The window size of the control tunnel
History Tables.
The control tunnel history table is implemented as
a sliding window in which at most the last
'cisgIpsSgHistTableSize' entries are maintained.
This object is, hence, used to control the size of
the tunnel history table.
An implementation may choose suitable values for this
element based on the available resources.
If an SNMP SET request specifies a value outside this
window for this element, in appropriate SNMP error
code should be returned.
Setting this value to zero is equivalent to deleting
all conceptual rows in the archiving table
('cisgIpsSgTunnelHistTable') and disabling the
archiving of entries in the tables.