The Tispan Next Generation Network

Figure 3.23: The TISPAN NGN architecture.

ETSI TISPAN has developed an architecture to provide multimedia services over fixed accesses. This architecture is called Next Generation Network (NGN) and is based on the IMS.

NGN is an access agnostic architecture able to provide IMS services to users using any type of access. This way, users can enjoy the same set of services regardless of the access they use. Therefore, TISPAN NGN achieves the much expected convergence of mobile and fixed services.

Figure 3.23 shows the TISPAN NGN architecture. The Resource and Admission Control Sub-system (RACS) handles admission control and resource reservation. The Network Attachment Sub-System (NASS) handles network level authentication and IP address provisioning.

The Core IMS is, effectively, the IMS as defined by 3GPP. Figure 3.24 shows the Core IMS architecture. TISPAN defines three nodes that are important from the IMS perspective. They are the Interconnect Border Control Function (IBCF), the Interconnect Border Gateway Function (I-BGF), and the Access Border Gateway Function (A-BGF).

The IBCF controls the I-BGF, which in on the media plane, and can perform policy control towards other networks. The IBCF can also perform the Topology Hiding Interwork Gateway (THIG) functionality, as discussed in Section 3.5.9.

The A-BGF, which is on the media plane, is controlled by the P-CSCF and behaves as an access gateway as discussed in Section 3.5.11.

Ims With Ibcf
Figure 3.24: The Core IMS architecture.
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