Archive for February, 2010


In this post, we will examine the Control Plane and for Forwarding Plane components in more detail and discuss their interaction. This post will reference the following diagram:

mpls arch

Let us start at the top of this illustration and work our way down, reviewing these components and focusing on their interaction.

First, notice the Routing Protocol is responsible for building the IP Routing Table ( or Routing Information Base RIB). This used to be our only real concern for this lab! (Ahh, the good ole’ days.) For your current lab exam, this is where we configure or repair OSPF, RIP version 2, EIGRP, or BGP.

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Please join us in the following Live Open Lectures this week!

Tuesday, March 2, 2PM EST US – TCP Intercept Explored

Thursday, March 4, 2PM EST US – Troubleshooting Layer 2 – Catalysts

There was a problem with the recording of Troubleshooting Layer 2 – Catalysts last week, thus the “mulligan”.

Enjoy the lectures everyone and we cannot wait to “see you” in class!

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In the last blog post, we discussed key mechanisms found in the MPLS Forwarding Plane. In this post, we are going to examine a key element of the Control Plane – LDP (Label Distribution Protocol).

The MPLS Architecture

The MPLS Architecture

We remember from the previous discussions that the Forwarding Equivalence Class (FEC) represents the path that packets are going to take through the MPLS cloud based on a criteria like the iBGP next-hop address (in the common case of L3 MPLS VPNs). Data moves efficiently through the MPLS tunnel thanks to the label swapping behavior of the MPLS devices. But how are these labels distributed and maintained throughout the MPLS cloud?

Well, an administrator could certainly “hand pick and assign” the labels, but this would only be in an environment where the admin is paid by the hour! ;-) It is obvious that a dynamic process is needed. There are three dynamic options that are used today:

  • Label Distribution Protocol (LDP)
  • Resource Reservation Protocol (RSVP)
  • Border Gateway Protocol (BGP)

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We need to move this Lab Meet-Up to run sooner than originally announced.

The new date and time is:

Wednesday, March 3 at 2 PM EST US

If you cannot attend, remember to send your questions about the lab to so that we can cover them in class. Also, this will enter you in the class drawing for 100 Graded Labs Rack Rental Tokens! Woo-hoo!!!!!!

OK, OK, I know what you are thinking – I never win raffles either, but you definitely cannot win if you do not play.


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Well I sat for my v4 R&S lab and just got the core report back. I am very sad to say I was close, but didn’t make it over the bar. Here is my feedback and preparation strategy.

First – I used INE workbook volume 1 through 4. Whatever you do, don’t make the assumption that you should skip the volume 1 because it is too basic. I will tell you first hand, it is critical to work through volume 1. Not only will it help you adapt new methods for dealing with specific technologies, but it will also help you out when it comes time answer those pesky core knowledge questions at the beginning of your lab! Some people may be fine just reading lots of books but personally, I learn better by doing a little bit of readying and the applying the knowledge using a hands-on approach. Also ally the video on demands that INE has to offer. You can pause it during certain topics you wish to lab it up on. Then, watch it over to see if you did it right.

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Hello everyone!

I am updating Practice Exam 2 (In Progress) for the CCIE Written Exam Bootcamp in your Members’s Site. I will be adding questions over the next couple of weeks. Currently, you will find some new Multicast Addressing/IGMP/MLD questions in there for your entertainment.

I am focusing on Practice Exam 2 right now for two main reasons. 1) It is allowing me to address some deficiencies with Practice Exam 1 and the lectures, and 2) More and more students are using this bootcamp as a prep tool for the dreaded Core Knowledge section.

Let us examine one of the new questions and walk through my solution logic.

Q. How does a router respond after receiving an IGMP Leave Group message?

a. The router does nothing

b. The router responds with a Membership Report

c. The router responds with a Group Specific Query

d. The router responds with a General Query

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Over time I was thinking of putting together the two blog posts made in the past about MSTP and adding more clarification for MSTP multi-region section. This new blog post recaps the information posted previously and provides more details this time. Additionally, it discusses some MSTP design-related questions. Both single-region and multiple-region MSTP configurations are reviewed in the post. The reader is assumed to have good understanding of classic STP and RSTP protocols as well as Cisco’s PVST/PVST+ implementations.

Table of Contents

Due to the large size of the document, a table of contents is provided for the ease of navigation.

Historical Review
Logical and Physical Topologies
Implementing MSTP
Caveats in MSTP Design
MSTP Single-Region Configuration Example
Common and Internal Spanning Tree (CIST)
Common Spanning Tree (CST)
Mapping MSTI’s to CIST
MSTP Multi Region Design Considerations
Interoperating with PVST+
Scenario 1: CIST Root and CIST Regional Root
Scenario 2: MSTIs and the Master Port
Scenario 3: PVST+ and MSTP Interoperation
Further Reading

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The MPLS Architecture is divided between the Control Plane and the Data or Forwarding Plane. In this blog post we will focus on components and processes critical to the operation of the Forwarding Plane.

The MPLS Architecture

Fig 1. The MPLS Architecture

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A key to the success of MPLS and the L3 MPLS VPN is the use of “tunnels” created by the MPLS labeling. Tunnelling in the service provider cloud has many benefits:

  • Only edge points (ingress and egress) need to understand the meaning of the inner network information (prefixes); core routers simply switch traffic based on labels
  • You can easily re-direct tunnel traffic explicitely
  • Tunnels can be created within tunnels
  • The tunnel is less prone to data spoofing
  • The overhead with MPLS is relatively low (4 bytes per MPLS header)

Examine the Exhibit as we review some of the additional, key components of the L3 MPLS VPN:mpls components

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Friday, March 5, 2 PM EST US

Join our instructors in the Lab Meet-Up for Lab 4 of Volume 2 for the Version 4.0 exam.

You should not miss the valuable technology and strategy insights shared in this session using Lab 4 as a backdrop.

In this session, we will be giving away 100 Graded Labs Rack Rental Tokens for one lucky individual that submits a question about the lab via the live chat or email. Email your questions to

Like Open Lectures, these sessions tend not to run over 2 hours in length. And also like Open Lectures, they are made available for On-Demand viewing immediately following the event.


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