(again, speaking as an individual participant): On 7/15/2010 9:36 AM, Didier Colle wrote:
Dear Joe, all,I tend to think of a logical device as not really adding to the capabilities of a physical one, though, whereas a virtual one seems to (at least to me).Please explain. What capabilities are you referring to? So far, I think most people on the list have expressed a virtual network having the same or a subset of the capabilities of the network. Do you agree with that? And remains that statement true for a virtual device rather than virtual network?
A physical network can't be relocated while running. A virtual one can.A physical network doesn't ensure separation from other physical networks; a virtual one should, IMO.
From your previous post today, these capabilities are not apparent.1.c. what is the characteristic behavior/capability of the resulting system? I think that the defining characteristic of a VN is that it allows an existing network to concurrently emulate another, distinct and separate network.
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Is that a characteristic/capability of the virtual network (VN) or of the underlying existing network?
The VN. Without the VN, no such emulation would occur, IMO.
Maybe these are really just two aspects of a single thing, i.e., I would differentiate between: - a device which does not map 1:1 to a physical entity (could be a part of one, a group of many, or a group of parts) - a device which provides supports virtual networking Since we call the latter "virtual networking" (the name of this RG), I would propose that the latter would be the virtual device, and the former be the logical one.Hmm... so the resulting question is: What is virtual networking? ;-)
I had proposed a definition - which is a network composed of tunnels. The rest, IMO, is largely in support of that one distinguishing characteristic.
I don't think of it as a 'specialized form', but rather the fact that a single virtual router CANNOT be mapped onto a single physical device with no other logical components. I.e., a virtual router needs a base router to connect to the links of the tunnel. A virtual host needs a base router (as well) for the same reason.
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Really? In your previous post you said: "A virtual link is the easiest to define - it is a tunnel over some existing network path, i.e., with an additional layer of encapsulation that is used solely for the VN, but which is otherwise not needed. A virtual router forwards packets between virtual links. " So, virtual link is encapsulated (e.g., by tagging with a VLAN-ID?) to allow multiplexing: is this something the virtual router cannot do (although invisible to the user/owner of the virtual router)?
A virtual router can encapsulate, but doesn't know what to do with the encapsulated packet, IMO. At some point the packet needs to go out a physical interface, and I don't think virtual routers own any physical interfaces.
Do you need for that another "base" router?
No; that's what I needed the base router for in the first place. Joe
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