nanog mailing list archives
Re: Advice/Experience with small sized DDWM gear
From: "N. Richard Solis" <nrsolis () aol net>
Date: Thu, 7 Aug 2003 17:14:58 -0400
Fletcher, My primary responsibility here is engineering exactly these kinds of systems. The biggest difference between CWDM systems and DWDM systems is system reach. Most CWDM systems are designed for short haul applications like yours (approx 20km and under. Most DWDM systems are designed for much more expansive requirements (50-600km). The primary reason for this is amplification and laser power. CWDM systems use low power uncooled lasers that can drift in frequency making it hard for them to pack many channels into the limited transmission window provided by available fiber. Amplifiers will raise the system cost. DWDM systems use higher power lasers that are actively cooled to make them stable in frequency and consequently, you can fit more into the transmission window. They get system reach by using optical amplifiers. I've had great experience with several vendors but ultimately your choice depends on your particular situation and requirements. CWDM will be much lower cost. Look at the ONLINE 2500 series from Ciena or the CWDM options from Movaz Networks. But don't stop there. There are MANY other CWDM vendors that can help you. Don't forget to check what kinds of channel bandwidths are supported. Some can provide actual BER information for each muxed channel. If you have further questions, don't hesitate to contact me. fkittred () gwi net wrote:
On Fri, 20 Jun 2003 14:56:41 -0400 "Deepak Jain" wrote:Nanogers, We are looking for advice/experience from folks who has used small6-8Wavelength DDWM. Also what are the pros and cons of CDWM and DDWM? Application; 5 Mile Dark Fiber between two carrier neutral hotelsin SF.All help is appreciated and results will be shared if requested.Arman, I think the biggest difference between small DWDM and CWDM ishow muchgrowth room you need. If you need 8 wavelengths (possibly 16 is still called CWDMbut I doubtit) you can stay on the CWDM side. The lasers and the gear is generallycheaper.With DWDM gear everything seems to be more expensive, but youget a lotmore control as the electronics governing the chassis' tend to bemuch moreadvanced. On a short run like that, many advanced features likeall-opticalamplification and such are not necessary. I am not aware of anyall-opticalCWDM amplifiers yet. (for example). If you are planning more than just 1 DF run, you could buy thelessexpensive solution and just swap it out when you need something moreand usethe CWDM solution somewhere else. If you have decent/modern fiber, you should be able tocomfortable signal 8 waves x 1G or 8 x 2.5G (full duplex). Some DWDM gear will let youdoublethat on just 8 colors by going full duplex on each fiber (each thread). So its a question of how much BW you need and how much youwant to payfor right now. (If I am wrong, someone please correct me). Hope this helps, let me know what you decide.I would be interested in recommendations for specific hardware. We are looking at longer runs and the units must be NEBS compliant as the nodes are in telco COs. thanks, fletcher
Current thread:
- Re: Advice/Experience with small sized DDWM gear fkittred (Aug 07)
- Re: Advice/Experience with small sized DDWM gear N. Richard Solis (Aug 07)