A couple of days ago I passed the Cisco Certified Design Expert (CCDE) Qualification Exam which means that I am now eligible to take the CCDE practical. I’m aiming to give that a try in May. This post will give some insight into what a candidate needs to pass the CCDE Qualification exam and how to study for it.
The CCDE is a very broad exam. The ideal candidate must have a very strong background in Routing & Switching (RS) and Service Provider (SP) technologies. These are the meat of the exam. It is also desirable to have a decent knowledge of Data Center (DC) and security technologies. It’s also desirable to have a basic understanding of wireless and storage technologies.
It’s difficult to study for the CCDE and the CCDE Qualification Exam if you don’t have enough experience in the real world. While a person can study for the CCIE without a lot of experience, doing the same for the CCDE is difficult because design and network architecture requires implementation experience and design experience. The ideal candidate should be CCIE RS and SP certified already or have the equivalent knowledge of someone that is. Does that mean that it’s impossible to pursue the CCDE without them? No, but it will be very very difficult. There are a few non CCIE’s that have succeeded but they are the exception to the rule.
Make no mistake, this is a design exam but it still requires deep technical knowledge. The difference is that you use that knowledge to make design decisions instead of what commands to type. You don’t need to know any commands but you do need to know how to use the same AS at all customer sites in a MPLS VPN. See where I’m going? While you don’t need to type the allowas-in or as-override command, if you don’t know that they exist, you won’t know how to design a MPLS VPN where each customer site uses the same AS.
The CCDE exam will likely not ask you questions what the EIGRP header looks like but you need to know what a Query is and how you can do Query scoping with filtering and summarization. This means that studying for the CCDE is different than the CCIE but you can’t just skim through technologies. You need to understand how they work to understand how to design networks with these technologies. Don’t go too deep into technologies, you won’t be able to cover the breadth of the CCDE and the CCDE Qualification Exam if you do, but don’t think that you don’t need to understand the technologies either.
The CCDE is all about knowing concepts like fate sharing, network virtualization, flooding domains, fault domains, summarization, IGP and BGP design. It’s a control plane based exam which means that the focus is on L3 technologies but you must understand L2 and its implications as well. You must understand how a link state protocol works by building a Link State Data Base (LSDB) and running Shortest Path First (SPF) to calculate the best paths. You must understand what triggers a partial or full SPF run. You must understand how placing your flooding boundaries may affect the scalability of the network. You must be very comfortable with anything relating to IGP or BGP. How will implementing route reflectors affect your traffic going out of your AS? Since a RR reflects the paths with the IGP cost based on its own point of view, suboptimal forwarding is likely when using RRs. What can you do to prevent this? Put an RR in every Point of Presence (PoP)? You could, but it’s not very scalable… What about Add Path? Absolutely, but it requires support on both the RR and the clients. How many paths should you reflect?
What kind of resources should be used to study for the exam? Thankfully Elaine Lopes and her team has put together an expanded blueprint which is available CCDE Written 2.0 Expanded Blueprint here. Please note that there are two versions available depending if you are taking Written 2.0 (before July 26 2016) or Written 2.1 (after July 26). The new version contains some SDN/NFV topics which are being included in all the expert level exams. I recommend that you grade yourself on your knowledge before studying. Be honest, if you don’t admit your weakness now, it will show in the exam later. Cover all the topics that are included in the blueprint. Some of the essential books are “Optimal Routing Design”, “CCDE Study Guide” and “CCDP ARCH” book. The CCDE Study Guide book is geared towards the practical exam but can be a good resource for the written as well. I recommend that you get a Safari Books account to get access to the books needed to study for the exam. The other resource that you must tap into is the Cisco Live presentations. Look into sessions such as “OSPF Deployment in Modern Networks”, “ISIS Deployment in Modern Networks”, “Scaling BGP” and any session relating to design. It’s very useful to study topics such as DMVPN and GET VPN. I prefer the PDFs but there are videos available as well.
The CCDE and the CCDE Qualification Exam is a lot about thinking about design and discussing with your peers. If possible, find someone that is also studying for the exam and start discussing design with them. Based on our different backgrounds we can have very different input into the design process and you will learn a lot when discussing and listening to other engineers.
The CCDE and the CCDE Qualification exam is a very tough exam, don’t understimate it. You should already be an expert in implementation or have a very strong background in network design. To anyone pursuing this exam, good luck in your studies!