Posts from ‘CCDE’
Holy Bootcamps Batman!
Are you wondering what the month of August 2010 will bring for INE fans?
Try all new, online bootcamps in the following disciplines:
- MPLS
- BGP
- CCNA
- CCNP
- CCDA
Watch the blog and your email for all of the exciting new details.
Join the INE Experts Online in August
This goal of this post is breif discussion of main factors controlling fast convergence in OSPF-based networks. Network convergence is a term that is sometimes used under various interpretations. Before we discuss the optimization procedures for OSPF, we define network convergence as the process of synchronizing network forwarding tables after a topology change. Network is said to be converged when none of forwarding tables are changing for “some reasonable” amount of time. This “some” amount of time could be defined as some interval, based on the expected maximum time to stabilize after a single topology change. Network convergence based on native IGP mechanisms is also known as network restoration, since it heals the lost connections. Network mechanisms for traffic protection such as ECMP, MPLS FRR or IP FRR offering different approach to failure handling are outside the scope of this article. We are further taking multicast routing fast recovery out of the scope as well, even though this process is tied to IGP re-convergence.
It is interesting to notice that IGP-based “restoration” techniques have one (more or less) important problem. During the time of re-convergence, temporary micro-loops may exist in the topology due to inconsistency of FIB (forwarding) tables of different routers. This behavior is fundamental to link-state algorithms, as routers closer to failure tend to update their forwarding database before the other routers. The only popular routing protocol that lacks this property is EIGRP, which is loop-free at any moment during re-convergence, thanks to the explicit termination of the diffusing computations. For the link state-protocols, there are some enhancements to the FIB update procedures that allow avoiding such micro-loops with link-state routing, described in the document [ORDERED-FIB].
Even though we are mainly concerned with OSPF, ISIS will be mentioned in the discussion as well. It should be noted that compared to IS-IS, OSPF provides less “knobs” for convergence optimization. The main reason is probably the fact that ISIS is being developed and supported by a separate team of developers, more geared towards the ISPs where fast convergence is a critical competitive factor. The common optimization principles, however, are the same for both protocols, and during the conversation will point out at the features that OSPF lacks while IS-IS has for tuning. Finally, we start our discussion with a formula, which is further explained in the text:
Convergence = Failure_Detection_Time + Event_Propagation_Time + SPF_Run_Time + RIB_FIB_Update_Time
The formula reflects the fact that convergence time for a link-state protocol is sum of the following components:
- Time to detect the network failure, e.g. interface down condition.
- Time to propagate the event, i.e. flood the LSA across the topology.
- Time to perform SPF calculations on all routers upon reception of the new information.
- Time to update the forwarding tables for all routers in the area.
Tags: CCDE, ccie, fast convergence, ospf, sub-second convergence, timer tuning
As my 4-year recertification timeline was about to lapse, I had to go and pay $350 to recertify 
There was no other challenge, as I picked CCDE written for recertification, keeping in mind to take the practical test again this year. To my greatest surprise, the exam was almost the same it was in September 2007, when I took the beta version. Just this time the number of questions was 100 not 170 and they give you chance to review and navigate among the questions (just like it was in old CCIE Written). Apparently, the CCDE written test engine has never been updated the way that CCIE R&S Written was, with the new scoring model based on 1000 points. Since 2007 I spent considerable amount of time studying (back then I went unprepared, but still passed with 70 point) so the exam went disappointedly easy, as I haven’t seen anything new that I didnt see in 2007. As usual, the main focus is on IP Routing with the addition of Tunneling techniques (MPLS, GRE, IPSec) along with QoS, Network Management and Network Security. You may find the very detailed blueprint here (though formatting is broken in a number of places):
http://www.cisco.com/web/learning/le3/ccde/ccde_exam_information.html
The books I found most helpful to prepare were:
- Definitive MPLS Network Designs
- BGP Design and Implementation
- IS-IS: Deployment in IP Networks
- OSPF: Anatomy of an Internet Routing Protocol
- Optimum Routing Designs (you may mainly concentrate on IGP protocols and refer to the book above for BGP)
- EIGRP for IP: Basic Operation and Configuration
- Cisco IP Routing by Alex Zinin (for you hardcore routing fans)
- OSPF and ISIS: Choosing and IGP for Large Scale Network
- Layer 2 VPN Architectures
- Interconnections, 2nd edition: Bridges, Routers, Switches and Internetworking Protocols. (Just for fun reading and a lot of background information)
Lastly, anyone preparing for the CCDE certification – even though the written test is easy, do not take it lightly as you’ll need all the knowledge during the practical test. There are other challenges in the practical exam, but hopefully the plan I developed to deal with that will work for me – we’ll see 
Tags: CCDE, ccde blueprint, ccde written, recommended reading, vue
It is with great pride that we announce our esteemed colleague and friend, Scott Morris, quad-CCIE, has passed the Cisco Certified Design Expert (CCDE) exam. Scott joins a select few in the world to have passed this daunting certification. It seems like just yesterday (1998), when Scott passed the Cisco Design Specialist certification.
Please help us DoS attack the comments area of this site to help congratulate Scott!
CCDE #20090013
Scott Morris (left) and Keith Barker in a pre-celebration at Ice Lounge (Las Vegas, USA)
The Beta Test is over! Check out W-INE Radio at:
http://radio.ine.com:8000/listen.m3u
The station features Tech Talks and other fun, educational sessions, as well as CD quality tunes to study by!
The Podcast of our Core Knowledge Section Tech Talk is available at:
http://www.ine.com/podcasts/ckp1.mp3
Do you have programming suggestions? Just e-mail wineradio@ine.com
Our blog site continues to skyrocket in viewers and active participants. Thank you so much for supporting this site and reading and commenting on what we have to say. We love to teach and WRITE, and without your support, the blog WRITING part would certainly be wasted. ☺
One of the things I keep noticing about our blog is Cisco questions pretty unrelated to a particular blog in the comments for a certain post. I wanted to take this opportunity to remind all of our readers about a powerful resource on our site for any questions you might have. It is our Online Community at http://ieoc.com.
February 11, 2009: CCDE Practical Exam
Have you passed your CCDE written exam? Individuals that have completed the written portion of the CCDE exam can register immediately to take the practical portion of the exam. The next CCDE practical exam is scheduled for Wednesday, February 11, 2009, in Chicago, Illinois, US and London, UK. The cost of the exam is $1,400USD. Candidates must have passed the CCDE qualification exam prior to registration.
In this post I will try to summarize the things known so far about the CCDE written/practical exams and provide some (hopefully) useful tips and hint. Even though I didn’t receive my exam results yet, I think it’s still a good idea. At least, I’m still the person who “tried” and haven’t “failed” yet (at least unaware of that
The first question that people ask – would getting CCDA and CCDP help in achieving CCDE? That would help, a little. Most useful thing would be summarization your knowledge of IP Routing protocols and QoS topics. Plus, you can find some useful things in the new ARCH2 training course. However, I don’t think it is necessary to become a CCDP in order to get enough knowledge for taking CCDE.
Quote from Cisco:
Practical Exam Release for New CCDE Certification
Cisco is now formally announcing the availability of the CCDE practical exam. The exam is currently scheduled to take place on February 11, 2009 in Chicago and London. CCDE, on par with the award winning CCIE certification, recognizes the growing number of networking experts who have in-depth infrastructure design knowledge, which enables them to assess network business requirements. Candidates can access CCDE blueprints and a list of recommended training materials on the CCDE web page.
Well, I figure it’s my turn to write something about the CCDE exam that, as Brian M. noted, he, Petr and I suffered through…. errrr… took yesterday!
It was… ummm… a long day! Definitely be prepared to sit and digest information as you go through. The catchy part is that there is not a whole lot of information out there on the concept of the CCDE Practical. Well, with it still being a beta and all. If you managed to catch the Networkers presentation from Orlando, that’s a good bit of information.
If you worked with the online Demo of the exam (link in Petr’s blog) than you have some clue on the format there. It will be interesting to see what all comes out of the beta in terms of scores and pass/fail results. It was NOT an easy exam by any stretch of the imagination! Hats off to Russ, Bruce, Bill, Steve, Sarah, Theresa and the myriad of other folks involved in the program’s inception.
Were there glitches yesterday during delivery? Sure. It’s a beta. It’s Adobe Flash, which isn’t exactly the most stable thing in the world, and some interesting creation tools to go with it. Some people had other hardware problems (which the folks from Pearson/Vue were wonderful about fixing IMHO). But there were plenty of people from both Pearson/Vue and Cisco around at each of the testing centers to log, evaluate and resolve (if possible) anything we ran into.
Now, like Petr pointed out, those who may be used to sitting for 8′ish hours for a CCIE lab, you still have a big difference between that exam and this one! In the CCIE lab, you often wonder where time goes because you are busy typing, configuring, verifying (you DO do that, right?) and possibly troubleshooting. The point is you are active the entire time.
At this exam, there’s reading to do. Then there’s questions. Then there’s staring back at the reading or your notes or your pre-conceived thoughts on the “customer” that has whatever issue you are presented with. And there’s staring back at those “documents” coming up with some answer to the question. And after several hours of this, you are looking around for a white-hot poker to possibly stick in your eye. I’m happy to report that there were no confirmed maimings at the event!
Design, as you know, is an incredibly subjective concept! Sometimes there are definite right/wrong answers. Sometimes there are many flavors of right-ish answers. This exam is a lot about thought-process, which is really quite interesting but difficult to convey in a short period of time.
There were almost 50 very well-known folks throughout the industry spread across two of Pearson/Vue’s testing centers in downtown Chicago yesterday. And then there were many of us who went to a wonderful reception that Cisco sponsored afterwards! Kind of a celebration/commiseration drinking opportunity! (grin)
Then, of course, there’s bar-hopping afterwards. But why should this have been different than any other gathering of network engineers! No, seriously, it was good to see many of the people there and the caliber of the people involved in this beta. Cisco is doing quite a bit to assure the success of the program, and I think that was evident throughout the evening.
No matter what the final scores happen to be (although I had decided there was a 20-point bonus per “major error” spotted (major being very subjective, because the world did not end with any of them!) and therefore I have at least 60 points!), I think it will give the folks on the team plenty of opportunities to look at this and evaluate how this assessment actually went.
There were opinions all over the place being shared at the party. Some good, some not as good. Some believing they had the right answer and the CCDE exam went a different way (did I mention there’s no “back” button?). But that’s to be expected. Isn’t part of being a successful networking engineer revolve around the “fact” that you are right all the time?
It was a long day. I was proud of myself for not falling asleep in the afternoon! Although I thought that pillows should have been provided for that! But now the difficult part comes: WAITING. Our “score reports” were basically “Thank you for playing” notes, similar to any beta, that the results would be released soemtime in the future.
So now comes the HARD work on Cisco’s part! Cisco has to grade them. As long as I don’t get 0, I’ll be happy! And Brian M. will be happy as long as he score 1 more point than I do! All in all, it was a very interesting day!
Loading ...
