Logical Interfaces - Cisco ASR 5500 System Administration Manual

Logical Interfaces

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.
There are several types of logical interfaces to configure to support Simple and Mobile IP data applications.
These are briefly defined below.
Management Interface
This interface provides the point of attachment to the management network. The interface supports remote
access to the StarOS command line interface (CLI). It also supports event notification via the Simple Network
Management Protocol (SNMP).
Bindings
A binding is an association between elements within the system. There are two types of bindings: static and
dynamic.
Static binding is accomplished through system configuration. Static bindings associate:
• A specific logical interface (configured within a particular context) to a physical port. Once the interface
• A service to an IP address assigned to a logical interface within the same context. This allows the interface
Dynamic binding associates a subscriber to a specific egress context based on the configuration of their profile
or system parameters. This provides a higher degree of deployment flexibility, as it allows a wireless carrier
to support multiple services and facilitates seamless connections to multiple networks.
Management ports can only be bound in the local context. Traffic or subscriber ports can only be bound in a
non-local context.
Services
Configure services within a context to enable certain functionality. The following are examples of services
you can configure on the system, subject to licensing availability and platform type:
• Gateway GPRS Support Node (GGSN) services
• Serving GPRS Support Node (SGSN) Services
• Packet Data Serving Node (PDSN) services
ASR 5500 System Administration Guide, StarOS Release 21.5
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is bound, traffic can flow through the context as if it were any physically-defined circuit. Static bindings
support any encapsulation method over any interface and port type.
to take on the characteristics (that is, support the protocols) required by the service.
System Operation and Configuration