Cisco ASR 5000 series Product Overview page 588

▀ Network Deployments and Interfaces
Interface Description
Gm The reference point between the P-CSCF and the User Equipment (UE).
The Gm interface provides SIP signaling between the GGSN and the P-CSCF.
MI The reference point between the E-CSCF and Location Retrieval Function (LRF).
The MI interface is used for routing an emergency call to a Public Safety Answering Point (PSAP). The E-CSCF
interacts with the Location Retrieval Function (LRF) to identify the next hop PSAP.
Mw The reference point between the P/S-CSCF and other CSCFs.
The Mw interface provides SIP signaling between two CSCFs.
DIAMETER Interfaces
The following table provides descriptions of DIAMETER interfaces supported by the SCM in a GSM/UMTS network
deployment.
Table 83. DIAMETER Interfaces in a GSM/UMTS Network
Interface Description
Cx The reference point between the S/I-CSCF and the Home Subscriber Server (HSS).
The Cx interface is used to authenticate subscribers, provides server assignments, push user profile information from
the HSS to the S-CSCF, and, when necessary, transmit a network initiated de-registration.
Dx The reference point between the S/I-CSCF and Subscriber Location Function (SLF).
The Dx interface is used to proxy queries to a subscriber data server (such as an HSS) in which subscription data for a
user can be found. The SLF receives a query for the subscriber data server, looks up the address of appropriate
subscriber data server, and proxies the query to the appropriate subscriber data server.
Rf The reference point between the P-CSCF and the Offline Charging System (OFCS).
The Rf interface is used to transfer charging information that will not affect, in real-time, the service being rendered.
For more information, refer to the 3GPP2 specification X.S0013-007-A v1.0.
Rx The reference point between the P-CSCF/A-BG and the Charging Rule Function (CRF)/Policy Decision Point (PDP)
(PCRF).
The Rx interface (3GPP 29.211) is used to exchange Flow Based Charging (FBC) control information between the
PCRF and the P-CSCF/A-BG. The CRF uses the information to make FBC decisions that are then exchanged with the
Traffic Plane Function (TPF).
This interface is used in a 3GPP2 Release 7 implementation.
Sh The reference point between the S-CSCF and Home Subscriber Server (HSS).
The Sh interface is used for retrieval and update of call feature data parameters.
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