> I am > presuming that VN to physical gateways are not distributed gateways, but > VN to VN gateways could be distributed.
I would not presume the former, although this discussion has been primarily about the latter. In particular it is definitely possible that different NVEs in a data center could have different preferred routes to the public Internet, so that a distributed implementation of the default gateway for IP could result in better usage of that external connectivity to the public Internet. > >> - Assuming the Distributed Gateway is defined for L3 service, right? Please > >> clarify it in the draft. > > > >Wrong - it applies to both L2 and L3 service. The typical L3VPN > >implementation > >distributes the gateway via the routing infrastructure, so most of the list > >discussion attention has been on L2 service and distribution of the gateway > >to > >avoid triangle or trombone routing. > > LK> But is there a requirement to connect two L2 VNs at L2? I was > assuming that was an uninteresting case. I would agree that it is uninteresting but there are two different L3 concepts in this discussion: "L3 service" provided by VNs envisions an L3VPN class of implementation where there are no L2 adjacencies. L3VPN does have a concept of connectivity among groups, and that connectivity implementation is fully distributed via the routing infrastructure that is used to convey mappings to the NVEs. For "L2 service" the L3 gateway implementation among L2 VNs may be distributed among the NVEs. I believe that the Distributed Gateway discussion will need to encompass both the "L2 service" and "L3 service" cases, and that was the basis of my statement that Distributed Gateways apply to both types of service. Thanks, --David > -----Original Message----- > From: Larry Kreeger (kreeger) [mailto:[email protected]] > Sent: Thursday, October 24, 2013 6:44 PM > To: Black, David; Zu Qiang > Cc: [email protected] > Subject: Re: [nvo3] Distributed Gateways [was Re: NVO3 Architecture > > Hi David and Zu, > > My responses are below, marked with LK>. > > - Larry > > On 10/24/13 1:00 PM, "Black, David" <[email protected]> wrote: > > >> Sorry to jump into this discussion. A few questions on the Distributed > >> Gateways definition. > >> - There is Gateway defined in section 5.3. Do we still need a Gateway when > >> Distributed Gateways are enabled in the NVEs? Maybe yes. Please clarify it > in > >> the draft. > > > >Gateway = function, Distributed Gateway = implementation of Gateway > >function. > > LK> While I agree with the statement above, section 5.3 "Gateways" focuses > mostly on gateways that connect VNs to non-overlay networks. E.g. Connect > a L2 VN to a VLAN, connect an L2 or L3 VN to the internet. It does have > one sentence "Gateways could also forward traffic between a virtual > network and > other hosts on the data center network or relay traffic between > different VNs." which mentions relaying traffic between VNs. I am > presuming that VN to physical gateways are not distributed gateways, but > VN to VN gateways could be distributed. > > > > >> - Assuming the Distributed Gateway is defined for L3 service, right? Please > >> clarify it in the draft. > > > >Wrong - it applies to both L2 and L3 service. The typical L3VPN > >implementation > >distributes the gateway via the routing infrastructure, so most of the list > >discussion attention has been on L2 service and distribution of the gateway > >to > >avoid triangle or trombone routing. > > LK> But is there a requirement to connect two L2 VNs at L2? I was > assuming that was an uninteresting case. > > > > >> - For L3 service, does the Distributed Gateway support routing or > >> forwarding > >> or both? There is no routing protocol running between the Distributed > >> Gateways, right? I assume it is a Yes as it is "relaying" function only. > >> Maybe > >> the Distributed Gateways can be renamed to Distributed Forwarding. Or a > >> clarification needs to be added. > > > >For L3 service, please consult some material on how BGP/MPLS L3VPNs work; the > >answers to your questions can be found there. > > > >> - The text in 5.4 implicitly say that the forwarding policies are updated > by > >> the NVA. This may be ok if user plane routing is not in the scope. If there > is > >> a vR installed in a VM as an user plane router, there may be routing > >> communications between the vR and the Gateway (or Distributed Gateways) > which > >> may have an impact on the forwarding policies. Do we expect any forwarding > >> policies updates due to above data plane routing communications? I hope it > is > >> a No. Maybe it is better to have it clarified in the draft. > > > >Ok, good catch - I agree that this topic should be noted, and the question on > >forwarding policy updates over the virtualized data plane is one for the WG > to > >discuss, IMHO, even though I'd also like to start from a "No" answer. > > LK> I would also like to start from "No". > > > > >Thanks, > >--David > > > > > >> -----Original Message----- > >> From: [email protected] [mailto:[email protected]] On Behalf Of > >>Zu > >> Qiang > >> Sent: Thursday, October 24, 2013 3:13 PM > >> To: Larry Kreeger (kreeger); Thomas Narten; Lucy yong > >> Cc: [email protected] > >> Subject: Re: [nvo3] Distributed Gateways [was Re: NVO3 Architecture > >> > >> Hello, > >> Sorry to jump into this discussion. A few questions on the Distributed > >> Gateways definition. > >> - There is Gateway defined in section 5.3. Do we still need a Gateway > >>when > >> Distributed Gateways are enabled in the NVEs? Maybe yes. Please clarify > >>it in > >> the draft. > >> - Assuming the Distributed Gateway is defined for L3 service, right? > >>Please > >> clarify it in the draft. > >> - For L3 service, does the Distributed Gateway support routing or > >>forwarding > >> or both? There is no routing protocol running between the Distributed > >> Gateways, right? I assume it is a Yes as it is "relaying" function > >>only. Maybe > >> the Distributed Gateways can be renamed to Distributed Forwarding. Or a > >> clarification needs to be added. > >> - The text in 5.4 implicitly say that the forwarding policies are > >>updated by > >> the NVA. This may be ok if user plane routing is not in the scope. If > >>there is > >> a vR installed in a VM as an user plane router, there may be routing > >> communications between the vR and the Gateway (or Distributed Gateways) > >>which > >> may have an impact on the forwarding policies. Do we expect any > >>forwarding > >> policies updates due to above data plane routing communications? I hope > >>it is > >> a No. Maybe it is better to have it clarified in the draft. > >> > >> Have a nice day > >> Zu Qiang > >> > >> > >> >-----Original Message----- > >> >From: [email protected] [mailto:[email protected]] On Behalf Of > >> >Larry Kreeger (kreeger) > >> >Sent: Friday, October 18, 2013 6:00 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 > >> _______________________________________________ > >> nvo3 mailing list > >> [email protected] > >> https://www.ietf.org/mailman/listinfo/nvo3 > > > >_______________________________________________ > >nvo3 mailing list > >[email protected] > >https://www.ietf.org/mailman/listinfo/nvo3 > _______________________________________________ nvo3 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nvo3
