Terminology; Contexts; Logical Interfaces - Cisco ASR 5x00 Home eNodeB 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.
In HeNB-GW service implementation, the contexts can not be classified into source or destination contexts. This is
because GTP-U tunnels as well as HeNB-GW Access and Network services can be created over a single context.
The IP addresses as well as interfaces can also under the defined under the same context. These IP addresses are later
used to bind with different services including GTP-U, MME and Interfaces including S1-MME for HeNB-GW Access
service and Network service.

Logical Interfaces

This section describes the logical interface supported on HeNB-GW.
Prior to allowing the flow of user data, the port must be associated with a virtual circuit or tunnel called a logical
interface. A logical interface within the system is defined as the logical assignment of a virtual router instance that
provides higher-layer protocol transport, such as Layer 3 IP addressing. Interfaces are configured as part of the VPN
context and are independent from the physical port that will be used to bridge the virtual interfaces to the network.
Logical interfaces are assigned to IP 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. For example, if an interface is bound to an HeNB-GW service, it will function as an S1-MME interface between
the HeNB-GW/SeGW service and MME. Services are defined later in this section.
In support of both mobile and network originated subscriber UE contexts, the HeNB-GW provides the following
network interface support:
 S1 Interface: This interface is the reference point for the control plane protocol between Home eNodeB and
HeNB-GW. This interface sets up S1AP association over SCTP as the transport layer protocol for guaranteed
delivery of signaling messages between HeNB-GW and Home eNodeB.
This is the interface used by the HeNB-GW to communicate with HeNBs on the same Femtocell Access
Network. This interface serves as path for establishing and maintaining subscriber UE contexts.
 S1-MME Interface: This interface is the reference point for the control plane protocol between E-UTRAN and
MME in the LTE Femtocell network.
Protocol stack architecture for the S1-MME interface has been described in the Protocol Architecture section
of the Overview chapter of this guide.
▄ Cisco ASR 5x00 Home eNodeB Gateway Administration Guide
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Understanding the Service Operation