Pedro Roque Marques <[email protected]> writes: > I object to the document on the following points: > > 3) Does not discuss the requirements for inter-CUG traffic.
Given that the problem statement is not supposed to be the requirements document,, what exactly should the problem statement say about this topic? <[email protected]> writes: > Inter-VN traffic (what you refer to as inter-CUG traffic) is handled > by a straightforward application of IP routing to the inner IP > headers; this is similar to the well-understood application of IP > routing to forward traffic across VLANs. We should talk about VRFs > as something other than a limitation of current approaches - for > VLANs, VRFs (separate instances of routing) are definitely a > feature, and I expect this to carry forward to nvo3 VNs. In > addition, we need to make changes to address Dimitri's comments > about problems with the current VRF text. Pedro Roque Marques <[email protected]> writes: > That is where again the differences between different types of > data-centers do play in. If for instance 90% of a VMs traffic > happens to be between the Host OS and a network attached storage > file system run as-a-Service (with the appropriate multi-tenent > support) then the question of where are the routers becomes a very > important issue. In a large scale data-center where the Host VM and > the CPU that hosts the filesystem block can be randomly spread > where is the router ? Where is what router? Are you assuming the Host OS and NAS are in the different VNs? And hence, traffic has to (at least conceptually) exit one VN and reenter another whenever there is HostOS - NAS traffic? > Is every switch a router ? Does it have all the CUGs present ? The underlay can be a mixture of switches and routers... that is not our concern. So long as the underlay delivers traffic sourced by an ingress NVE to the appropriate egress NVE, we are good. If there are issues with the actual path taken being suboptimal in some sense, that is an underlay problem to solve, not for the overlay. > In some DC designs the problem to solve is the inter-CUG > traffic. With L2 headers being totally irrelevant. There is an underlying assumption in NVO3 that isolating tenants from each other is a key reason to use overlays. If 90% of the traffic is actually between different tenants, it is not immediately clear to me why one has set up a system with a lot of "inter tenant" traffic. Is this is a case we need to focus on optimizing? But in any case, if one does have inter-VN traffic, that will have to get funneled through a "gateway" between VNs, at least conceptually, I would assume that an implementation of overlays would provide at least one, and likely more such gateways on each VN. How many and where to place them will presumably depend on many factors but would be done based on traffic patterns and network layout. I would not think every NVE has to provide such functionality. What do you propose needs saying in the problem statement about that? Thomas _______________________________________________ nvo3 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nvo3
