This blog is not directly tied to any topics related to CCIE studies, but it can be useful. It’s more of a general networking post. I had fun researching this information and decided it would be a nice thing to share with experts such as our readers.

In the Packet Pushers Podcast episode 89 (OSPF vs IS-IS Smackdown – Where You Can Watch Their Eyes Reload) published few months ago, I made few statements about border routers in both OSPF and IS-IS and their differences. This prompted some disagreement on the panel consisting of Ivan Pepelnjak of NIL, Petr Lapukhov of Microsoft, host Greg Ferro and myself. In this post, I’ll examine OSPF issues and follow-up with IS-IS in the next.

For the purpose of this testing, I will use the network of three routers connected in a “chain”. I will not change this network layout, only the configuration of the routing protocols, as required. Even though both IOS and Juniper configurations are completed in production ProctorLabs racks, I gave routers fictional names to avoid slight router numbering differences between our Cisco and Juniper racks.

Lab time!
Read Full Entry »

OSPF virtual-links are a well-know subject to many CCIE candidates. One aspect of them seems to be troubling many students I talked to. That aspect is using OSPF virtual links in conjunction with “ip unnumbered” links. Let’s see what all the fuss is about.

Please note: This article is in a way an answer and the detailed explanation of the problem presented in the Interactive Troubleshooting Blog: OSPF Routing article posted on April 30, 2012.

Read Full Entry »

This is yet another post in our interactive troubleshooting series. I have a suspicion this one will be quite fun. Please, use the comments section of the post to post troubleshooting questions and I will update the post as we go on.

Read Full Entry »

Couple of days ago, I posted a small problem faced by one of our students and asked our readers to try and solve it. In this article, I will overview the possible solutions to that small puzzle. You should read the original “OSPF and BGP Puzzle” before we proceed. I’ll wait right here!
Read Full Entry »

I love interesting problems that we face when studying for our CCIEs. Especially fun are those that come from an unusual behavior of protocols.
Read Full Entry »