Hi all, > 3.2. Benefits of Network Overlays > > [...] Some examples of network overlays are tunnels such > as IP GRE [RFC2784], LISP [I-D.ietf-lisp] or TRILL [RFC6325].
Three comments things on the above: - I don't think the "tunnel" term is helpful to designate LISP or TRILL, and some possible uses of GRE - the encapsulation in itself does not define how you build an overlay, so I don't think the example of GRE RFC2784 is not an appropriate example; first of all, you can put different payloads in GRE (e.g. IP, Ethernet, MPLS, and of course many more), in some cases (e.g MPLS in GRE) there are even other possible payloads; second, the payload carried is also not enough to describe how the overlay is built (e.g. you can use GRE keys to separate tenants, or you can use something else; for MPLS-in-GRE with an Ethernet payload, you could build the overlay with VPLS (different flavors) or with E-VPN ). - maybe the wiser is to not rush into the gap analysis, and not use some approaches as examples, rather than others. > The use of a large (e.g., 24-bit) VNID would allow 16 million > distinct virtual networks within a single data center, eliminating > current VLAN size limitations. This VNID needs to be carried in the > data plane along with the packet. Adding an overlay header provides > a place to carry this VNID. I find the above very misleading, since you can very much achieve the same result without having a "large" 24-bit VNID in the dataplane. > External communications (from a VM within a virtual network instance > to a machine outside of any virtual network instance, e.g. on the > Internet) is handled by having an ingress switch forward traffic to > an external router, where an egress switch decapsulates a tunneled > packet and delivers it to the router for normal processing. This > router is external to the overlay, and behaves much like existing > external facing routers in data centers today. If this is all we'll achieve with NVO3, then I certainly wouldn't put it in a section called "benefits of overlays", but rather in a section called "Drawbacks of NVO3"... ;-) More seriously, beyond the fact that the paragraph above looks misplaced in this section, I think the problem statement should insist on the feasibility of efficient interworking with external networks. Being limited to an architecture where a box "decapsulates NVO3" to some VLAN toward another box which then has to map this VLAN in the proper context, will actually be a pain to manage. The provisioning efficiency brought by NVO3 is also needed for these interconnects, and the problem statement should I think reflect this: the problem statement should include the ability to terminate NVO3 directly on a router. > Overlays are designed to allow a set of VMs to be placed within a > single virtual network instance, whether that virtual network > provides the bridged network or a routed network. (typo above: s/the bridged network/a bridged network/ ? ) -Thomas _________________________________________________________________________________________________________________________ Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration, France Telecom - Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci. This message and its attachments may contain confidential or privileged information that may be protected by law; they should not be distributed, used or copied without authorisation. If you have received this email in error, please notify the sender and delete this message and its attachments. As emails may be altered, France Telecom - Orange is not liable for messages that have been modified, changed or falsified. Thank you. _______________________________________________ nvo3 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nvo3
