Larry, Distributed L3 gateway is very useful and some vendors already implement that. Current framework also includes L2/L3 service as Marc agrees to add the text I proposed although we did not explicitly define as a service type.
Current architecture clear states NVE and NVA roles, i.e. NVE performs forwarding, and NVA performs routing. If NVA is not able to distribute routing policy to NVE at all, I do not know how NVA can perform route distribution control? If NVA only supports simple inner to outer mappings, how can NVE get information to perform local forwarding? Thanks, Lucy -----Original Message----- From: Larry Kreeger (kreeger) [mailto:[email protected]] Sent: Friday, October 18, 2013 5:00 PM To: Thomas Narten; Lucy yong Cc: [email protected] Subject: Re: [nvo3] Distributed Gateways [was Re: NVO3 Architecture document] Hi Thomas and Lucy, The WG needs to think hard about this one. Support of a distributed L3 gateway function between L2 VNs is a significant increase in scope of the NVA, and the NVE to NVA protocol. Where we had previously stated L2 service or L3 service and pretty much left a combined L2/L3 service as an exercise for the reader, we would now be adding whatever mechanisms are needed to the protocols. We will need to add cases for L2 service, L3 service and L2/L3 service. We no longer have simple inner to outer mappings, but now need NVEs to do MAC rewrites, local NVE ARP termination, and multiple lookups depending on the destination MAC address (first L2, then potentially L3). We will also need to distribute two different VN identifiers (one for L2 and one for L3), and somehow convey the containment relationship between the two (multiple L2 VNs within one L3 VN). While I think this is all very useful, I just want to make sure the WG agrees to this since I feel it is a significant change/increase in scope from my perspective. Thanks, Larry On 10/18/13 2:52 PM, "Thomas Narten" <[email protected]> wrote: >Hi Lucy. > >Lucy yong <[email protected]> writes: > >> Section 5.3 describes gateways. IMO: it misses an important use >> case. A Gateway, say overlay gateway, may be used to interconnect >> two or more overlay VNs. In this case, the traffic traversing >> between two overlay VNs must go through the gateway where the policy >> can be enforced. Furthermore, it is possible to implement >> centralized or distributed overlay gateway. The latter has overlay >> gateway function implemented on NVEs. Thus, it requests the cross-VN >> policies to be distributed to NVEs. > >> Current section seems very focus on overlay VN interconnect a >> non-overlay network, which centralized gateway architecture is >> practical. But in overlay networks, both centralized or distributed >> are possible and depend on the applications. > >Agreed. I propose adding a new section after 5.3 that says: > > <section title="Distributed Gateways"> > <t> > The relaying of traffic from one VN to another deserves > special consideration. The previous section described > gateways performing this function. If such gateways are > centralized, traffic between TSes on different VNs can take > suboptimal paths, i.e., triangular routing results in paths > that always traverse the gateway. As an optimization, > individual NVEs can be part of a distributed gateway that > performs such relaying, reducing or completely eliminating > triangular routing. In a distributed gateway, each ingress > NVE can perform such relaying activity directly, so long as > it has access to the policy information needed to determine > whether cross-VN communication is allowed. Having individual > NVEs be part of a distributed gateway allows them to tunnel > traffic directly to the destination NVE without the need to > take suboptimal paths. > </t> > <t> > The NVO3 architecture should [must? or just say it does?] > support distributed gateways. Such support requires that > NVO3 control protocols include mechanisms for the > maintenance and distribution of policy information about > what type of cross-VN communication is allowed so that NVEs > acting as distributed gateways can tunnel traffic from one > VN to another as appropriate. > </t> > </section> > >Thoughts? > >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
