dark fiber and sfp distance limitations

Fri Jan 1 23:19:08 UTC 2010

On Fri, 1 Jan 2010, Mike wrote:

> 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.

The first thing you need to do is test the fiber with an OTDR.  If you 
don't have one, you can probably contract a local cabling company to test 
it for you.

How do you plan to drive transport over the fiber?  GE?  10G?  >10G? 
CWDM?  DWDM?

To drive a signal that far without a regen somewhere in the middle, your 
best bet might be something in the xWDM space, and then you can provision 
labmdas for GE, 10G, etc...  There are boxes out there (Ciena, Infinera, 
Cisco ONS, etc) that can do this.

How do you plan to handle responses to fiber cuts, signal degradation, 
someone at $telco unplugging the wrong jumper, etc?

jms