Understanding EIGRP – Part 3 (EIGRP Timers)

ccie r/s ccna r/s ccnp r/s Jan 09, 2017

Once of EIGRP’s claims to fame is its fast convergence in the event of a link failure. However, one thing that might slow down this convergence is timer configuration. That's the focus of this blog post, which is the third in a series of posts on Understanding EIGRP. If you missed the first couple of posts, you can get them here:

Let's beging our discussion of EIGRP timers by considering a situation where two EIGRP neighbors are directly connected to one another. If the physical link between them fails, each router’s connected interface goes down, and EIGRP can fail over to a backup path (that is, a feasible successor route). Such a situation is shown in the following figure:

 

Routers R1 and R2, shown in the above figure, are directly attached to one another. Therefore, if the cable between them physically breaks, each of the router interfaces connecting to that link go down, and EIGRP realizes that it...

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What is Cisco IWAN (Intelligent WAN)?

ccie r/s ccnp r/s Jan 05, 2017

One of the buzzwords you hear a lot in our industry these days is Cisco IWAN. But, what exactly is Cisco IWAN, and what can it do for us? That's what you'll learn in this video.

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Understanding EIGRP – Part 2

ccie r/s ccna r/s ccnp r/s Dec 02, 2016

In the first blog post in our Understanding EIGRP series, we were introduced to EIGRP’s features, in addition to a basic configuration example, and a collection of verification commands. Now, in this post, we’ll delve into the behind the scenes action of how EIGRP establishes a neighborship, learns a route to a network, determines what it considers to be the best route to that network, and attempts to inject that route into a router’s IP routing table.

EIGRP’s operations can be conceptually simplified into three basic steps:

Step 1. Neighbor Discovery: Through the exchange of Hello messages, EIGRP-speaking routers discover one another, compare parameters (for example, autonomous system numbers, K-values, and network addresses), and determine if they should form a neighborship.

Step 2. Topology Exchange: If neighboring EIGRP routers decide to form a neighborship, they exchange their full topology tables with each other. However, after the...

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Understanding EIGRP – Part 1

ccie r/s ccna r/s ccnp r/s Nov 18, 2016

I used to work as a Network Design Specialist at Walt Disney World, in Florida. Their massive network contained over 500 Cisco routers (and thousands of Cisco Catalyst switches). What was the routing protocol keeping all of these routers in agreement about available routes? It was Enhanced Interior Gateway Routing Protocol (EIGRP). That’s the focus of this blog post, which is the first of a series of posts focusing on EIGRP.

If you already have your CCNA R/S certification (or higher), you’re probably well acquainted with EIGRP. However, unless you have an eidetic memory (like Sheldon Cooper on The Big Bang Theory TV show), you probably don’t remember every single EIGRP command and concept. Therefore, this series of blog posts is going to review and reinforce those fundamental EIGRP concepts, and even introduce a few other fun facts.

EIGRP Fundamentals

There’s a long-running debate about the fundamental nature of EIGRP. At its essence, is EIGRP a link...

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Your Framework for Cisco Exam Preparation

You want to get your first (or next) Cisco certification, but do you have a specific preparation strategy, or are you just winging it? If you do have a structured framework you’re confidently executing against, congratulations! If not, allow me to share my seven-step framework for Cisco exam preparation.

Step #1: Identify Your Training Source

When it comes to learning what you need to learn, the good news is, you’ve got options. Let’s compare a few:

Cisco Learning Partner

The traditional approach, and the way I trained certification candidates for nearly fourteen years, is to take an official Cisco course from a Cisco Learning Partner (CLP). You might have the option of taking your course at a training facility or on-line, and you typically get access to the gear you need to perform lab tasks during the course. You also get Cisco’s official course material. However, a gotcha that many people don’t realize is that Cisco typically has different groups...

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BPDUGuard: A Spanning Tree Protocol Enhancement

ccie r/s ccna r/s ccnp r/s Aug 30, 2016

Yet another new topic on the new CCNA R/S v3 exam is BPDUGuard, which is an enhancement to Spanning Tree Protocol (STP) available on our Cisco Catalyst switches. Specifically, BPDUGuard can help prevent a Layer 2 topological loop by placing a port configured for PortFast into an Error-Disabled state if that port receives a Bridge Protocol Data Unit (BPDU).

This video demonstrates the operation of BPDUGuard, and then trains you on how to configure this simple yet powerful feature.

Kevin Wallace, CCIEx2 (R/S and Collaboration) #7945

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QoS Traffic Markings

One of the new topics on the new CCNA R/S v3 exam is Quality of Service (QoS). Having taught QoS for many years, I’ve noticed that one of the topics students find most challenging is QoS Traffic Markings.

This topic is all about how the binary math works behind the scenes to mark our traffic with specific levels of priority. So, to help demystify this topic, I created a new video (which is part of my upcoming CCNA R/S v3 Complete Video Course), and I wanted to share it with you. Enjoy!

Kevin Wallace, CCIEx2 (R/S and Collaboration) #7945

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2 of the Most Misunderstood QoS Topics

For me, the addition of QoS to the list of topic areas for the new CCNA R&S version 3 exam was a great thing. The reason is, QoS is my absolute favorite Cisco topic. So, I couldn’t wait to start recording the QoS portion of my CCNA R&S v3 Complete Video Course.

In fact, I recently shot this video on two of the most misunderstood QoS topics, Policing and Shaping. I thought this video could help you, whether you’re studying the Routing and Switching track or the Collaboration track. 

Kevin Wallace, CCIEx2 (R/S and Collaboration) #7945, CCSI 20061

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Configuring VRF-Lite

ccie r/s ccnp r/s Jun 07, 2016

You’re probably familiar with the concept of virtualization, where you can run multiple virtual servers on a single physical server. However, did you know that you can run multiple virtual routers inside a single physical router?

 

That’s possible with a really cool Cisco IOS feature called VRF-Lite. This video shows you how to perform a basic configuration of this exciting virtualization technology.

 

Kevin Wallace, CCIEx2 (R/S and Collaboration) #7945, CCSI 20061

If you enjoyed this article, you might also want to subscribe to my podcast:

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Multicast Routing on Cisco Routers

ccie r/s Apr 19, 2016

In this new video, you’ll get a simplified, yet comprehensive, look at multicast routing on Cisco routers. This video is appropriate if you work with multicasting in the real world or if you’re studying for your CCNA, CCNP, or CCIE Routing and Switching.

Some of the topics include:

  • The Benefit of Multicasting
  • IPv4 Multicast Addressing
  • IPv6 Multicast Addressing
  • Exercises: Constructing Multicast MAC Addresses
  • IGMP (versions 1, 2, and 3)
  • Reverse Path Forwarding (RPF) Check
  • PIM Dense Mode
  • PIM Sparse Mode
  • Live Demos (PIM-DM, PIM-SM, & Auto RP)

Enjoy the video!

Kevin Wallace, CCIEx2 (R/S and Collaboration) #7945, CCSI 20061

If you enjoyed this article, you might also want to subscribe to my podcast:

iTunes: http://kwtrain.com/podcast

RSS: http://kwtrain.com/rss

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