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    Overview of GGSN and P-GW

    The Juniper Networks MobileNext Broadband Gateway can act as a gateway GPRS support node (GGSN) in a 2G and 3G network architecture, a Packet Data Network Gateway (P-GW) in a 4G/LTE network architecture, or even both at the same time. When it comes to user traffic, the differences are mainly in the terms used to refer to the “mobile-facing” side of the gateway and not the IP data side.

    Figure 1 shows the major components and interfaces of a mobile network based on 4G/LTE standards.

    Figure 1: 4G/LTE Mobile Network Basic Components

    4G/LTE Mobile Network Basic Components

    The major components are:

    • User equipment (UE)—Often called the “mobile platform” in other standards. The user equipment can be a mobile smartphone, a “dongle” used to enable service on another device, a laptop, or even other compliant devices.
    • RAN (Radio Access Network)—The RAN is called the universal terrestrial radio access network (UTRAN) in the 3G Universal Mobile Telecommunications System (UMTS) architecture (sometimes UTRAN is defined as UMTS Terrestrial Radio Access Network). In the LTE architecture, the RAN is the evolved UTRAN, or E-UTRAN.
    • S-GW—In the LTE architecture, the node that handles all signaling messages to and from the user equipment is called the Serving Gateway (S-GW). (The SGSN in 3G networks is different from the S-GW in 4G networks.).
    • P-GW—In 2G and 3G networks, the node that handled all user packets to and from the user equipment is called the GGSN. In the LTE architecture, this is the Packet Gateway (P-GW) or sometimes seen as the Packet Data Network Gateway (PDN-GW).
    • IP Cloud– This is the Packet Data Network (PDN) in 2G and 3G and LTE. However, LTE adds another type of IP network, called IP Multimedia Services (IMS). IMS networks essentially handle VoIP calls to and from the user equipment.

    From the GGSN/P-GW perspective, the major interfaces in the figure are:

    • S5—In 4G/LTE, the S5 interface connects the P-GW to the mobile side of the network (for home users). In 3G, this is the Gn (“n” for network) interface.
    • Gi/SGi—In 4G/LTE, the SGi interface connects the P-GW to the IP packet side of the network. In 3G, this is the Gi (“i” for Internet or IP network) interface.

    Published: 2011-11-16