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

[Jennifer Rexford <jrex at CS.Princeton.EDU>]

Joe,
> A _virtual network_ is a network composed of tunnels, virtual hosts,
> and/or virtual gateways. A tunnel is a link that encapsulates for
> control purposes, but reaches only the existing endpoints (this
> distinguishes it from how a native L3 uses a native L2). A virtual host
> is a network node that adds or removes headers, and has at least one
> tunnel endpoint in a given virtual network. A virtual gateway is a
> network node that does not add or remove headers, and has at least two
> tunnel endpoints in a given virtual network.

That strikes me as a definition of a virtual network, rather than a 
definition of network virtualization.  You could view network 
virtualization as a *platform* for supporting multiple virtual network 
topologies on a shared substrate -- that is, a platform that has the 
ability to support or "host" (multiple) virtual topologies (each 
consisting of multiple virtual nodes and virtual links) running directly 
in the underlying substrate.  For example, while an (IP) network like 
the Internet can carry packets on behalf of overlay links (i.e., 
tunnels) between end hosts that span multiple underlying router hops, 
that does not necessarily mean that the Internet substrate itself 
supports network virtualization, because the overlay links might run 
over (rather than in) the underlying substrate, and the virtual nodes 
run outside of the substrate (e.g., on end hosts).

-- Jen
> - ---
>
> Virtual networks have three primary uses:
>     - protection
>         allow new services/protocols to be deployed on a subset
>             e.g., testbeds, incremental deployment
>         keep experiments from leaking out
>             e.g., testbeds
>         keep others' uses from affecting a given use
>             e.g., emergency services, guaranteed capacity,
>             privacy/authentication
>     - concurrency
>         shared use of common infrastructure
>     - abstraction
>         simplify the topology (e.g., LISP/NERD)
>         support application-specific topology (e.g., P2P)
>
> I don't think these uses have anything to do with the definition,
> though; they come out of the definition, rather than drive it.
>
> Joe
>
>
>
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