[147618] in North American Network Operators' Group
RE: Range using single-mode SFPs across multi-mode fiber
daemon@ATHENA.MIT.EDU (Holmes,David A)
Thu Dec 15 13:48:03 2011
From: "Holmes,David A" <dholmes@mwdh2o.com>
To: "Justin M. Streiner" <streiner@cluebyfour.org>, Keegan Holley
<keegan.holley@sungard.com>
Date: Thu, 15 Dec 2011 10:46:53 -0800
In-Reply-To: <Pine.LNX.4.64.1112150851160.1202@whammy.cluebyfour.org>
Cc: "nanog@nanog.org" <nanog@nanog.org>,
oliver rothschild <orothschild@gmail.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
The max limit for 100 base FX (100 Mbps Ethernet) is around 6600 feet. Many=
campus ductbank systems built in the 1990s when 10 and 100 Mbps Ethernet w=
ere the commodity speeds (before GiGE) used 62.5/125 MM fiber to connect bu=
ildings. It is not unusual to see long MM runs on campus facilities where 1=
00 Mbps backbones once were the fastest speeds available.
In those days, apart from longhaul telco use, singlemode fiber was usually =
only run for closed circuit TV (CCTV) use in the campus environment, and in=
places where 1990s SM was run for CCTV it can still be used for longhaul l=
aser sfps, which to me shows that SM is future proof. SM even makes sense i=
n short runs as attenuators can be placed on the send/receive strands to re=
duce the dB so the optical receiver is not saturated.
-----Original Message-----
From: Justin M. Streiner [mailto:streiner@cluebyfour.org]
Sent: Thursday, December 15, 2011 5:53 AM
To: Keegan Holley
Cc: nanog@nanog.org; oliver rothschild
Subject: Re: Range using single-mode SFPs across multi-mode fiber
On Wed, 14 Dec 2011, Keegan Holley wrote:
> 2011/12/14 oliver rothschild <orothschild@gmail.com>
> How did you end up with a MM run this long? SX optics are only rated at
> 500 meters at best. Even with mode conditioning jumpers more the 1km is =
a
> risk. I'm glad it held up during testing though. Just out of curiosity
> did you purchase dark from a provider? Is it inside of a building?
Legacy 10baseFL/100baseFX/FDDI can run fairly long distances over OM1.
In the past I've run 100baseFX over OM1 runs with multiple cross-connects,
out to about 2 km.
jms
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