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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.

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.
- ---

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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