3Com 3C63400-3AC-C - PathBuilder S700 Switch Reference Manual page 123

Figure 76 CBR Reference Clock Selection menu
e Select the option corresponding to the card and slot number you want to
designate as the clock source to open the reference clock port selection menu.
This menu lists all the In Service ports on the selected card.
f Select the option corresponding to the port you want to designate as the clock
source.
g Return to the System Clock Configuration menu.
h Repeat steps 2a-2g for up to seven additional clock sources (you can set up to
eight), substituting the appropriate option ([4] -[10]) for [3] Set PriorityClock 1
in step a.
If priority clock #1 fails, priority clock #2 becomes operative; if priority clock #2
fails, priority clock #3 becomes operative, and so on. For a list of the alarm
conditions which cause a clock source to fail, see Table 31 later in this section.
3 Select [1] Set Clock Mode, and set the clock mode to one of the following:
Revertive—If priority clock #1 fails, and priority clock #2 or higher becomes
operative, the system reverts to priority clock #1 if this clock source becomes valid
again within the specified Revertive Time (see step 4),
Non-Revertive—If priority clock #1 fails, and priority clock #2 or higher becomes
operative, the system does not revert to priority clock #1 after it becomes valid
again.
In non-revertive mode only, you can manually switch to priority clock source
#1—or the highest valid clock source. To do this, select [11] Set SysClk to Highest
Priority from the System Clock Configuration menu.
4 (revertive mode only) Select [2] Set Revertive Time and specify the length of time
(10-900 seconds) the system will monitor priority clock #1 before either reverting
to it (if the clock source becomes valid again) or continuing to use a lower priority
clock source.
Viewing and Configuring System Information 109