Nexus 7k with DWDM back to back link for pre-stage testing

[aacole]

Am planning a pre-stage of a pair of Nexus 7K switches with DWDM optics fitted, as the final solution is to connect over an existing ONS.

Question is, for the pre-stage lab test is there any reason why I cannot back to back the N7k's by connecting the DWDM optics together using a suitable LC terminated cross-over fibre cable? Works fine for standard MM and SM interfaces, but have never used DWDM before, so am calling on those with experience of this technology.

[Tom Randstrom · Accepted solution]

You can install them back to back with DWDM transceivers but it requires the installation of a 10dB attenuator for each fiber link.  This is because the output power of the DWDM is -1 to +3dBm and the receiver's input range starts at -7dBm.  Thus, without the attenuator to lower the light power, the light level would be greater than the optical receiver's lower operating limit (-7 to -23dBm), which can cause errors on the link.     

[aacole]

Thanks Tom for quick reply.