 1 and Type 2 LSAs to map the topology an OSPF area. In this post we’ll do the reverse. By looking at a network diagram below, you should be able to determine the following: Who will be sending Type 1 LSAs? How many Type 1 LSA entries will there be? What will the “Link Count” be for each of th...

A Deep Dive in OSPF LSAs, Part 4

April 23, 2015 | 4 minute read

As mentioned a couple of times in this series, Type 1 LSAs differ between Broadcast and Point-to-Point segments. To demonstrate this, I’ll be using the same topology as before. The only difference is that each interface has had the “ip ospf network point-to-point” command applied to it. You may recall that the reason why I’m talking only abou...

A Deep Dive in OSPF LSAs, Part 3

April 23, 2015 | 4 minute read

In my previous post I covered Type 1 and Type 2 LSAs in relation to broadcast networks. In this post I’ll demonstrate how you can use these LSAs to map the topology an OSPF area. Broadcast Networks - Type 1 + Type 2 LSAs = Area Diagram First, let’s take a look at which LSAs exist in this area: R1(config-if)#do sh ip ospf database ...

A Deep Dive in OSPF LSAs, Part 2

April 22, 2015 | 7 minute read

In my previous post I covered the inspiration for this series of posts as well as many of OSPF’s LSAs. Now that we’ve got the boring stuff out of the way, let’s jump into the fun stuff :) In this post I’ll cover Type 1 and Type 2 LSAs in broadcast networks. The reason why I highlight the fact that this information applies only to broadcast netw...

A Deep Dive in OSPF LSAs, Part 1

April 22, 2015 | 2 minute read

Configuring an OSPF network can be very easy. Within a couple of commands you can have a fully functioning network. While being easy to configure is definitely a pro, the con is that you don’t actually need to understand how it works in order to use it. Why is this a problem you ask? Well, how can you troubleshoot something you don’t understand?...