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...

Continue Reading...

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.

Continue Reading...

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...

Continue Reading...

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...

Continue Reading...

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...

Continue Reading...

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

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

iTunes: http://kwtrain.com/podcast

RSS: http://kwtrain.com/rss

Continue Reading...

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:

iTunes: http://kwtrain.com/podcast

RSS: http://kwtrain.com/rss

Continue Reading...

Fundamentals of VRF-Lite

ccie r/s ccnp r/s Feb 24, 2016

Have you ever used some sort of virtualization software (e.g. vmware) to get multiple virtualized servers running on a single physical server? It’s a great way to save resources, by eliminating the need for extra physical servers. Well, similar to how we can virtualize multiple servers on a single physical server, we can virtualize multiple routers on a single physical router.

Each of these virtual routers can have their own independent IP routing table and are logically isolated from the other virtual routers residing in the same physical router. This can offer a solution to service providers wanting to keep their customers’ network traffic (including the IP routing tables of customers’ routers) isolated from one another. Or, in a large enterprise, perhaps you have a design requirement to segregate different applications (e.g. voice, video, and data).

One solution Cisco offers to make this router virtualization possible is called VRF-Lite. Some literature...

Continue Reading...

Cisco Learning Labs – Review

ccna r/s ccnp r/s Jan 12, 2016

How do you get hands-on experience when you’re preparing for your CCNA R/S or CCNP R/S certifications? One option is using the Cisco Learning Labs. You can check out my review here.

Links to Purchase Cisco Learning Labs:

ICND1: http://kwtrain.com/icnd1labs

ICND2: http://kwtrain.com/icnd2labs

ROUTE: http://kwtrain.com/routelabs

SWITCH: http://kwtrain.com/switchlabs

TSHOOT: http://kwtrain.com/tshootlabs

Kevin Wallace, CCIEx2 (Collab. & R/S) #7945

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

iTunes: http://kwtrain.com/podcast

RSS: http://kwtrain.com/rss

Continue Reading...

Troubleshooting Route Redistribution

ccie r/s ccnp r/s May 15, 2015

This video shows you how to troubleshoot a route redistribution scenario with multiple redistribution points.

This video is a sample from my new CCNP R/S v2 Complete Video Course Library (which includes the ROUTE, SWITCH, and TSHOOT Complete Video Courses ), and it’s available for preorder HERE.

Also, be sure to check out my other Complete Video Courses:

CCNA Complete Video Course

ROUTE Complete Video Course

SWITCH Complete Video Course

TSHOOT Complete Video Course

Enjoy your studies!

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

Continue Reading...
Close

50% Complete

Two Step

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.