John Lee john at internetassociatesllc.com
Sat Aug 30 23:03:56 CDT 2008


If you are looking for optical systems my fav pub is Lightwave at http://lw.pennnet.com/. They list DWDM and CWDM systems, lasers, optics, ROADM etc. If you have nanog archives go back at least six months to the thread on DWDM vs CWDM et al that I was one of the contributors to.

The last comment you make I do not understand since:

1. DWDM systems have many more lasers / wavelengths that are used and most metro and WAN providers can supply you a ITU wavelength at the normally obscene prices.

2. CWDM systems are usually 4, 8, 16, 24 that are also on ITU wavelengths like DWDM systems but with 50 - 100 nm or more spacing so the lasers and optics do not have to be so precise as the DWDM optics.

Currently it is my understanding the 10 Gbps signals are carried on 4 x 2.5 Gbps signals that are compatible with existing CWDM and DWDM equipment. There are 40 Gbps DWDM systems and 10 Gbps lasers on 100 Gbps and greater capacity systems. I agree with Alex's comments that to have 10 Gbps on a CWDM system is to have a CWDM system of at least 40 to 100 Gbps and that is very expensive today.

John (ISDN) Lee

>From Lightwafve:

Optelian adds CWDM XFP transceivers
AUGUST 19, 2008 -- Optelian (search for (search for Optelian)) has announced the availability of new LightGAIN 10-Gbit/sec CWDM XFP transceivers, which the company claims create a cost breakthrough in 10-Gbit/sec capacity growth by combining the low price points of CWDM with the inventory cost benefits of using MSA-compliant pluggable transceivers.
"These new CWDM XFP transceivers are a cost-saving solution for fiber-constrained customers looking to grow their 10-Gbit/sec services [but] who don't need the full migration path provided by DWDM," explains Dave Dal Farra, senior Optelian product manager. "And in higher growth networks, the low first cost and inventory savings can still be taken advantage of by adding up to 9 DWDM wavelengths into unused CWDM channels, utilizing Optelian's hybrid CWDM/DWDM multiplexers and 10-Gbit/sec tunable DWDM regenerators."

The new CWDM XFP transceivers are fully supported and backwards compatible in LightGAIN 6140, 5140, and 3060 systems, plugging into the existing RGN-10GXF 10-Gbit/sec regenerator card. As part of LightGAIN, the flexibility of CWDM pluggable transceivers combines with Optelian's Quick-Turn Custom Passives so that custom 10-Gbit/sec CWDM configurations can be delivered as quickly as two weeks, claim company representatives.
Also useful for wavelength conversion, reach extension, and regeneration, the 10-Gbit/sec CWDM XFP transceivers are now available for order. Key specifications include coverage from 1471 nm to 1611 nm, plus SONET and Gigabit Ethernet compliance for data rates with or without G.709 FEC.

>From Alex's older e-mail:

On Fri, 25 Apr 2008, John Lee wrote:
> Subscribe to Lightwave (at no charge) and look at the back issues for networks. Show up at Supercom or OFC or what is replacing them and get the latest on ROADM, full channel tunable lasers and maintenance costs.
> What size of network do you want to grow to before replacing the optical link equipment including ILAs?
> Most any org can cost justify a CWDM / CAN since you can add one fiber pair at a time and one lambda per fiber pair.
> DWDM gear is much more expensive and is aimed at 20 to 40 lambdas per
> fiber for service providers while UDWDM and ULHWAN are aimed at trans
> oceanic links and are very very expensive.
DWDM gear is not expensive. Passive muxes cost little. Active
transceivers cost money but not very expensive at all.
Check out these two presentations (by yours truly et al):

From: Zed Usser [zzuser at yahoo.com]
Sent: Saturday, August 30, 2008 2:54 PM
To: nanog at merit.edu
Subject: 10GE CWDM


I seem to suffer from an acute lack of 10GE CWDM optics options. Is it just me or am I just looking in all the wrong places?

You'd think that by now there would be an upgrade market from 1GE to 10GE. DWDM wavelenghts are not always available, but CWDM often are.

- Zed

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