[120743] in North American Network Operators' Group
Re: dark fiber and sfp distance limitations
daemon@ATHENA.MIT.EDU (Richard A Steenbergen)
Fri Jan 1 18:20:15 2010
Date: Fri, 1 Jan 2010 17:19:30 -0600
From: Richard A Steenbergen <ras@e-gerbil.net>
To: Mike <mike-nanog@tiedyenetworks.com>
In-Reply-To: <4B3E7CB1.2090608@tiedyenetworks.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Fri, Jan 01, 2010 at 02:52:33PM -0800, 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.
That shouldn't be too difficult, especially at only 1G (though pesonally
I can't imagine why you would bother leasing dark fiber for that :P).
There are several ways you could do it, including 120km+ rated SFPs
(iirc there have been 200km SFPs out for a while too), an external
optical amplifier (ideally you'd want to amp in the middle, but with a
single channel you should be fine w/pre-amp), and a digital FEC wrapper
to extend the receive sensitivity. Remember that the distance spec on
optics is mostly a rough guideline, so depending on the fiber conditions
and number of splices/panels along the way you could potentially expect
to get the entire distance out of a "standard" 100km optic.
--
Richard A Steenbergen <ras@e-gerbil.net> http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)
