NEs managing connection

HI  

as you description there should have at least two network  DWDM(OSN 8800) and MSTP( OSN3500 )。

1，In DWDM(OSN8800) network there's OCS(ST/AST/SC board ) which is the communication channel  between GNE and NE.

2, In MSTP(OSN 3500) network there's ECC(SDH board) which is the communication channel between GNE and NE.

3,The  NMS can directly connection with the GNE(gateway NE).

4,In the case which you have normally we will make two GNE. one for MSTP and another one for DWDM as the following picture.

 

5，For power system management because you are not mention what is the interface.

So i can just give the suggestion is :

Create E1 or Eth service from site A to the other three sites through OSN3500 equipment,then management all of power system by these links 

Hi
In site A you have NE , this NE is the gateway for other NEs .
For 8800 the NE in site A is the gareway for 8800
For OSN 3500 the NE in site A is the gareway for OSN3500.
so you should configure them as gareways in the U2000.
and to define these NEs as gateways for other NEs also in the U2000.
in site A u simply should connect the Management Ethernet port of NEs in site A to a switch or router then to the U2000 server .

For powering systems they usually dont come with ethernet port for controling but they come with alarm output port this port can be connected to OSN3500 alarm in ports .
This will not provide controling for the powering systems but can show you alarm indication on U2000.
I hope to be useful for u .
Regards