What is OSPF and How Does It Work?

In this video, Keith Barker covers OSPF, the protocol that makes it possible for your routers to forward traffic all the way through your network. There are a lot of different topics to deal with when you break down OSPF, but Keith covers them with easy examples and simple demonstrations:

Start off with a sample network topology to visualize how OSPF works on it

Breaking down how LSAs make OSPF possible

How Link State Databases provide routers with all the network information they need

OSPF Hello messages and how they help routers share data

Visualizing the sort of network that OSPF would be useful for can help understand exactly how it does that. Keith starts with a sample network topology and splits it into areas. Different routers provide access to different areas, and eventually they'll become OSPF neighbors.

But before you get to that, it's important to understand Link State Advertisements (LSA). When you have a network topology with multiple zones, the connecting routers are responsible for creating an LSA and broadcasting them. LSAs contain all the information about the networks that each router services.

With OSPF, it's possible for routers to "meet" one another, send "hello"s to one another and share their link state information. Link State Databases are shared between OSPF routers, and in turn those routers leverage the data inside those databases to make decisions about routing data across the entire network.

OSPF is the language that makes it possible for all the routers across a network to collaborate like this. It also makes it possible to carve the network up into smaller chunks so that you don't have to create routing tables for every last destination in the network on every single router.

Start learning with CBT Nuggets:

[prafullpandit]

I always sensed his passion for networking concepts when listening to the audios and now watching him explain these concepts, in the way he does it, confirms my belief. Hands down the best Trainer/Instructor/Mentor when it comes to Networking.

[sabhareeshwaran]

One of the best teacher in CBT nuggets is you sir...👍

[babar]

Today, first time I have cleared the concept of LSA and ABR how it should work in the OSPF routing protocol. Neighbors are the routers in each area... I have cleared concept eventually. Thanks so much.

[arsenmkrtchyan]

Best as always. Great job Keith and thank you !

[satyamdubey]

OG of IT for a reason! Thanks Keith for the nugget.

[nickwhite]

The cup analogy is very helpful in explaining LSAs and Database per routing and how they are shared well done.

[pleego]

Your videos are amazing. Thank you so much for sharing your insane depth of knowledge, in such a fun and simple way! I understood instantly concepts that I thought were really hard.

[owzy]

This channel deserves more subs! Thanks, Keith!

[MrAmirkhan]

wonderful to listen and revise concepts, thanks

[ChrisB-fjjk]

You are the hero I needed man! Thanks for this.

[yumsai]

That is the best explanation of OSPF I have ever seen... You are a master of your

[mdezer]

Thanks for this! Great explanation on how OSPF works.

[coxixx]

Hi Boss, you are the best teacher of networking in the world.

[andrepotts]

WOW this is my first time viewing your videos and I must compliment you, the friendly and helpfull person you are has helped me understand the meaning of OSPF, i wil subscride and share your link.

[naesone]

what a great and passionate explenation

[jeffwise]

man id love to have a beer or 6 with you!!! Thanks you are making this easy and fun!!

[Jeancomputech]

Great video i do have a question between area 0 and area 1 is that a BGP protocol between them?

[icysaracen]

Struggled with OSPF in my network course - Wish my teacher used props to make it so easy to understand.

[pathlabdotline]

Thanks Keith for the nugget. Could you please make a nugget on PPP and HDLC WAN protocols ?

[placidemutuyimana]

is this Jeremy I always followed back in 2010's !!!