On 10/10/2011 06:00 PM, Mack McBride wrote:
That older fiber is probably not rated at 500 Mhz Modal BW suggested by Cisco. Older fiber is usually 200 Mhz.
True, and I expect the fibers between our dorm to be no better than 200 MHz*km.
The LX4 would be a better choice (more dispersion resistant) and max distance of 300M.
We're mainly testing with LRM because I don't like the concept of WDM plus serial->parallel->serial conversion in a single transceiver. And LRM is a newer standard. No, you're right, not the most technical arguments ;)
Oh, if you look at http://www.cisco.com/en/US/prod/collateral/modules/ps5455/prod_white_paper0900aecd806b8bcb.html, that doc doesn't mention LX4 being supported on MMF with modal bandwidth < 500 MHZ*km...
Your distance limitation is probably going to be much less than the rated value if the dispersion characteristics of the fiber don't meet the spec.
Other vendors also spec LRM to work on MMF with 160 or 200 MHz*km modal bandwidth...
Of course you will still get connectivity but you will increment errors. For dorms it probably doesn't matter much. If the streaming music and video is effected by errors it will probably save you money since the students won't stream as much.
Their streaming doesn't cost us anything and we're closely monitoring the links to check if they remain error-free. We'll only run these links if they remain reliable.
We have two links under test right now; a relatively short one (somewhere between 30-50 meters) and a longer one, around 160 meters. Both perform fine and have been error free for a couple of weeks. The shorter without any mode conditioning; the longer with a mode conditioning patch cord on one side (it'd flap & run with too many errors without the MCP).
More testing to follow, but the LRM gear looks like a good solution for us. Regards, Jeroen van Ingen ICT Service Centre University of Twente, P.O.Box 217, 7500 AE Enschede, The Netherlands _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
