General RADIUS Configurations Configuration Guide, Cisco IOS XE Release 3S
Offload Server Accounting Enhancement
Offload Server Accounting Enhancement
Last Updated: March 25, 2013
The Offload Server Accounting Enhancement feature allows users to maintain authentication and accounting information between their network access servers (NASs) and the offload server.
Although NASs can already synchronize information with an offload server, this feature extends the functionality to include a unique session-id, adding the Acct-Session-Id (attribute 44) before the existing session-id (NAS-IP-Address), and Class (attribute 25) information collected by the NASs.
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Before configuring the Offload Server Accounting Enhancement feature, you must perform the following tasks:
Information About Offload Server Accounting Enhancement
The Offload Server Accounting Enhancement feature allows users to configure their network access servers (NAS) to synchronize authentication and accounting information--NAS-IP-Address (attribute 4) and Class (attribute 25)--with the offload server.
An offload server interacts with a NAS through a Virtual Private Network (VPN) to perform required Point-to-Point Protocol (PPP) negotiation for calls. The NAS performs call preauthentication, whereas the offload server performs user authentication. T his feature allows the authentication and accounting data of the NAS to synchronize with the offload server as follows:
How to Configure the Offload Server Accounting Enhancement
Configuring Unique Session IDs
To maintain unique session IDs among NASs, use the following global configuration command. When multiple NASs are being processed by one offload server, this feature must be enabled by all NASs and by the offload server to ensure a common and unique session-id.
Configuring Offload Server to Synchronize with NAS Clients
To configure the offload server to synchronize accounting session information with the NAS clients, use the following global configuration command:
Verifying Offload Server Accounting
To verify whether the NAS has synchronized authentication and accounting data with the offload server, use the following commands in privileged EXEC mode:
Configuration Examples for the Offload Server Accounting Enhancement
Unique Session ID Configuration Example
Feature Information for Offload Server Accounting Enhancement
AAA --authentication, authorization, and accounting. Suite of network security services that provide the primary framework through which access control can be set up on your Cisco router or access server.
Acct-Session-ID (attribute 44) --A unique accounting identifier that makes it easy to match start and stop records in a log file. Acct-Session ID numbers restart at 1 each time the router is power-cycled or the software is reloaded.
Class (attribute 25) --An accounting attribute. Arbitrary value that the network access server includes in all accounting packets for this user if the attribute is supplied by the RADIUS server.
L2F --Layer 2 Forwarding. A Layer 2 tunneling protocol that enables an ISP or other access service to create a virtual tunnel to link customer remote sites or remote users with corporate home networks. In particular, a network access server (NAS) at the ISP point of presence (POP) exchanges PPP messages with the remote users and communicates by L2F or L2TP requests and responses with the customer tunnel server to set up tunnels.
NAS --network access server. A Cisco platform (or collection of platforms, such as an AccessPath system) that interfaces between the packet world (for example, the Internet) and the circuit world (for example, the public switched telephone network).
NAS-IP Address (attribute 4) --Specifies the IP address of the network access server that is requesting authentication. The default value is 0.0.0.0/0.
PPP --Point-to-Point Protocol. Successor to SLIP that provides router-to-router and host-to-network connections over synchronous and asynchronous circuits. Whereas SLIP was designed to work with IP, PPP was designed to work with several network layer protocols, such as IP, IPX, and ARA. PPP also has built-in security mechanisms, such as CHAP and PAP. PPP relies on two protocols: LCP and NCP.
RADIUS --Remote Authentication Dial-In User Service. RADIUS is a distributed client/server system that secures networks against unauthorized access. In the Cisco implementation, RADIUS clients run on Cisco routers and send authentication requests to a central RADIUS server that contains all user authentication and network service access information.
VPN --A system that permits dial-in networks to exist remotely to home networks, while giving the appearance of being directly connected. VPNs use L2TP and L2F to terminate the Layer 2 and higher parts of the network connection at the LNS instead of the LAC.
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Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.
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