From: Guyler, Rik (rguyler@shp-dayton.org)
Date: Fri Jul 28 2006 - 13:37:02 ART
There's a little more to it than that.
MM fiber has several light pathways called modes. These light pathways
within the fiber must all be used to get the maximum potential of the fiber.
This is why SX transmitters are typically LED-based, which disperse the
light across the various modes.
SM fiber has a single light pathway or mode and so the light that travels
through this type of fiber should be concentrated. Hence the reason why LX
transmitters typically use lasers, which do not disperse light very much and
can concentrate most of the light directly on the single mode. Because the
light is concentrated and not dispersed, it will suffer much less
attenuation and result in much greater distances.
Using an LX transmitter with MM fiber can work for short distances (this
will vary due to fiber and termination quality, number of cross connects,
etc.) but because you are not able to light up all of the modes, this
combination will suffer from attentuation significantly compared to matching
them up correctly. Fiber mode conditioning cables were developed as a
middle ground, allowing the use of an LX transmitter on much cheaper (or
pre-existing) MM fiber. The conditioning cable is a MM patch cable with a
splice of SM cable on the transmit side so it receives the full capability
of the LX transmitter. The cable then distributes the LX output over the
multiple modes of the MM fiber so you get the best of both worlds: a less
expensive fiber cable plant but better distance numbers than you get with SX
tranmistters.
Rik
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Skinner, Stephen
Sent: Friday, July 28, 2006 8:30 AM
To: Cacca Mucca; Cisco certification
Subject: RE: Running SFP LX/LH over MM Fibers
What wavelength are you using
Multimode simply means the cable is cable of running a wavelength of either
850 or 1300 or whatever.
It is the circuit packs at either end which dictate what Wave your at.
Are you running this on a circuit or back-to-back
If its back to back , then aslong as your GBIC/SPF's match you will be ok .
If it's running over a circuit then it depends on how the provider puts the
circuit.
If its an 850 length circuit and you put LH gbic at either end , your cisco
switch won't work.
HTH
Stephen Skinner
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]
Sent: 28 July 2006 13:09
To: Cisco certification; Cisco certification
Subject: Running SFP LX/LH over MM Fibers
*** WARNING : This message originates from the Internet ***
Just want to confirm, I have none to test with, that I'll be able to run
LX/LH on multimode fibers.
Thanks
This archive was generated by hypermail 2.1.4 : Tue Aug 01 2006 - 07:13:48 ART