A few days ago, there were a couple of tweets in my stream about RIP. Yes, the much-maligned, older-than-the-hills Routing Information Protocol. These particular tweets came from a couple of people that are in the study process for their CCIE lab exam. Having had a couple of shots at the lab myself, I found it prudent to mention that while RIP was indeed on the exam, don’t believe for one second that it’s going to be easy. While I can’t and won’t discuss specifics about what I’ve seen, I think I can speak with generality about why RIP is still very much a topic on the now version 4 of the venerable CCIE exam.
Every entry-level networking student learns about RIP. It was the very first routing protocol, and as such serves as a prototype for beginners to learn about topics like hop counts, routing tables, and other more esoteric subjects. RIP was designed to do one thing and do it well. Because of that, it doesn’t take long before he complexity of RIP is exhausted and students move on to bigger and better routing topics. In fact, the only purpose that RIP serves past the very early point is as a yardstick, a way of measuring how much better something is at its job than RIP. Students quickly learn why EIGRP is much better as an advanced distance vector routing protocol. Or why link-state is much better for larger networks. Because of this, CCNAs and JNCIAs all over quickly develop the idea that “RIP sucks”.
I’m not a RIP apologist by any stretch of the imagination. But I also have a healthy respect for the fact that while RIP may not be the most impressive routing protocol by today’s lofty standards, its place in history is secure by it’s longevity and due to the fact that we wouldn’t have EIGRP and OSPF today if RIP hadn’t paved the way for them. So, why then would a 22-year old protocol that has been eclipsed in almost every conceivable way still show up in the blueprint for the granddaddy of all routing and switching exams? In short, to screw with your head.
Anyone with a driver’s license can probably cite traffic laws. And any of them can’t most likely describe the procedure to parallel park. Or park on a hill. But the second half of the US drivers test doesn’t quiz you on your knowledge of how to parallel park. They make you go out and do it. And often, you don’t get to parallel park in perfect conditions like you practiced for weeks and months before your test. No, if the driving instructor is particularly insidious, they might make you parallel park on a hill in a school zone. In much the same way, RIP is on the test to mess with you. You know RIP inside and out. If you’ve read Jeff Doyle’s Routing TCP/IP volume 1 you can likely diagram a RIP update packet with some toothpicks and a pencil. But, the devious-minded proctors and test writers aren’t going to ask you CCNA-level RIP questions. No, much like the driving instructor, they are going to make you apply your RIP knowledge to situations you might not have encountered in practice. Like establishing RIP neighbor relationships across 4 routers with no tunnels allowed. Or, more likely, they will give you a very simple setup followed by the most infamous of all CCIE candidate 4-letter words: redistribution. Most people know how RIP ticks, but when you start injecting RIP into a perfectly stable OSPF topology, that’s when the rubber hits the road and most things start falling apart. Knowing how to pick up the pieces after RIP trashes your orderly link-state protocol is one of the things that shows you are a RIP genius and aren’t scared to get your hands dirty.
You might ask yourself, “Well, anyone can write evil RIP questions all day long. Why is it still on the exam. Who even still uses RIP?” Good question? Who still uses frame relay? Or dial up modems? Or bridges? Being a CCIE means that you aren’t phased when you run into something old and (relatively) complicated. It means you understand why RIP and frame relay and bridges paid their dues so that today we could have OSPF and MPLS and TrILL. And as long as there is still a mainframe out there that only speaks routed or a network that has two routers that were made during the Carter administration, you are still going to encounter RIP. And if you think outside the box on that stressful day in a dark lab somewhere, you don’t have to worry about being RIPed off by your grandfather’s routing protocol.