Now what is in a V NFI or network functions?
Virtualization is the idea that you've virtualized network devices and network functions.
He has a document explaining and a V and it's very good if you're interested in getting into the details.
This is from the.
SD in an open flow World Congress in 2012.
But you don't need to spend a lot of time going through this document.
That's only of interest.
I'll explain briefly what NFI is for the CNA exam.
Service have been virtualized for years.
So as an example, here I'm running a Cisco core manager.
As a virtual machine in Essex, I.
And I couldn't connect to that server as an example using a web browser and then configure the server.
Servers are now virtualized in the cloud, and I can spin up instances of servers very, very quickly
using Amazon EC2 or Microsoft Azure or the Google Cloud.
The networking, however, has generally in the past sold physical boxes for functions.
So in other words, if you wanted a firewall, you would buy a physical piece of hardware that provides
a function or a set of functions to you.
In this case, firewall.
If you wanted a VPN device in the past, you would buy a VPN concentrator or a device dedicated to creating
VPN connections.
In the past, if you wanted a load balancer, you would buy a physical load balancer or a session border
controller.
You would buy a physical device for that function.
Rudders such as a piranha are physical devices.
If you want a router, you would buy a physical rudder.
Now the idea with network virtualization is we virtualize network devices in the same way that we virtualized
servers.
So we take these physical devices and we run them as a virtual appliances on physical servers.
And he has an example once again of doing that.
I've got a single physical server running iSCSI, but here I've got multiple Cisco CSR routers running.
As a virtual machines.
In Essex if I use the command show ip ospf neighbor.
Notice I see multiple neighbor relationships.
So this device, 19216812 or three is a physical router.
So what I'll do is telnet to that physical router and I'll log in.
Notice this is an 1841, so show version shows me that this is an 1841 physical router show.
Diag, as an example, shows me the physical components in that router, but back on the iSCSI router
show version shows me that this is a CSR rather show diag.
It doesn't show the same information.
Because this is a virtual router, not a physical router.
You can see as an example that it's a CSR 1000 ve so show ip ospf neighbor once again shows me different
neighbor relationships and I could telnet to another router.
This Rada is a 1941.
So this is another physical Rada.
So what's the point rather than running physical rotters?
Why not run multiple virtual routers in the same way that you run the virtual servers?
The concept of having a physical device for every function doesn't make sense in today's world.
As I demonstrated, it only takes a few minutes to spin up a virtual machine.
On Amazon, it's been easy in the past to spin up virtual servers and allocate a virtual disk space
or storage.
But one of the big problems in the past has been that networking required physical devices.
So just like years ago, server administrators no longer have a physical server per application, such
as email or web services.
We now in networking don't have a physical device.
For a physical function, we can run virtual routers and virtual firewalls as virtual machines alongside
our virtual servers.
One of the advantages of doing that as an example is you could run a virtual firewall in front of every
virtual server if you needed to.
You can implement what's called micro segmentation, where you segment your network down into tiny subnets
or tiny segments to reduce broadcasts to implement better security and other benefits.
It doesn't make sense today to have a physical network device for every function.
If you have the requirement for a firewall, it doesn't make sense to buy a physical firewall for your
virtual servers.
In some cases, it makes sense to buy a virtual firewall that you run on the same hypervisor as your
virtual servers.
So this is the idea of network function virtualization.
We firstly virtualize an appliance such as a router or a firewall or a load balancer, but then taking
it a step further, we can also load balance functions.
So if all you need is to implement something such as DRP or HSP, it doesn't make sense to run a full
operating system in the server world.
We have the concept of Docker and the same kind of idea is now starting to happen in networking where
we just run functions rather than entire operating systems.
I've added some videos about Docker to the course.
They are only of interest and are not part of the CCNA exam.
So if you're interested in learning some real world stuff about Docker and newer technologies, have
a look at those videos.