Information for an interview about MPLS, DMVPN, IPAM, SolarWinds Or...

[LetMePass]

Hello Cisco Community,

Going to get my first interview for a position that requires a CCNA (Certified since a month), on Thursday 18.1

I'm conducting my own research, but to you, is there anything you think is crucial to know so I don't look clueless?

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What will you do

You will be primarily responsible for configuration, management and troubleshooting Cisco network devices – routers, switches, ASA firewalls, wireless bridges and access points. We are responsible for more than 2500 WAN circuits, 3000 Access points, 900 firewalls, 5000 switches and over 8000 servers (both Windows and Linux-based) spread across 6 Data Centers (Europe, North America and Asia). As well as working with Zscaler (cloud-based web filtering solution) and tools such as IPAM, SolarWinds Orion, NetFlow, Cisco Prime, Cisco ISE and others while mainly focusing on the following:

• Deployment and configuration (DMVPN routers, L2/L3 switches, Firewalls, Site-to-site and Remote VPN)
• Change implementation (migrations from MPLS to DMVPN, configuration changes)
• Incident management (communication with major MPLS providers)
• Troubleshooting and monitoring of infrastructure (on Cisco IOS, IOS-XE, NX-OS, ASA and SteelHead)
• Processing general requests from internal customers

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I welcome any comment!

Cheers,

Chris

[Ruben Cocheno]

@LetMePass 

If you passed the second round/technical interview is because your CV resumes with the role, so don't panic. Answer the questions asked directly and if you don't remember or just don't know just say it. Best of luck!

This seems like a support/administrator role, so probably the way you approach the problem including managing 3rd party relations during your troubleshooting is what the Hiring Manager is looking for. 

[Georg Pauwen]

Hello,

sounds like a nice position. If you don't know any of the above devices/technologies, try and read up on them so you have at least a general idea of what they are used for.

That said, just reading your post, I would hire you. You seem to have the right attitude. Good luck with the interview !

[LetMePass]

Hello guys,

Thank you for your encouragements.

I will put here what I found so far for DMVPN and MPLS for others users on the forum.

DMVPN:

It's a Hub & Spoke network, a full mesh of GRE tunnels between all of the routers and the WAN. It allows traffic between spokes to flow directly between the spokes without having going through the hub.

In typical Star topology there is no tunnel going between spokes or end points. 

But with DMVPM even though it does use a hub and spoke design, it allows the spokes to build these dynamic GRE tunnels between them.

The whole dynamic piece means that we as administrators, we don’t have to come onto the routers and manually add the tunnels so in a traditional GRE tunnel if I wanted router 2 to have a tunnel to the router 4. I would have to go to router 2 and I would have to say interface tunnel 0; to specify IP address; to specify  tunnel source; to specify tunnel destination.

So if I was to do everything traditionally I would have to go to on to router 2 and I would have to manually configure the tunnel between router 2 and 4 but with DMVPN, I don’t have to do that, 2 and 4 can form the tunnel automatically.

When it comes down to DMVPN, the only tunnel that you have to manually configure is the tunnel going back to the hub so you go on each of the spokes and you are going to manually configure this GRE tunnel going back to the hub and the tunnels between the spokes is pretty much hands off everything is done dynamically.

This is why DMVPN is so popular in large WAN deployments because here we have a small design where we only have 1 hub and 3 routers. But imagine a wind deployment where you have 1 hub and 400 routers. All you have to do is configure each of the 400 spokes to connect back to the hub which is a pretty simple conversation. But then you don’t have to configure all the tunnels between the spokes. They are going to be the one building/destroying the tunnels if they need.

Once more time that is why DMVPN is so popular it allows your network to grow, you can still accomplish the full mesh requirement without having to manually configure tunnels between all spokes. The only thing you do is to configure the tunnel going to the hub.

Source: https://www.youtube.com/watch?v=Znxhhc1QwMg&ab_channel=CiscoGenius

MPLS:

Multiprotocol Label Switching, method of efficiently routing (speed up traffic) data across networks (WAN).

Designed as an alternative to traditional IP routing, MPLS determines the entire route of a packet per unit of data. At the first router the packets reaches, MPLS assigns a short 32-bit label to the packet header, which subsequent routers used to forward the packet along its route.

IP routing on the other hand, requires each router to individually inspect a packet's destination before determining which router it will go to next. This is a time consuming process, which can degrade the performance of a real time application like voice and video. MPLS is notable for its independence from any one protocol or transport medium. It works over IP, Ethernet, Asynchronous Transfer mode, frame relay, among others. MPLS delivers guaranteed performance for real-time traffic and time-sensitive applications but it’s expensive and complex to implement.

Source: https://www.youtube.com/watch?v=n1zaUNGgIIs&ab_channel=EyeonTech