NEC Univerge sv8500 Manual page 236

(c) When PRIMARY IP-BS starts running by itself due to not find CS for the synchronization.
IP-BS assigned as PRIMARY will search for the CS in the following order:
(1) CS having SYS-ID specified as clock source
(2) CS which has identical SYS-ID and whose synchronization has been established
If IP-BS is unable to find CS using all of the above, it starts running by itself while searching for CS of the spec-
ified SYS-ID, IP-BS will synchronize the CS as soon as the search is successful.
Secondary
SUB-PRIMARY
SYNC
VOL.1-176
CHAPTER 3 INSTALLATION DESIGN
PRIMARY
SYNC
Internal
PHE