[j-nsp] G/E, 1000 BASE-LX on both sides shows up but not pingable

[Rafal Szarecki (WA/EPO)]

Hello,
> 
> I used to make DWDMs for Corning. I do not know of any 
> limitation of a DWDM carrying gige as long as the frequency 
> matches the port you are going into.
> 
> Can someone correct me if I am wrong? I always thought of 
> DWDMs as a very cleverly designed passive device that will 
> simply pass the light if it "fits" through the glass filters.
> 

It's not passive. The DWDM devices are active, espetially if we talk about long holes.
Altrough CWDM can be passive.

But discussion is related to transponders. The Transponder is a device which connects on one side standard optical signal e.g. SONET SMIR or SDH S.1.1 or GE-LX and com specific lambda signal on another.

Then generally 2 types of transponder exist: asynchronous and synchronous.
- Asysnc. Accept on standard side any signal which a) has specific for given transponder, standard light weight lenght, and b) the rate below some limits e.g. 2,5GHz. Then to this transponder you can connect GE or STM-1 or OC-12, or STM-16/OC-48.
Ftom information and protocol point of view this systems are bit-stream oriented and do not provide any error detection, corelation...
In corner case you can use also 2xGE mux wchich multiplex 2 GE signal fing some cind of encapsulation, and them putting them to transponder.
- Synch. Accept on standard side signal which a) has specific for given transponder, standard light weight lenght, and b) with specific fraing and rate - e.g. STM-16. This are nor expensive, less flexible but allow for error handling. Effectivly this systems gives possibility to build longer hops.

And last but nor least - on color side there are also limitation. It is harder to build system wich allow for carry 10Gbps in single lambda then this for 2.5G. The common practive is that DWDM systems are designed for 2.5 and 10 Gbps. Ther is no system below, and only fer system of 40Gbps.DWDM is too expensive at colour-lasers, cooled and stabilized, site to consume them just for 1Gbps.

The CWDM is different story. Because CWDM is limited to just 16 lambdas (DWDM is 80 or even more), quality of laser are relaxed - so, also cheapest. Then 1Gbps pe lammbda have sens.

Also for CWDM the C-band GBIC/SFP exiest. Then colour-laser (not cooled, not stabilized) are inserted directly to data equipment, and CWDM device can be realy passive peace of glass.... But then attuneatin and dispersion limit distances. This is why CWDM is used on short distances - metro.

Rafał Szarecki JNCIE

skype me <callto://Rafal_Szarecki/>