About AAA Address Allocation
IP Address Allocation is an optional feature in the AAA Server Node test case, and is designed to provide IP address allocation in a GPRS network. You can define up to 30 address pools containing either IPv4 or IPv6 addresses with the IP Pool Manager, and the virtual server will issue addresses from the pools to authenticated MNs.
AAA address allocation uses the same type of mechanisms for both RADIUS and Diameter. This topic explains the messages and attributes used with RADIUS. In a Diameter test, the corresponding Diameter messages and attributes trigger address allocation and release using the same methods as those used in a RADIUS test.
When an MN successfully authenticates with the virtual server via an Access Request message, the server returns an IP address and mask (IPv4) or prefix (IPv6) in the Access Accept message. When an IPv4 address is issued, the IP address is transmitted in the Framed-IP-Address attribute and the mask is included in the Framed-IP-Netmask attribute. When an IPv6 prefix is issued, it is transmitted in the Framed_IPv6_Prefix attribute.
The pool from which the address or prefix is selected can be explicitly specified by including the APN name in the Called-Station-Id attribute of the Access Request message, or you can define a default pool selection method.
The virtual server reserves the address or prefix until an Accounting Request - start is received and then it is assigned to the MN's session or PDP context for the duration of the accounting period. When an Accounting Request - stop is received, the address or prefix is released back to the address pool.
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NOTE: The 3GPP-Session-Stop-Indicator attribute must be included in the Accounting Request - stop to trigger the address release. |
If an Accounting Request - start is not received within the time you define, the address or prefix is released back to the address pool and can be issued to another MN.
If the virtual server is unable to issue an address or prefix, an Access Reject is returned to the NAS and the errors are reported on the IP Pool Manager and either the RADIUS or Diameter Server Authentication measurement tabs.