Hello, I don't know if this is the appropriate list for this kind of subject, so if anyone knows another specific list, please tell me... I'm analysing several DWDM designs to implement at my city, but I'm still a bit confusing about the Metro acess design. I'm supposed to build a physical ring topology with 6 pairs of fiber with an hub-and-spoke logical topology. The ring will have about 40Km. At the HUB we'll install our point-of-presence with a MPLS equipment, and at the spokes we'll use only IP routers. We need an flexible design where we can add or remove spokes as needed with the minimum effort possible. We are planning to have, at a initial deployment, about 200 hundred spokes, and all these spokes are talking only with the HUB site. Everything should work like in an FTTH or FTTB design, no other type of transportation is allowed (wireless and copper). We can't use SONET/SDH. The solution must be only IPoDWDM or complemented with TDMoIP at the access equipment. The problem, is that all documents that I'm reading specifies that we should be worried with faults scenarios at the spokes, so that the optical network does not stops. For example, if the OADM equipment at the spoke is down, the lambda dropped at that site will be down too... Or at least, if we use a lot of lambdas, we need to keep and eye at the points where we have regenerators. We need bandwidth from 10Mbps to 1000Mbps at these spokes. My question is: Is it possible to make such a network in a way that we don't need to worry about faults (electrical or others) at the spokes? If so, how can I do this? I don't want the spokes sites interfering directly at the operation for the whole network. Thanks for your help. -- []'s Lívio Zanol Puppim