The topology is a ring network created for testing purposes.
The ring has 3 nodes.
One OSN3500 -the GNE-, and two OSN 2500.
The ring was configured with 2f MS-SPRing at STM-16 level.
In order to check that the protection configuration works, we unpluged the fibre connecting the OSN 3500 and one OSN 2500. Yet instead of switching we lost communication with the NE's.
The alarms on T2000 were: NE_NOT_LOGIN and NE_COMMU_BREAK.
It is known that the SCC card has a handling capability of 40 DCC channels. D1-D3 is a 3-byte channel, while D4-D12 is a 9-byte channel.
From T2000-Function tree-Communication-DCC management-DCC Rate Configuration it was found out that the DCC resources were not enough. The DCC communication configuration of the node has exceeded the restriction of the DCC communication capability of the SCC What was done was to close or adjust the DCC communication of some optical interfaces as needed. Then the alarm was cleared and the switching was perfomed.
Since we lost communication with the NE's and according to experience the problem was thought to be in the SCC card.
DCC resources must always be checked and unused optical interfaces must be closed do as to have enough DCC resources.