Mehmet is pointing to what I remember. I think we should break down the definitions in terms of Policy Mechanism Behavior.
For example: A mechanism for a L2 CUG is a VLAN-ID The policy is that a Ethernet network logically separates traffic from between VLANs on the same network. A closed user group is a behavior where there is free communication between a group. For example MAC based services on a Ethernet VLAN. Don From: [email protected] [mailto:[email protected]] On Behalf Of Larry Kreeger (kreeger) Sent: Friday, September 28, 2012 11:39 AM To: [email protected] Subject: Re: [nvo3] What is CUG model was RE: Push or pull? I think Mehmet has a subtle, but valid point about the term CUG. A CUG is a group of users, while a VN provides connectivity between those users. There is one other aspect of a VNs that we had previously discussed, which is that TES connected to different VNs can use overlapping addresses. This is an aspect that goes beyond what users can communicate with each other to what addresses they can use. Presumably, if one were to allow two members of different CUGs to communicate (by policy), then the addresses used by the members of the two CUGs better not overlap. However, if a gateway is used to interconnect two VNs, then that gateway could also provide a NAT function to allow communication between TES on the two VNs even if they overlap. So, perhaps address overlap is another distinction between VNs and CUGs? This leads me to a question about using "policy" (without a gateway) to allow two CUGs to communicate. Can this "policy" also define NAT to allow overlapping addresses between two CUGs? Thanks, Larry From: <Toy>, Mehmet <[email protected]<mailto:[email protected]>> Date: Friday, September 28, 2012 7:17 AM To: Kireeti Kompella <[email protected]<mailto:[email protected]>>, Thomas Narten <[email protected]<mailto:[email protected]>> Cc: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Subject: Re: [nvo3] What is CUG model was RE: Push or pull? CUG term has been used since the days of X.25. To me CUG only represents entities/users that are on the network (i.e. VN), not the network or a set of connections making the virtual network. On the other hand, VN represents the network or a set of connections making the virtual network, but not the users on the network. Mehmet From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Kireeti Kompella Sent: Friday, September 28, 2012 9:36 AM To: Thomas Narten Cc: [email protected]<mailto:[email protected]> Subject: Re: [nvo3] What is CUG model was RE: Push or pull? Hi Thomas, On Sep 28, 2012, at 6:09, Thomas Narten <[email protected]<mailto:[email protected]>> wrote: This discussion is interesting, but I still have not seen an answer to the question: what is (or is there) a difference between a VN and an CUG? No difference. If there is no difference, that would be great, because then we can use the terms interchangably. If there are differences, we need to understand what those differences are, or there will be confusion in our discussions. For clarity, we should define VN in some draft (framework?), state that VN and CUG are the same, but stick to using one term, preferably VN. Note that Wikipedia defines CUG as follows: Closed User Groups are groups of GSM<http://en.wikipedia.org/wiki/GSM> mobile telephone<http://en.wikipedia.org/wiki/Mobile_telephone> subscribers who can only make calls and receive calls from members within the group. Any other calls would be rejected. The definition is pretty close, but it goes to show that CUG comes with overtones that may confuse people. One refinement might be to define L2 and L3 VNs off the base definition of VN. Yakov Rekhter <[email protected]<mailto:[email protected]>> writes: There is a definition of L2-based CUG in draft-rekhter-nvo3-vm-mobility-issues Thomas, the reference I gave below about where L2-CUG is defined is wrong -- not the EVPN draft, but the one above. <rest snipped> Kireeti
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