Hi Rob,
This feature is currently not supported on 5.1.
Features Not Supported
The following features are not supported in ACS 5.1:
-->Integration with SQL DB via ODBC, for external authentication and identity information.
-->TACACS+ Proxy.
-->Application access control for CiscoWorks applications.
-->Network access restriction to users whose Windows accounts have Windows dial-in permission.
-->IP Pools Server feature.
-->Support for defining the maximum number of simultaneous sessions for a user or user group.
Regards,
~JG
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