Terminology; Contexts - Cisco ASR 5000 Series Administration Manual

▀ Terminology

Terminology
This section defines some of the terms used in the chapters that follow.

Contexts

A context is a logical grouping or mapping of configuration parameters that pertain to various physical ports, logical IP
interfaces, and services. A context can be thought of as a virtual private network (VPN).
The system supports the configuration of multiple contexts. Each is configured and operates independently from the
others. Once a context has been created, administrative users can then configure services, logical IP interfaces,
subscribers, etc.for that context. Administrative users would then bind the logical interfaces to physical ports.
Contexts can also be assigned domain aliases, wherein if a subscriber‟s domain name matches one of the configured
alias names for that context, then that context is used.
Contexts on the system can be categorized as follows:
Source context: Also referred to as the "ingress" context, this context provides the subscriber‟s point-of-entry in
the system. It is also the context in which services are configured. For example, in a GPRS/UMTS network, the
radio network containing the Service GPRS Support Nodes (SGSNs) would communicate with the system via
Gn interfaces configured within the source context as part of the GGSN service.
Destination context: Also referred to as the "egress" context, this context is where a subscriber is provided
services (such as access to the Internet) as defined by access point name (APN) configuration templates. For
example, the system‟s destination context would be configured with the interfaces facilitating subscriber data
traffic to/from the Internet, a VPN, or other PDN.
Authentication context: This context provides authentication functionality for subscriber PDP contexts and/or
administrative user sessions and contains the policies and logical interfaces for communicating with Remote
Authentication Dial In User Service (RADIUS) authentication servers.
For subscriber authentication, this functionality must be configured in the same system context as the APN template(s).
Optionally, to simplify the configuration process, both subscriber RADIUS authentication functionality and APN
templates can be configured in the destination context.
Important:
configured in the local context.
For administrative users, authentication functionality can either be configured in the local context or be authenticated in
the same context as subscribers.
Accounting context: This context provides accounting functionality for subscriber PDP contexts and/or
administrative user sessions.
▄ Cisco ASR 5000 Series Gateway GPRS Support Node Administration Guide
To ensure scalability, authentication functionality for subscriber sessions should not be
Understanding the Service Operation
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