The value of tmnxBsxIsaAaGrpAaSubScale specifies the set of
scaling limits that are supported with regards to the
maximum number of AA subscribers per ISA and the corresponding
policies that can be specified.
The scaling limits may be one of:
residential (0) - scaling limits for residential operation
vpn (1) - scaling limits for VPNs
mobileGateway (2) - scaling limits for operation as a mobile
gateway
tmnxBsxIsaAaGrpAaSubScale can only be set during row creation.