Dear Joe,- why is the router to be a virtual one? I understand a virtual router as a virtual machine which certainly can manage a real network. Since the router does not change anything, that the additional indirection information must initially be understood in some real manner, why would the routers have to different?
I suppose this may result from a vision of a network map like in a NIMROD with the information attached to the nodes. But if you consider that the information are attached to the virtual adjencies you do not need any node related information. You can compute presence, throughput and delays at related adjencies ends. This is more accurate as they may depend on the machine dynamic allocation to the VN resources for that node. The interest is that the difference between the I/O of one way of a virtual adjency gives the line entropy which may be more important to VN path optimization than node load?
- Interested to understand what difference you make between the added indirection information and presentation layer? My first guess is that they are the same except that you push a little more on what presentation is used to be considered in IETF ?
- any objection to have this indirection information made conditional in order to build dynamic VN? Depending on the router I come through I can select one routing or another one, or multiplicate (for example for security reasons or to support multicast or multihoming) ?
- can this indirection information also be virtual in your mind ? So I may use an addressing which is dedicated to the VN ? Or that can be dynamic.
- would you have an idea for a place where to locate that indirection information in packet headers ?
- one of the point I rose about multi-level addressing can also be discussed here.
You call a VH a place where the indirection information can be changed. What about "changed or should have been adequately changed". Let suppose the indirection information encapsulate a second level indirection. Now you have an OPES attached to the adjency (a shim at one of the I/O). If the indirection value the packet carries is the VH virtual address, the OPES can remove it, so the VH can directly act as a gateway using the new indirection?.
jfc At 14:55 22/06/2008, Joe Touch wrote: Based on exchanges with a few people on the list, I'll revisit my
initial proposal.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"Additional notes: - network virtualization describes the process of creating virtual networks, i.e., NV is the process VNs are the artifact I define NV and VNs via the artifact created, because NV is then most generally defined: NV is *any* process or mechanism that creates (enables the creation) of VNs A _VN_ is a network composed of virtual links, virtual hosts, and virtual routers. Virtualization of links, hosts, and routers is accomplished by adding a layer of indirection in the names and/or addresses associated with each. A VL encodes this indirection sufficient for use by VHs and VRs; VHs and VRs uses this indirection information to associate with a VL. Additionally, a VH is a network node that adds or removes indirection information, and is associated with at least one VL in a given VN. A VR is a network node that does not add or remove indirection information, and is associated with at least two VLs in a given VN. The rest, I beleive, remains a reasonable summary of the capabilities of VNs:--- 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 have not listed mechanisms that support VNs, i.e., NV mechanisms yet. These might be summarized as: NV mechanisms: - partitioning (as in Clonable Stacks in hosts/routers, and VPN IDs, VLAN IDs, and tunneling in links, etc.) - aggregation (channel bonding in links, NAT-like services at the edge of server farms and cluster computers, etc.) - combinations of the above Joe
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