Virtualization is a vital concept in networking. As technology continues to advance, knowledge about what it takes to virtualize a network is crucial.
Virtualization is the practice of using software to simulate traditional hardware platforms and create virtual software-based systems. Network virtualization enables professionals to create a single virtual network or partition a physical network into multiple virtual networks.
Network practitioners studying to become Cisco Certified Network Professionals (CCNPs) or Cisco Certified Internetwork Experts (CCIEs) should be adept on all things virtualization. One trend driving virtualization is the emergence of cloud networking, as service providers increasingly use virtualization to deliver services to enterprises.
"Expanding your horizon of knowledge to all these players that are now involved in virtualization" is important for aspiring network pros to understand, said Patrick Gargano, content engineer at Cisco and author of 31 Days Before Your CCNP and CCIE Enterprise Core Exam from Pearson. In the chapter "Day 7" from his book, Gargano defines virtualization concepts and outlines topics found on the exams.
In this Q&A, Gargano discusses the importance of network virtualization and offers advice on how CCNP and CCIE test takers can prepare for their exams.
Why is virtualization important in networking?
Patrick Gargano: When we think of virtualization, we often think of the companies that started in that space. What they were doing was virtualizing machines. They were virtualizing PCs, virtualizing resources, so they could maximize the physical resources they had on a data center. instead of having 100 PCs, they would have a really powerful server that was running those 100 PCs.
What Cisco is doing in virtualization is virtualizing the hardware: routers, switches, access points and firewalls. The list goes on and on. Almost every time we come up with a new physical product you can actually put your hands on and play with, there's a virtual version of it that comes along not too long after.
What's driving this is what's happening in the cloud. Players like Amazon, Microsoft Azure and Google Cloud offer these incredibly powerful infrastructures we want to share and leverage. One of the ways of doing it is by deploying virtual machines or virtual resources.
In the good old days, you'd have a data center. You own your data center, you own your stuff and all your data was on your gear. Now, all your stuff is in the cloud. It's owned and operated by Microsoft or Amazon or Google. And you're using their equipment and storing all your data on there. Again, all the virtualization is happening there, so they can share that resource with thousands of clients.
What should aspiring CCNPs and CCIEs know about virtualization?
Gargano: These are like two different conversations. If I'm talking to someone about their career and what they need to know for their career, that's one angle. If it's someone who's planning on sitting [for] an exam and passing that exam to further their career, there's some very specific [concepts they need to know]. When Cisco comes out with an exam, they come out with an exam blueprint, which has a list of all the topics that exam covers.
It depends if we're having a conversation in terms of your general career and what kind of virtualization knowledge you should have. If that's the case, then it comes back to my first answer, which is expanding your horizon of knowledge to all these players that are now involved in virtualization.
If you look at the exam blueprint, they're specifically looking at things that can be deployed in your own network, which can be virtualized. I think they deal with it a little bit in the CCNA [Cisco Certified Network Associate] exam. At the CCNP level, it's about how virtualization is performed on a piece of hardware, like different types of VMs. But that's specific to an exam.
For specific exams, and in terms of virtualization, it's a narrow area. It's really about a physical solution or a virtual solution deploying [on] the network. It can also go down to the point where a student has to know certain commands to activate these features.
What are some other use cases for VMs?
Gargano: One of the classic ones, and the cheapest example, is being able to simplify the infrastructure companies have. If you go back 10, 25 years and you look at what people needed to buy to be able to run their business, [they needed] multiple servers, and each server had one job. You bought this $10,000 piece of gear, and it did this one thing really well. It took up all this room in your rack and used up all this power, but it just did this one thing. Now, you buy this one piece of gear, and it's doing 50 things. It [spins] up all these different VMs for databases, for security, you name it.
How does virtual routing and forwarding (VRF) aid the virtualization process?
Gargano: [If you] have a router, you can use some Cisco commands on that router to cut it up, break it up into smaller virtual routers, and that's what the VRFs are. When you create VRFs -- let's say we call it VRF Blue and VRF Red -- what you've done is created two little routers that are isolated from each other. Whatever happens in [the Blue] router, the Red one has no impact. It's completely isolated from the Blue one. This technology is super popular with service providers.
Let's say you [have Customer A and Customer B], and I'm a service provider for both. The two customers have businesses that are close to each other across the street. Both customers physically connect to the same kind of infrastructure. Your internet connection ends up at one of my points of presence, and I have a router there. I don't want to have [two routers that cost $10,000 each]. So, I buy one router, a nice, big powerful one. For all my customers, I create these VRFs. I chop this router up for my customers.
If you're Customer A, I'm going to create a VRF called Customer A, and all your routing is going to happen in there. Any packets you're forwarding from one of your offices to another office is going to be isolated in there. And the same thing for Customer B. Whatever's happening in there, it'll be private; it'll be isolated. It's [also] possible to share that. I can configure the router to import and export the packet so that [both customers] can talk to each other. But, by default, that doesn't happen. You're your own thing. That's what the VRFs are all about.
What do you think is most challenging for students preparing to take these exams regarding virtualization?
Gargano: It depends. If it's my career, then the challenge is learning about all these evolving and emerging technologies. The challenge there, as a network admin, would be to get wrapped up in all these different technologies.
If the question is more about the exam, then you're lucky because the exam blueprint is pretty specific. It's just a question of focusing on those. One of the challenging things is the ENCOR [Enterprise Network Core Technologies] exam blueprint is big. It's a big course; there's a lot covered in there. If someone said, 'If I read this, will I pass the exam?' I'd say, 'No, that's not enough.' You need to go beyond that.
When it comes to virtualization, I think it would be about getting as much hands-on practice with the [technology] itself. Within the context of the exam, the blueprint is pretty specific, so you can focus in that area. But, if you're going for the exam, I think just focusing on what it says in the blueprint is going to be fine.
What advice would you give to aspiring CCNPs and CCIEs?
Gargano: I think it's a question of practice. We often hear about people who go to the exam, they pass the exam, and they maybe have never worked on the equipment or done a lab or anything like that. That's such a fundamental thing. If you go and sit for an interview and you say, 'Oh, yeah, I'm a CCNP,' and you've never actually played and worked with the [technology], you're going to get found out pretty quickly.
You need to go beyond what's in the book and blueprints as much as possible. The CCIE level is an even deeper one. But, for the CCNP, I think giving yourself the opportunity to expand out of what's covered there will guarantee you a better chance of passing that exam.
What made you want to write this book?
Gargano: I've always been about helping people improve themselves and learn stuff. And there's a big market for people who want help to pass these exams. It's really challenging because there's so many cool resources now, like Udemy and Coursera and YouTube. Some learners like video learning, and some learners prefer having something to look at and read and ponder.
I was happy to contribute a little bit in that space to help people who might be struggling and like the concept of 31 days -- the idea that you give yourself a specific target because a lot of people sometimes start studying and never book that exam. They keep putting it off and putting it off. That's one of the things I often tell my students. When we're wrapping up the course, [I tell them to] book that exam. Go ahead and pick a date a month from now, whatever you need, but put a date there. Put a deadline so you've got something to work toward.