Hi Xiaohu, As an example, an important use case that needs to be addressed is how to "stretch" a subnet across two or more NVO3 domain. If two NVO3 domains connect at two separate sites, then the subnet will be stretched across these NVO3 domains at both sites. Ideally the stretched subnet will make the most optimal use of the interconnect points at both sites -- including using the shortest path between end-stations on either side of the stretched subnet. This is not possible with active/standby solutions. Also the underutilization of resources comes at a significant cost to the operator (inefficient use of resources also creates undesirable costs/tradeoffs for the operator)
Best regards. -- aldrin On Monday, September 24, 2012, Xuxiaohu wrote: > Hi Aldrin,**** > > ** ** > > I can hardly understand your question. Would you please explain it in more > details? **** > > ** ** > > Best regards,**** > > Xiaohu**** > > ** ** > > *发件人:* Aldrin Isaac [mailto:[email protected] <javascript:_e({}, > 'cvml', '[email protected]');>] > *发送时间:* 2012年9月22日 22:44 > *收件人:* Xuxiaohu > *抄送:* Jon Hudson; Lucy yong; Kireeti Kompella; > [email protected]<javascript:_e({}, 'cvml', '[email protected]');> > *主题:* Re: [nvo3] Is the cost of supporting active-active multi-homing on > a per L2VPN instance basis sustainable?**** > > ** ** > > Xiaohu,**** > > ** ** > > Assume a Virtual LAN is formed by the interconnection of an L2 VN in an > overlay domain with other LAN technology (dot1q, TRILL, PBB, etc) and/or > other L2 VN in other overlay domain. In such a case would you mandate > that the interconnection points must be active/standby? What then if the VN > "bridges" with the VN in the other Overlay domain via multiple sites/DC? > Would you pick one site to be the active interconnection point in order to > avoid data plane loops? What then of optimizing ingress/egress? What of > pooling?**** > > ** ** > > Best regards. -- aldrin**** > > > On Saturday, September 22, 2012, Xuxiaohu wrote:**** > > Yes, if the active-active multi-homing on a per L2VPN instance basis was > desired in some cases, vendors could offer their proprietary schemes like > Cisco’s VSS to support that capability. In this way, there is no need to > introduce the complexity into the standard, especially on the data plane > perspective, and therefore other NVEs (i.e., PE routers) which are not > within any active-active redundancy group don’t need to afford that > complexity anymore. **** > > **** > > As for active-passive multi-homing, I fully agree with you that the > active/passive multi-homing on a per physical interface or trunk interface > basis is not welcomed. Hence we could achieve load-balancing among the > physical interfaces or trunk interfaces which are connected to different > NVEs of the same RG (redundancy group) on the basis of VLANs. For example, > a dual-homed device (DHD) is multi-homed to NVE1 and NVE2 and it is > configured with two VLANs (say VLAN x and y) on its physical NICs in a > bond, NVE1’s corresponding interface is active for VLAN x while NVE2’s > corresponding interface is active for VLAN y…**** > > **** > > Best regards,**** > > Xiaohu**** > > -**** > > *发件人:* Jon Hudson [mailto:[email protected]] > *发送时间:* 2012年9月22日 17:16 > *收件人:* Xuxiaohu > *抄送:* Aldrin Isaac; Lucy yong; Kireeti Kompella; [email protected] > *主题:* Re: [nvo3] Is the cost of supporting active-active multi-homing on > a per L2VPN instance basis sustainable?**** > > **** > > **** > > If we don't do it as part of the standard, vendors will just implement > proprietary versions.**** > > **** > > active/passive anything is not welcomed in the datacenter anymore **** >
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