[108602] in North American Network Operators' Group
Re: transcievers/amplifiers for 150 km fiber run
daemon@ATHENA.MIT.EDU (Francois Menard)
Sun Oct 12 08:39:12 2008
From: Francois Menard <francois@menards.ca>
To: Lamar Owen <lowen@pari.edu>
In-Reply-To: <200810111225.24379.lowen@pari.edu>
Date: Sun, 12 Oct 2008 08:16:19 -0400
Cc: nanog@nanog.org
Errors-To: nanog-bounces@nanog.org
or you buy some boxes from BTI Photonics that specialize into taking =20
GigE around the world...
F.
--
Fran=E7ois D. M=E9nard
francois@menards.ca
On 11-Oct-08, at 12:25 PM, Lamar Owen wrote:
> On Friday 10 October 2008 14:50:11 Fletcher Kittredge wrote:
>> We are looking to light a two strand fiber link of about 95 miles (or
>> 150km). It would be worth a lot to us not to have repeaters. We =20=
>> are
>> hoping for Gigabit Ethernet. Sonet is possible but a less =20
>> attractive
>> solution. Are there options for this sort of distance? The longest
>> current link we have is about 65 miles. I understand the =20
>> transmission
>> characteristics of the fiber will effect distance of transmission.
>
> EDFA's can extend your power budget a few dB. Chromatic dispersion =20=
> could
> still be an issue, though.
>
> Used units that had previous homes in CATV supertrunk applications =20
> should work
> well, at least for GigE; up to 120mW is easily possible (I have a =20
> few 65mW
> (18.1dBm) EDFA's that came as part of a donation). You hit the =20
> input of the
> EDFA with your ZX (1550nm) transceiver's transmit on each end, and =20
> don't look
> at the lit fiber or even a reflection of the lit fiber (IOW, wear =20
> laser
> safety goggles). And don't even think about looping the EDFA output =20=
> back
> around without many dB of attenuation.
>
> At this power level you will have to use angle polish connectors at =20=
> the EDFA
> output (the green SC/SPC or FC/APC ones) or you can burn out the =20
> pump laser
> with the reflections.
>
> You also will need to notify your carrier's tech department of the =20
> power level
> with which you're lighting that fiber, as even several km down fiber =20=
> from an
> EDFA is in Class IIIB laser territory.
>
> A bare Cisco ZX GBIC or SFP is rated to light 70km of ordinary =20
> singlemoder
> fiber, and up to 100km of either premium (low-loss) or dispersion-=20
> shifted
> (which is also low-loss) singlemode fiber. The rated output is =20
> between 0 and
> +5dBm (1 and 3.2 mW) for the ZX laser. The link budget is 23dB for =20=
> the
> standard ZX optics. With a high-gain EDFA outputting 13 more dBm of =20=
> power
> (20 times the power) you can get a link budget for loss of 36dB; =20
> which could
> increase your range 40km, on ordinary fiber.
>
> So, in a nutshell, you'd take the TX from a ZX SFP or GBIC, a few =20
> feet worth
> of jumper to an EDFA, and light the fiber (with APC connectors only) =20=
> from the
> EDFA output. You do this at both ends.
>
