The value of tmnxDhcpSvrSubnetRebindTimer specifies
the rebind-timer (T2).
The time at which the client contacts any available server to extend the
lifetimes of the addresses or prefixes assigned to the client.
The value of this object is only meaningful when the value of
tmnxDhcpSvrSubnetAddrType is set to 'ipv6(2)'.