NICs on a virtualization box

[Snyder, Alexander J]

When I worked as a server admin at GoDaddy.com ... we would create a second
virtual NIC (eth0:1) and configure that with a dedicated IP address that
was in the ARIN block they owned. The switches further up the stream would
handle the NATing and whatnot to make sure that server got the proper data.
I do not know enough about the switches or networking to explain how that
works.

Thanks,
Alexander

Sent from my Samsung Galaxy S22+

On Wed, Apr 20, 2022, 10:04 Keith Smith via PLUG-discuss <
plug-discuss at lists.phxlinux.org> wrote:

> WOW Thanks!!  If we were running a box of VPS's and the box had two NICs
> would the second NIC be redundant just in case the 1st NIC fails.... How
> do multiple NICs on the same box work?
>
> OK so the software layer on the O/S talks to the NIC but is not actually
> assigned to any particular NIC?
>
> Thanks for all the replies, this is very educational.
>
>
>
> On 2022-04-20 09:19, Kevin Fries wrote:
> > Always remember, the network interface from the OS side and the
> > network interface from the hardware side are two completely different
> > concepts.  Other than the fact that they are generally matched one to
> > one, they really have nothing to do with one another.
> >
> > A hardware interface (i.e. on a NIC) is physical, and you have as many
> > as you have.  No way to manufacture more without installing more
> > hardware.
> >
> > A OS network interface is a software construct.  ETH0 (using the old
> > vernacular) generally maps to the first hardware interface, and
> > provides a hook for software to use… most notably the network stack.
> > While it is not done out of the box, there is no restriction to say
> > that two of these constructs can not map to the same back end
> > construct.  So yes, you can have ETH0.1 (again, using the old
> > vernacular)
> >
> > VMWare and other similar virtual machine managers can take advantage of
> > this.
> >
> > The second point you need to get straight in your head is that a fixed
> > IP address is never a construct of the box, but of the Domain Naming
> > Service (DNS) on the network.  It is NAMED that assigns the IP
> > address.  For an interface (software in this case as the hardware’s
> > address is actually the MAC ADDRESS) to have an address, it asks the
> > DHCP server for it.  If the DHCP has been told, always assign this
> > address to this requester, the address is a fixed, reserved, or
> > dedicated IP depending on who is speaking to you.  They all mean the
> > Same thing.
> >
> > So, yes, the number of NICs on a box does not limit the number of
> > network interfaces the OS provides, and yes, each of those interfaces
> > can have a dynamic or dedicated IP address.
> >
> > HTH
> > Kevin
> >
> > Sent from my iPad
> >
> >> On Apr 20, 2022, at 9:51 AM, Keith Smith via PLUG-discuss
> >> <plug-discuss at lists.phxlinux.org> wrote:
> >>
> >> 
> >> Hi,
> >> I'm wondering how VPS servers are configured.  I have a VPS with a
> >> dedicated IP.  I assume I share a box that has a number of virtual
> >> machines and I assume each VPS has a dedicated IP.
> >>
> >> This is a hardware question.  I assume the box has at least 2 network
> >> cards.  So lets say the server has 20 VPS on it and each has a
> >> dedicated IP. Does the box need a NIC for each IP or does the box have
> >> NIC cards that can service/route multiple IPs?
> >>
> >> I have a Dell consumer grade mini tower computer with a single NIC
> >> which is built into the motherboard.  I assume that NIC can only
> >> service one IP address, is that correct or can I install
> >> virtualization software on this computer and use the NIC for multiple
> >> IP's?
> >>
> >> Did I just open a can of worms?
> >>
> >> Thanks in advance for your wisdom.
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