Logical Interfaces - Cisco ASR 5000 Series Administration Manual

Understanding the Service Operation

Logical Interfaces

This section describes the logical interface supported on HNB-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 HNB-GW service, it will function as an Iuh interface between the
SeGW (HNB-GW) service and the HNB. Services are defined later in this section.
In support of both mobile and network originated subscriber UE contexts, the HNB-GW provides the following network
interface support:
Iuh Interface: This interface is the reference point for the control plane protocol between Home NodeB and
HNB-GW. Iuh uses SCTP over IPSec IKEv2 tunnel as the transport layer protocol for guaranteed delivery of
signaling messages between HNB-GW and Home NodeB.
This is the interface used by the HNB-GW to communicate with HNB on the same Femtocell Access Network.
This interface serves as path for establishing and maintaining subscriber UE contexts.
One or more Iuh interfaces can be configured per system context.
IuCS: This interface is the reference point in UMTS which links the HNB-GW, which acts as an RNC (Radio
Network Controller), with a Mobile Switching Centre (3G MSC) in the 3G UMTS Femtocell Access Network..
This interface provides an IuCS over IP or IuCS over ATM (IP over AAL5 over ATM) interface between the
MSC and the RNC (HNB-GW) in the 3G UMTS Femtocell Access Network. RAN Application Part (RANAP)
is the control protocol that sets up the data plane (GTP-U) between these nodes. SIGTRAN (M3UA/SCTP) or
QSAAL (MTP3B/QSAAL) handle IuCS (control) for the HNB-GW.
This is the interface used by the HNB-GW to communicate with 3G MSC on the same Public Land Mobile
Network (PLMN). This interface serves as path for establishing and maintaining the CS access for Femtocell
UE to circuit switched UMTS core networks
One or more IuCS interfaces can be configured per system context.
IuPS: This interface is the reference point between HNB-GW and SGSN. This interface provides an IuPS over
IP or IuPS over ATM (IP over AAL5 over ATM) interface between the SGSN and the RNC (HNB-GW) in the
3G UMTS Femtocell Access Network. RAN Application Part (RANAP) is the control protocol that sets up the
data plane (GTP-U) between these nodes. SIGTRAN (M3UA/SCTP) or QSAAL (MTP3B/QSAAL) handle Iu-
PS-C (control) for the HNB-GW.
This is the interface used by the HNB-GW to communicate with SGSN on the same Public Land Mobile
Network (PLMN). This interface serves as path for establishing and maintaining the PS access for Femtocell
UE to packet switched UMTS core networks.
One or more Iu-PS interfaces can be configured per system context.
Gi: This interface is the reference point between HNB-GW and IP Offload Gateway. It is used by the HNB-GW
to communicate with Packet Data Networks (PDNs) through IP Offload Gateway in the H-PLMN/V-PLMN.
Examples of PDNs are the Internet or corporate intranets.
One or more Gi interfaces can be configured per system context.
Gn: This interface is the reference point between HNB-GW and GGSN. It is used by the HNB-GW to
communicate with GGSNs on the same GPRS/UMTS Public Land Mobile Network (PLMN).
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