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

[Andreas Wundsam <andi at net.t-labs.tu-berlin.de>]

Hi,


Joe Touch schrieb:
> Nick Feamster wrote:
> > 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?") 
>
> If that's true, then why is the Internet not already a virtual net, 
> e.g., supporting different transport protocols over IP? IP is shared by 
> different transports. Similarly, ethernet supports different network 
> protocols.

I would think think that the key difference is the level of transparency 
and information hiding offered. Virtualization generally is transparent 
to the user, layering is not. TCP knows it is running on top of IP. A 
network stack running in a virtualized network would believe itself to 
be running alone on a dedicated physical infrastructure, when in fact it 
could coexist with other networks on the same hardware. The analogy with 
Virtual Memory holds here - a program running on virtual memory does not 
have to know other processes are existing on the system -- all it sees 
is a flat address space starting at 0. Hence, I would consider VLANs, 
Tunnels etc. all proper mechanisms for virtualizing links, but only in 
combination with a mechanism that hides their existence and specifics 
from the user.


Best regards,

Andi Wundsam
TU Berlin

--
Andreas Wundsam
Technische Universität Berlin, Deutsche Telekom Laboratories

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