study re-think

I came to the realization after taking the demo that I should probably be changing how I’m studying for the CCDE. When I went for the CCIE I followed the path laid out from Cisco going CCNA -> CCNP -> CCIE and was satisfied with the preparation that this entailed. When I began in earnest to study for the CCIE lab I was much better prepared. Primarily in knowing exactly what I did not know and needed to concentrate on. I think the design track may be a better path for me to take in my pursuit of the CCDE – rather than proceeding directly to the CCDE written without getting the CCDP first. I’ve not taken the written exam yet, but plan to take the CCDP exam I need, 642-873, soon. What I’ve found so far is that the materials to prepare for 642-873 are just what I’ve been lacking. It goes into design topics at a more basic level than CCDE (obviously) but with enough detail to sate my appetite for network design that I’ve been looking for. The CCDP is a good certification to strive for, especially if you’re on the fence about how to study for the CCDE. Regardless, I recommend the CCDP as an end in itself, whether you want to pursue the DE or not.


CCDE Written Outline Topic 4 : CMIP and TMN

A few notes from the Written Outline Topic of Management:

“Identify when use of CMIP is appropriate”

CMIP stands for Common Management Information Protocol and was designed for OSI-based network management. It was designed as a competitor to SNMP and supports the following:

  • The ability to perform tasks – as opposed to SNMP which can only perform SET and GET
  • Logging and AAA
  • Better reporting of network conditions


“Identify when use of TMN is appropriate”

TMN stands for Telecommunications Management Network

I found this on Wikipedia : “TMN can be used in the management of ISDN, B-ISDN, ATM, and GSM networks. It is not as commonly used for purely packet-switched data networks.”

TMN uses CMIP.

From what I’ve been able to gather, TMN and CMIP are appropriate for GSM and circuit-switched networks. I don’t know of any implementations for packet-switched networks. Anyone care to disagree?

TMN Tutorial


CCDE presentation from Cisco Live 2008

I did not attend Cisco Live, but someone has posted the presentation Russ White gave on the CCDE here.

A few comments on the information in this presentation.

Under the “why are we doing this” section they note that a lot of L3 design issues are coming up, despite being “easy”. Expect a lot of L3 issues on the CCDE.

Business problems are the primary driver of the CCDE test questions.

The skill set tested should be timeless.

Is generally vendor neutral.

The practical will be computer-based – no lab environment.

You’ll be presented with a bunch of information, from which you generate requirements. After answering some questions through a variety of means, you’ll gain access to additional information.


CCO Documentation?

CCO contains a wealth of information for those preparing for the CCIE exam. Unfortunately, that same information is not necessarily good preparation for the CCDE exam. The CCDE won’t be testing your CLI skills, or even your Cisco feature implementation skills. No, the CCDE claims to test timeless network design skills, which requires something different. Design is considered a dark art, since most of the answers begin with ‘it depends’. The trouble is, you’re expected to know what the conditions for deployment will be, and as network designers we work with imperfect information. Customer requirements are fuzzy since customers sometimes don’t know what they want. Feature parity between platforms can be frustrating. The CCDE will most likely be testing your ability to see big-picture issues instead of digging into the weeds. Nobody but the CCDE creators know, of course, but we can infer this information by the reading list and written outline.

Let’s look at the first topic: IP routing

  1. Explain route aggregation concepts and techniques.
    1. Purpose of route aggregation
    2. Scalability and fault isolation
    3. How to Aggregate

Nothing in here will be specific to Cisco products. Nothing in here will be feature/platform dependent. What is in here, however, is IP routing protocol dependent.

What is the purpose of route aggregation?

We aggregate to scale our networks. By aggregating, we reduce the impact of a link flap in one area of the network. We hide topology through aggregation. Link-state and Distance-vector routing protocols aggregate in different ways. If we want to hide topology in link-state, we need to use areas for aggregation. Distance-vector by definition hides topology.

Do you notice what’s left unsaid in the above question? I think a key question you need to ask yourself is:

What are the problems with route aggregation?

Route aggregation hides topology. Route aggregation can result in suboptimal routing. How do you fix these issues if you need to? Why should you care? Topological information hiding can be useful, but can be detrimental in the case of Traffic Engineering and Mobility. With Mobility, as your users move around the network you will be unable to aggregate as effectively. Suboptimal routing is something you may not care about immediately, but it could cause problems for your customers depending on link speed, etc, and you should know how to address these issues in your design.


back home..

Hi everyone, I’m finally back home after a week without Internet access. I’ve received a lot of comments & emails that deserve replies and/or posts. I’ll be working to address these issues shortly. Bear with me please as I recover from jetlag.