NICs on a virtualization box

[techlists at phpcoderusa.com]

This begs the question, is there a niche for being exclusively a web 
server admin and can we drill down to Linux exclusively?


On 2022-04-20 10:20, Snyder, Alexander J wrote:
> 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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