Re: [nvrg-bof] What is Network Virtualization?

["Nick Feamster" <feamster at gmail.com>]

I agree. unneling is a *mechanism* by which links can be instantiated
over a shared physical infrastructure, but the question "What is
network virtualization?" is really a what question (tunneling answers
"How?", not "What?")

I believe a key aspect to network virtualization is the generic aspect
of sharing: VN allows multiple networks that conceivably could be
implemented on the physical infrastructure itself to be run on a
common physical infrastructure.

Beyond that, we can ask questions about mechanism, including:
* How are links and nodes virtualized?
* How is isolation enforced?
* How are headers manipulated?
* Should the VN expose different kinds of abstraction/interfaces (to
simplify designs at higher layers)?

But I don't think network virtualization scheme implies certain
mechanisms (e.g., tunneling, manipulation of headers, etc.).
Mosharaf's definition looks about right.  We could probably factor out
the mention of "providers", since network virtualization doesn't
necessarily imply a distinction between the providers of physical
infrastructure are distinct from those creating the virtual networks.

To me, the keys are (1) Sharing and (2) Exposing abstractions that
provide the appearance of running on the physical network itself.

-Nick

On Fri, Jun 20, 2008 at 12:59 PM, Vytautas Valancius <valas at gatech.edu> wrote:
> Hi folks,
>
>> I agree in the sense that NV is a means to create a VM. I disagree about the
>> "shared substrate" part - it's the tunnels that define the virtualization in
>> my definition; how devices are shared is not directly relevant (that's
>> mechanism; see the end of this post).
>
> Tunnels is just one of the ways to use shared substrate. 'Shared
> substrate' is generic term and I don't think it implies how devices
> are shared.
>
> I thought the goal is to come up with the definition for the term
> 'network virtualization'. Mosharaf's definition seems pretty accurate,
> but probably too specific for some tastes. Very generic variant of the
> same definition, that supports anything is is:
>
> ---
> Networking environment supports network virtualization if it allows
> multiple virtual networks to co-exist together.
> ---
>
> IMHO that's a bare minimum. Sharing is mandatory, otherwise we would
> call it emulation. Based on our preferences one can drop in phrases
> like 'heterogeneous' to imply different guest network technologies,
> dynamic set-up, to highlight ease of use, providers, end users,
> gateways, etc. to indicate some usage scenario.
>
> Sincerely,
> Vytautas Valancius
> Georgia Tech
>