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

["Martin Stiemerling" <Stiemerling at nw.neclab.eu>]

Hi Joe, all,

> -----Original Message-----
> From: nvrg-bounces at listserv.gwdg.de 
> [mailto:nvrg-bounces at listserv.gwdg.de] On Behalf Of Joe Touch
> Sent: Tuesday, June 17, 2008 7:02 PM
> To: nvrg at listserv.gwdg.de
> Subject: Re: [nvrg-bof] What is Network Virtualization?
> 
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> 
> 
> Mosharaf Chowdhury wrote:
> | Thanks Martin for bringing up this matter. I had the following 
> | definition for network virtualization in my mind for quite 
> a while. To 
> | my understanding most of the aspects are covered. I was 
> looking for a 
> | one-liner, but now it seems a bit too long for one line :)
> |
> |
> |     Network virtualization is a _networking environment_ that allows
> |     _multiple service providers_ to _dynamically compose_ _multiple
> |     heterogeneous virtual networks_ that _co-exist together_ in
> |     _isolation_ from each other, and to deploy _customized 
> end-to-end
> |     services_ _on-the-fly_ as well as _manage_ them on those virtual
> |     networks for the _end-users_ by _effectively sharing_ 
> and _utilizing
> |     underlying network resources_ _leased_ from _multiple 
> infrastructure
> |     providers_.
> 
> This focuses on providers; that's not necessarily relevant at all.

+1. I consider this as some business plan but not part of the defintion

> 
> Resource sharing alone isn't sufficient either, since that's 
> already accomplished by provisioning, e.g., different sonet 
> paths supporting different ISPs on the same infrastructure.
> 
> Some acid tests for a definition:
> 	- it should support VPN, PPVPN, and overlays as VNs
> 	- it should not define the native Internet as a VN
> 		i.e., it must distinguish layering from
> 		"overlayering"
> 
> IMO:
> - ---
> 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.

I believe that this is the definition of a virtual network but not necessarily network virtualisation. The first sentence is already ruling out VLANs on ethernet (which could be one technique for network virtualization on that link layer). However, for virtual networks the defintion fits perfectly. 

> - ---
> 
> 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.

Sure and they also apply IMHO to network virtualization (e.g. VINI has as far as I understand the same uses).

  Martin