In my experience in leasing dark fiber strands over long distance the providers usually give the option for regen colo space. And in some cases they wanted to know full specs of the equipment you are going to be using so there is no questions if it will work or not. Carlos Alcantar Race Telecommunications, Inc. 101 Haskins Way South San Francisco, CA 94080 P: 650.649.3550 x143 F: 650.649.3551 E: carlos@race.com -----Original Message----- From: Mike [mailto:mike-nanog@tiedyenetworks.com] Sent: Friday, January 01, 2010 2:53 PM To: nanog@nanog.org Subject: dark fiber and sfp distance limitations I am looking at the possibility of leasing a ~70 mile run of fiber. I don't have access to any mid point section for regeneration purposes, and so I am wondering what the chances that a 120km rated SFP would be able to light the path and provide stable connectivity. There are a lot of unknowns including # of splices, condition of the cable, or the actual dispersion index or other properties (until we actually get closer to leasing it). Its spare telco fibers in the same cable binder they are using interoffice transport, but there are regen huts along the way so it works for them but may not for us, and 'finding out' is potentially expensive. How would someone experienced go about determining the feasibillity of this concept and what options might there be? Replies online or off would be appreciated. Thanks.