On 06/04/13 21:50, Thomas Weible - FLEXOPTIX wrote:
Matt Addison [mailto:matt.addison@lists.evilgeni.us] wrote:
How much spare margin do you have? Could you roll your own with a pair of mismatched (C|D)WDM XFPs and a mux on each end?
Typically you have 23dB powerbudget for the ZR (CWDM or DWDM) - maybe +2 dB through selection of TOSA. A CWDM Mux will take 2dB and a small DWDM Mux approx. 4dB - you need two of them. This will drag your overall link-powerbudget below 20dB.
It might work if you add a FEC (either on the linecard or the XFP itself). This will add approx. 5dB to your powerbudget of 23dB. Take a CWDM Mux and fire x-crossed on 1550 and 1570 (maybe 1530) and you will face an attenuation of approx. 0,2 - 0,25dB/km. This could work and you should be able to transmit 80km to 90km. It's worth a test - also to figure out if dispersion will have an impact or not.
If you're going to that effort buy a mux with an amp, and use short-haul SFP's with FEC. A choice I found particularly neat (I got a hold of some of their HW architecture docs but haven't actually tried it) is the SmartOptics "m:series", an 4/8/16/32ch PTP metro DWDM system in a 1ru box (or 2ru for 8/32ch) http://www.smartoptics.com/products/mseries/ MRV, BTI and others make more modular options if you want just the EDFA's.