In a ring topology network it may happen that the communication to an NE is lost even if the direct fiber connection path between the NE and the GNE is not down.
Taking as start point the newtork in the attached file (three sites: A, B and C), it may happen that the communication is broken for two NEs (for example site B and C) even if the only physical link which is down is the one between site A and B.
Check if there are line cards not configured in the NE (maybe because not used).
If there are, configure the board (add the corresponding line card in the NE layout configuration panel).
Check in the "DCC management" panel (DCC configuration and DCC resource allocation tabs) whether there are now new line cards configured to handle the DCC bytes.
If there are some new ones, disable the DCC allocation related to the boards that are not used (the ones that were not configured). This will allow you to free the not necessary DCC bytes and use them for the desired line unit (i.e.: the line card interconnecting the multiplex section between A and C).
Then remove again the not used line cards from the NE layout panel and try to login again into the NE.
Going into the "DCC management" section (NE explore panel), one can see that the communication status for the corresponding port (i.e: the line card handling the connection between A and C sites) is wrong, and the DCC bytes cannot be processed. Even if trying to allocate the DCC bytes to the right line card used, in the "DCC Resource Allocation" tab, the operation has no success.
This may happen if there are some boards physically installed in the subrack but not used, hence not configured. This is mainly because this cards are occupying lot of DCC bytes and the maximum number of DCC bytes handled by the SCC board is 120.