MicroNugget: What is VM-FEX

you know cisco has some terms that are

thrown around in their data center an

awful lot and it can get really

confusing one of those terms is fax you

see it a lot fabric extension and then

another concept built on top of this is

called VM fax let me just take a moment

with you in this micro nugget and make

sure you understand these technologies

so let's look at some Cisco data center

components and let me explain this

concept of effects okay what Cisco means

when they just say fax fabric extension

okay so here you can see we have a B

series chassis and it's filled with

happy happy little B servers B Series

servers of course these are going to

connect to a fabric interconnect and

notice I'm not showing any redundancy

here I don't want to confuse things I

want it to be very clear of what

connects to what and we'll just see it

in a non redundant configuration here as

we explain it so the b-series chassis

connects to the fabric interconnect and

that can connect upstream to a nexus 2k

now you know the nexus 2k is pretty

remarkable it acts as a child to a

parent device that is going to provide

all of the configuration and management

for that so it is going to connect to

something upstream like a nexus 7 k in

our illustration here we call this

device of course the end of Rack device

and we call this child device the top of

rack device for connectivity remember

this child seems like a line card that

is installed locally on the parent even

though it is down there at the top of

the data center rack so fabric extension

refers to this device right here being

outside of that 7 K and acting like it's

internal to the 7 k get it fabric

extension it extends out there too

the top of rack so oftentimes the Nexus

2k will simply be referred to as your

fax Oh what are you using for effect so

I've got the certain model of Nexus 2k

in place for my fabric extension so what

is VM fax well fabric extension to the

VM level on one of these B servers

you'll have let's say four VMs running

yeah you're doing some powerhouse web

work Oracle work whatever so you got

these four different VMs running and

they're on this single B series server

in that B series blade server you put

one of Cisco's fancy virtual interface

cards this virtual interface card will

literally tag each VMs traffic so that

that traffic can be uniquely identified

as it moves upstream so it's this

concept of extending the awareness of

this parent device all the way down to

the virtual machine level we have

virtual machine a right here and this

parent device can recognize the traffic

of that particular virtual machine

thanks to VM fax I said there was

tagging involved and this is called the

ven tag that we are talking about that

is utilized in this virtual machine

effects environment now something that's

really interesting about this is I'll

have a lot of students look at this

concept and they will say gee you know

what I think you're gonna have to be

running something like the Nexus 1000v

and that used to be true that we needed

a technology running like the 1000 V in

order to pull this off except now VM fax

can be implemented all within the

hardware and the hypervisor the traffic

forwarding can go on without the need

for the 1000 V as long as we have

particular hardware

components in place so VFX can be done

with a virtual switch or without a

virtual switch in today's environment so

there you have it

fax and particularly VM fax I sure hope

this micro nugget has been informative

for you and I'd like to thank you for