Two NE40 are ISIS neighbor. Once the ISIS neighbor relationship fails, there is no information on failure in log of both flash and hard disk of NE40. It is hard to tell when the neighbor fails, which is not good for location of failure.
Configure the log-peer-change command in ISIS mode of NE40, and the information on changes to ISIS neighbor will be recorded into the log.
In the ISIS mode of NE40, the log-peer-change command to record the status of ISIS neighbor is not configured, so there is no such information in the log of both flash and hard disk of NE40.
For the equipment that enables ISIS, it is required to configure log-peer-change command in ISIS mode. So once the neighbor relationship fails,we could know the time, good for locating the problem.