Terminology - Cisco ASR 5000 Administration Manual

System Operation and Configuration
Important

Terminology

This section defines important terms used throughout this guide.
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 context is configured and operates
independently of the others. Once a context has been created, administrative users can configure services,
logical IP interfaces, and subscribers for that context and then bind the logical interfaces to physical ports.
You can also assign a domain alias to a context; if a subscriber's domain name matches one of the configured
alias names for a context, that context is used.
Ports
Ports are the physical connectors on line cards that support remote access and subscriber traffic. Port
configuration includes traffic profiles, data encapsulation methods, media type, and other information for
physical connectivity between the system and the rest of the network.
Ports are identified by the chassis slot number for the line card, followed by the physical connector number.
For example, Port 24/1 identifies connector number 1 on the SPIO card in slot 24.
Associate ports with contexts through bindings. For additional information on bindings, refer to the Bindings
section below. You can configure each physical port to support multiple logical IP interfaces, each with up
to 17 IP addresses (one primary and up to 16 secondaries).
For complete information on line cards and port assignments, refer to the ASR 5000 Installation Guide.
Logical Interfaces
You must associate a port with a StarOS virtual circuit or tunnel called a logical interface before the port can
allow the flow of user data.Within StarOS, a logical interface is a named interface associated with a virtual
router instance that provides higher-layer protocol transport, such as Layer 3 IP addressing. Interfaces are
configured as part of VPN contexts and are independent from the physical ports that will be used to bridge
the virtual interfaces to the network.
Logical interfaces are associated with ethernet+ppp+tunnel addresses and are bound to a specific port during
the configuration process. Logical interfaces are also associated with services through bindings. Services are
bound to an IP address that is configured for a particular logical interface. When associated, the interface
takes on the characteristics of the functions enabled by the service.
By default StarOS supports local Console access to the CLI via the RS-232 Console port for initial system
configuration.
ASR 5000 System Administration Guide, StarOS Release 21.1
Terminology
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