Chapter 7: Signaling Plane

Overview

In a complex and distributed network architecture such as GPRS, some exchanges of information are required between the various nodes in order to control and support the transmission plane functions within the network. The necessary information used to coordinate the various nodes is called the signaling information. It is structured into messages.

This chapter covers the signaling related to mobility aspects and external packet network access. The focus in this chapter is on the signaling plane between the MS and the SGSN, and between the GSNs. The signaling related to RR management and the Gb interface are covered in Chapters 5 and 6, respectively.

One of the fundamental services in a GPRS network is mobility management. This must take into account functions such as access to GPRS services, paging for routing of incoming packet-switched calls, security, and location change of the GPRS subscriber. These functions are described in Section 7.1.

The signaling related to PDP context management enables the handling of access to an external packet-switching network via a GGSN. Routing information and QoS attributes characterize the PDP context and are negotiated during PDP context procedures. Section 7.2 describes PDP context management within the GPRS network.

The signaling between GSNs provides functions such as path management between two GSNs, tunnel management between an SGSN and a GGSN, location management between a GGSN and an GSN having an SS7 interface, and mobility management between two SGSNs. These functions are provided by the GTP protocol in the control plane and are described in Section 7.3.