we've been implement DWDM ring consist of 4 nodes ONS15454SDH (ver 7.2) and recently we've added a new DWDM ROADM consist of 5 nodes (ver. 8.51).
currently we're using CTM 8.0 to monitor existing ONS ver 7.2, but with new added nodes ver 8.51, we'll have to upgrade existing CTM8.0 to CTM8.5
1. we've using CTM server 8.0 to monitor and report traffic for our clients and vital because we don't have any other NMS for Cisco DWDM.
2. upgrading CTM8.0 to CTM8.5 will need downtime, correct me if i'm wrong!
this will make us lost NMS data reported to our client which is avoided.
1. which one is better, upgrade the NMS server or trying to downgrade Cisco ONS 8.51 to 8.0 software version? (if it's possible)
2. if i'm gonna upgrade NMS CTM8.0 to CTM8.5, is there any issue with bugs , etc?
as you know last time when I upgrade NMS from CTM 7.2 to 8.0, I got bugs which i can't restore my database after upgrade the NMS server. this make us to create an incident report and apologize to our client for losing our NMS database about nine-month periode.
No you cannot import 8.0 database to 8.5.
Reason is that with every major release there are always new table entries to support new features/hardware added.
It is always recommended to also Upgrade your database. If you don't care about the old data then just install a new CTM version.