Jan
03
Continuing my review of titles from Petr’s excellent CCDE reading list for his upcoming LIVE and ONLINE CCDE Bootcamps, here are further notes to keep in mind regarding EIGRP. About the Protocol The algorithm used for this advanced Distance Vector protocol is the Diffusing Update Algorithm. As we discussed at length in this post, the metric is based upon Bandwidth and Delay values. For updates, EIGRP uses Update and Query packets that are sent to a multicast address. Split horizon and DUAL form... Read More
Dec
30
To start my reading from Petr's excellent CCDE reading list for his upcoming LIVE and ONLINE CCDE Bootcamps, I decided to start with: EIGRP for IP: Basic Operation and Configuration by Russ White and Alvaro Retana I was able to grab an Amazon Kindle version for about $9, and EIGRP has always been one of my favorite protocols. The text dives right in to none other than the composite metric of EIGRP and it brought a smile to my face as I thought about all of the misconceptions I had regarding... Read More
Dec
23
CCNA students can typically rattle off the fact that EIGRP uses Bandwidth and Delay in its composite metric calculation by default. In fact, they tend to know this as well as their own last name. But I often notice they might have some pretty big misconceptions about how this metric is really calculated, and how they can manipulate it. Here are some very important "Core Knowledge" facts that we need to keep in mind about the EIGRP metric: Read More
Aug
05
As a former English Major at the University of Massachusetts, Amherst, I really loved the oxymoron. You remember those..."sharply dull" or "cruel kindness". Well, the OSPF protocol has one whopper of an oxymoron in its special areas - The Totally, Not-So-Stubby area! When we last left our Area 11 in Part 4 of this blog series, it was a Not-So-Stubby Area, with the default-information-originate command used on the Area Border Router (ABR) in order to ensure a default route existed in the area.... Read More
Jul
31
Click here for Part 1 of the series or click here for Part 3 of the series. Now it is time for us to examine yet another OSPF special area type - the Not-So-Stubby Area. I am sure you recall out topology from the previous parts, but here it is again: Read More
Jul
28
Click here for Part 1. Click here for Part 2. In this part of our blog series on OSPF area types, our Area 11 is going to undergo a major flashback! The area is going to be reintroduced to an early 1980's American stereotype called Valley Girls and their Valspeak. The area is no longer going to be Stubby, but it is going to be like. . .like Totally Stubby! Lets review how we left Area 11 and how things looked when it was just a Stub area: Read More
Jul
26
Welcome back to our series on OSPF areas. Click here for Part 1 of the series. It is time to focus on normal areas and stub areas in this post. Recall our topology: Read More
Jul
25
Thanks to one of our brilliant CCIE R/S Written students, Nish, for his request of this series of INE blog posts. Nish is still struggling a bit with the different OSPF area types and how exactly they impact Link State Advertisements (LSAs). In this series, we will tackle each of the different OSPF areas in great detail, confirming our Level 1 knowledge at the command line as we progress. Here is the network we will use in this first post. Notice this simple network can be constructed easily in... Read More

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