Category Archives: networking

IS-IS vs. OSPF Part II:  Small steps make steady progress

IS-IS Subnetwork Independent Operation

Continuing our journey through the land of IS-IS and hoping to reach the point where we get to understand how it actually works and the differences between it and OSPF, let’s focus today on how IS-IS is configured and why it uses both Levels and Areas.

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OSPF Forwarding Address Part III: The perfect recipe for chaos

After getting familiar with the FA, when it’s set and when not, we’re ready to cook the recipe for chaos: NSSAs, Default Route injection and Forwarding Address.

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IS-IS vs. OSPF Part I: First steps in understanding IS-IS

The theme question is actually quite a good one, because it may seem like the fight has already been won by IS-IS in the Service Provider segment, and by OSPF on the enterprise market. So why ask it then? Well, because I got the following answer one too many times: “IS-IS is awesome, OSPF not so much. I have no idea how IS-IS works but it’s great. OSPF is so complicated and offers so little flexibility…”.

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BGP in Large Scale Data Centers with Clos Networks

Getting to the point where big is never big enough, one may think “What’s cooking?” Well, BGP in the DC is a subject that’s been under my radar for some time, so the purpose of this article is to get things a bit more straight-forward regarding the WHYs and HOWs.

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OSFP Forwarding Address Part II: Redistribution and filtering don’t get along very well

Hoping you all enjoyed the first part of the OSPF forwarding address saga, I’m back with the promise to make things clear regarding a nicely built redistribution case. I’m not sure if you’ve ever come across it, or ever will, but it’s interesting because it explains why we need the rules to set the forward address (if you don’t remember them, you can take a look at Part I).

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OSFP Forwarding Address Part I: Type 5 LSA Suppression

OSPF (Open Shortest Path First) is mostly seen as a pretty nasty routing protocol, with a load of subtleties and corner cases. I’ve decided to talk about a subject which usually gives a lot of troubles to most network professionals – the Forwarding Address (FA).

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