Cisco IOS XE, Configuration Manual, Page: 42 / 358

Overview of ISG
Information About ISG
6
Benefits of ISG
ISG provides the following benefits:
•
A common system for session management across Cisco products and access technologies. New
access protocols, forwarding protocols, and features may be plugged in with minimal impact and
maximum potential for reuse.
• Separation of the concerns of subscriber identification, service application, and subscriber access
and session type.
•
Flexible session definitions.
• Flexible session detection.
•
Flexible, iterative approach to identification, service activation, and policy activation.
• Different trust levels. Session authorization is not contingent on authentication.
•
Control policies. Control policies facilitate distributed policy decision-making, reducing round-trip
latency between the edge device and policy server, and allow system event handling to be described
in a consistent and intuitive manner.
• Common policy model and language for control and traffic policy.
•
Provision for dynamic policy updates via CoA (through service activation or “policy push”).
• Use of existing Cisco IOS infrastructure to provide session functionality.
•
Use of existing Cisco IOS infrastructure to track session state and life cycle.
• Creation of a session context at first instance of subscriber interaction, thereby facilitating the
immediate application of policy to subscriber traffic.
•
Flexible distribution of service data.
• Range of accounting options, including prepaid accounting, postpaid accounting, tariff switching
for prepaid and postpaid accounting, interim accounting, event-based accounting, and flow-based
accounting.
•
Single sign-on services to an external application.
• Flexible infrastructure in support of “equal-access” deployments, such as service-based Dynamic
Host Configuration Protocol (DHCP) pool and DHCP server determination, dynamic readdressing
through DHCP, and VRF transfer.
•
Support for standard external interfaces, such as RADIUS and CoA.
Planning for ISG Implementation
ISG is very flexible and supports a wide variety of functionality. Before you begin to configure ISG, you
should plan your system carefully. The following sections describe some of the important aspects of your
system that you should consider:
•
Trust Model, page 7
• Subscriber Access Model, page 7
•
Single Sign-On Requirements, page 7
• Network Forwarding, page 7
•
Service Packaging, page 8
• Billing Model, page 8