Being that it has been quite awhile since my ROUTE, this will contain a lot of core / foundation concepts, and tie them into troubleshooting as I go. That said, here we go! OSPFv2 (IPv4) review and troubleshooting OSPF is configured with a Process # that is locally significant only "router ospf #" and networks … Continue reading TSHOOT – OSPFv2, OPSv3, OSPF Address-Families, huge LSA / LSDB review, and troubleshooting everything OSPF!
Apologies for how terrible the Topology is, I took an existing picture and put some purple arrows leading off the ABR's, indicating that this is actually where Type 4 LSA's are created. Now ASBR's create Type 5 LSA's which of course are External / Redistributed routes which are shared throughout the entire routing domain across … Continue reading OSPF: Type 4 LSA’s, who creates them, why they create them, a relatively shorter post for once!
Sticking with this Topology in case I need to lab something for demonstration, it is clear what routers are where. To begin, every router within any given Area should have an identical copy of the LSDB, and that only Type 1 and Type 2 LSA's are flooded only within the Area they originated. The Database … Continue reading OSPF: Database Exchange Process including messages, neighbor states, and all things neighbor forming related!
When you first configure a router in an Area via an OSPF instance, you are creating a Link State Database, that already contains entries for different LSA Types. Each router considers itself to be the Root of what is called the "Shortest Path First Tree", which is a mapping via LSA's from neighbor routers, which … Continue reading OSPF: LSA Type 1 (why it’s unique), explanation of SPF Tree, and a handy show command for exam day!
Since I already have the lab configured with different OSPF Area's, and we had a riveting exploration into the world of LSA's and the LS DB of each router, I wanted to hit some other topics again thoroughly before I switch up protocols for more DEEP Dives into all things CCNP ROUTE related! Without further … Continue reading OSPF: DEEP Dives into Summarization methods, Authentication, Default-Information Originate (Always)!
To lead off where we left, we made Area 15 an NSSA Area which stopped the Type 4 and 5 LSA's from entering the Area, now we are going to do some Redistribution the other way and turn R5 in the NSSA Area into an ASBR. I've created networks (loopbacks) 18.104.22.168 /32 and 22.214.171.124 /24, … Continue reading Part 3: OSPF LSA DEEP Dive LSA Type 7, DEEP Dive into OSPF Stub and NSSA Areas, and how they impacts LSA traffic!
I will start this off by stating that we will start redistribution on the ASBR specified R2 to examine LSA types 4 and 5 (and where we can spot them), and R1 will eventually also be turned into an ASBR when we redistribute some loopback routes into the NSSA Area so we can review type … Continue reading Part 2: OSPF LSA DEEP Dive, LSA Types 4 / 5, and turn Area 15 to an NSSA to see what happens with the LS Database!
So we are back to OSPF, as I never really went into a deep dive with LSA types, or the LSA DataBase from different routers to show their perspective of the OSPF network caused by these Link State Advertisements. I've only configured base OSPF and RIP configurations in this lab so far, the above Topology … Continue reading Part 1: OSPF LSA DEEP dive, starting with LSA Types 1 / 2 / 3, and an Intro to all LSA Types and OSPF Routers types!
This will be another bullet point style post, as I have not fully delved into these LSA types with labs yet. One thing I have noticed, "show ip ospf database" will not give you the LSA type or number just in one of the columns of the output, they will need to be known by … Continue reading OSPF Router and LSA Types