So what I heard/read is this: draft-rekhter-nvo3-vm-mobility-issues-02.txt: An L2-Closed User Group has some defining attribute (VLAN-ID for Ethernet) that allows free communication between members. - IP address assignment is based on L2-CUG.
- A Virtual Machine(VM) may belong to one or more L2-based CUGs.(One VID per L2-CUG) (One IP Prefixes per CUG) - And Policy can allow a VM in one L2-Based CUG to communicate with other VMs in other CUGs through IP. - So the mechanism enabling a L2-CUG is a VLAN. And I believe a Route Target in a EVPN is a mechanism that can extend the VLAN. (extending the L2-CUG over IP WAN). It would follow that a Route Target in an L3 VPN can extend and interconnect an IP subnet(s) (over the IP WAN) and this is (I think) independent of the L2-CUG although it could also be aligned with the L2-CUG. So getting back to Push or PULL An L2-CUG uses a VLAN as a Push Mechanism for Learning (Frames are pushed). An IP-subnet on a L2-CUG can use ARP (Pull) (ARP responds with IP address). The IP-Subnet could also use routing and go between L2-CUGs. Between IP-Subnets we use routing (IGP or BGP + Policy between subnets) I'd say EVPN RT is primarily push (RT + VLAN) = L2-CUG. L3 VPN is Push RT + Routing. This aligns with those that say a VM can talk to other VMs in other Virtual Networks only at IP. Push and Pull is not so clear cut. I can sort this scheme out in my head. But I don't know other alternative schemes. Perhaps delete EVPN and L3VPN and use something else? At is level it makes some sense to me. Thanks, Don -----Original Message----- From: Kireeti Kompella [mailto:[email protected]] Sent: Thursday, September 27, 2012 7:26 PM To: Thomas Narten Cc: Fedyk, Donald (Don); [email protected]; Lucy yong Subject: Re: [nvo3] What is CUG model was RE: Push or pull? Hi Thomas, On Sep 27, 2012, at 14:31, Thomas Narten <[email protected]> wrote: > One of the things I've been meaning to clarify here is what is the > defintion of a CUG? > > In offlist discussions I've had, I've come to the conclusion that a > CUG is the same thing as a VN. That is, it's a set of machine that are > administratively placed into a group and are allowed to communicate > with each other, but not with others outside of that CUG. > > Correct? Almost. Entities inside a CUG may communicate to entities outside through a policy specified by the appropriate administrator. the default policy is as you say: no communication. > And, RFC 4364 says: Essentially, RFC 4364 defined an L3 CUG, and the EVPN draft an L2 CUG. Kireeti >> Suppose it is desired to create a fully meshed closed user group, >> i.e., a set of sites where each can send traffic directly to the >> other, but traffic cannot be sent to or received from other sites. >> Then each site is associated with a VRF, a single Route Target >> attribute is chosen, that Route Target is assigned to each VRF as >> both the Import Target and the Export Target, and that Route Target >> is not assigned to any other VRFs as either the Import Target or the >> Export Target. > > Is there another (different?) definition of CUG? > > Thomas > > _______________________________________________ > nvo3 mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/nvo3 _______________________________________________ nvo3 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nvo3
