Orhan Ergun No Comments

OSPF Multi-Area Adjacency | OSPF Area Placement | RFC 5185

OSPFv2 by default setup only one adjacency over a single link. But this can be an issue some time and as a network designer you should understand the consequences and know the available solutions.

Placing a link in wrong OSPF area can create an OSPF sub optimal routing especially in hub and spoke topology.

In IS-IS or OSPFv3, this wouldn’t be an issue because IS-IS and OSPFv3 allow link to be placed in more than area or level. (In IS-IS, area is assigned to the router, not to the link. Thus I use level keyword)

Let’s look at the below network to understand what is the issue and how OSPF multi-area adjacency can solve the sub optimal routing problem. Read more

Orhan Ergun No Comments

More network design resources are available for subscribers !

As a reader of this blog, you can access all of the posts on the website for free. But if you don’t know yet, this website has a membership area.

When you become a member you get access to 50+ hours network design videos which will help you in Cisco CCDE exam as well as real-life network design. There are technology mind maps, design quizzes, design e-books and technology comparison charts.

Imagine that you have to select a technology for a particular design but you don’t know all the available tools. Comparison charts will teach you the pros and cons of each technology, protocol and where to use them in a network design.

Below resources have been recently added to the members area of www.orhanergun.net


Mind maps will help you to study technologies as well as will be quick refresher from the design point of view. More mind maps will be added shortly, stay tuned.

IPv6 Mind Map
QoS Mind Map
Multicast Mind Map
VPN Mind Map
General Design Mind Map
BGP Mind Map
GETVPN and BFD Mind Maps


Comparison Charts

New comparison charts as below.

OSPFv2 vs OSPFv3
MPLS QoS- Uniform vs Short Pipe vs Long Pipe
BGP Route Reflector vs Confederation
PIM ASM vs SSM vs Bidir



You will find questions and answers of the below quizzes in the membership area.

IPv6 Design Quiz
OSPF Design Quiz
CCDE Demo Scenario : This is similar to CCDE Practical exam. 2 hours long demo scenario.You should test yourself to see whether you are ready for CCDE Practical as soon as possible.

If you are not a subscriber yet, you can start today your membership !


If you have any question regarding subscription send an email to orhan@orhanergun.net

Orhan Ergun No Comments

50 000 Page views of orhanergun.net between March-May 2015

This blog received 50 000 page views between 1 of March and 1 th of May.I shared you couple more metrics from the site stats in addition to Pageviews.

Since at the same time two classes I teach ( Pre-CCDE and CCDE ) in addition to my other jobs, I couldn’t update the blog since a month too much. But still very good numbers and I thank all of you.


orhanergun.net statistics


A picture is worth a thousand words.

Orhan Ergun 39 Comments

ASK your questions and SHARE your opinion

I receive lots of questions from my students, readers, customers, followers on network design.

I try to  answer as quickly as possible and in detail.

Thanks to all of them ! I receive a lot of kind emails, messages from them to put my effort on this blog as well.

But for many reasons, I have created this category.

  • Those questions and answer can be beneficial to many other people if I post them here.
  • It is hard anymore to reply every email individually, at least timely manner.
  • When I share a post on social media, I receive a lot of feedback and have a good conversations there. Please share them here as well 🙂

Thus, please ask your questions, give your suggestions for the questions, share your opinion for the blog,recommend new blog categories,

So do you like this blog ? Share in the comment box below if you liked 


Orhan Ergun 6 Comments

Do you really need Network Training ?

Certification is cool, opens the door to new companies, positions , maybe to the better roles,you can proud that you have CCIE, JNCIE and so on.

Cisco , Juniper , HP, every major companies have certification program and network training is a big business. We all know that !

Have you ever asked yourself, Do you really need Network training ?

Read more