The value of vRtrPimNgAFGenBSRExpiryTime indicates the minimum
time remaining before the elected bootstrap router will be
declared down if the value of vRtrPimNgAFGenBSRState
is not 'electedBSR'.
The value of vRtrPimNgAFGenBSRExpiryTime indicates the time
remaining before the router sends the next Bootstrap Message(BSM)
if the value of vRtrPimNgAFGenBSRState is 'electedBSR'.