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Cisco WAN Manager User’s Guide
Version 10.5, Part Number 78-12945-01 Rev. D0, August 2003
Chapter1 1 CWM to CWM Communica tions Establishing Primary CWM and Secondary CWM Priority
Establishing Primary CWM and Secondary CWM Priority
In a given wide area network managed by Release 10 of CWM, the first CWM workstation to begin
operation will assume the role of Primary CWM. As other CWM workstati ons become active, they will
take on Secondary CWM workstation roles. The only difference in function between Primary and
Secondary CWM workstations is that the Primary CWM workstation would provide the Secondary
CWM workstations with user d ata w he n the Secondary CWM workstati on launches.
Priority numbers of all Second ar ie s ar e as sig n ed by th e P ri mar y at th e t im e a S eco n da ry regi s ters w i th
the Primary. It is based on “first-come-first-serve” logic. All the Seco nd ar ie s h ave th e s a m e privilege
except that the Secondary wi th priority 1 will take over as th e P r ima ry if the Primary shuts dow n.
The priority numbers of Second ar ie s mi gh t c ha nge in a Secondary CWMGateway p r oc es s’s lifecycl e.
In the following cases, the priority numbers among Secondary CWMGatew ays might change randomly:
•Restart the Primary CWMGateway ( by wat ch do g )
•SwitchOver due to the Pr imary shutdown
•Primary ForceSwitchOver to a Second ar y
This is the result of re-registr at io n w i th th e n ew Primary CWMGateway process. P ri or i ty nu m b er s w ill
be re-assigned by the new Primary C W M Ga teway p r oc ess w h en a S eco ndar y r egi ster s w i th th e new
Primary. In other words, for whatever reas on t he P rim a ry C W M G atewa y p r oc ess c ha ng es, the priority
numbers of the Secondaries wil l be sub j ect to r e- ass i gn me nt.
It is possible that an S2 (Se condary with Priority 2) ca n become an S1 after the P rimary CWMGateway
is restarted (by watchd o g) . It is a lso possible that an S3 can become an S1 aft er the switchover.
In the following cases, the priorit y nu mb er s am ong Secondary CWMGateways w ill N OT ch an ge
randomly:
•Restart a Secondary (by watchdog)
•Shutdown Secondary
In these cases, if Sn (Secondary with priority n) is restarted or shutdown, any Sm (m>n) will become
S(m-1), while any Sm (m<n ) w ill r em a in as S m.
The difference between these scenar io s i s th at in a S hutd ow n Seco nd ar y ca s e, th e P rim ary
CWMGateway process did not change.
Re-establishing Priority after CWM-CWM Communications have been Interrupted

Primary CWM Graceful S hutdown

The first CWM to be launched assumes the role of the primary by default. Subsequently, other CWMs
launched will register with the pri mar y CW M an d eac h S ec on d ar y C W M is as si gned a priority number
which identifies the order in which the Secondary CWM was launched with respect to the primary
CWM. Before being shutdown gracefully by the user, the CWMGateway on the primary CWM will
invoke the IDL interface (used to comm un ic ate between two CWMGateway process es), of each of the
objects corresponding to a Secondary CWMGateway. This will notify the Secondary CWM that the
primary CWM is about to go away and that it will in turn n ominate the second CWM in line (priority 1)