GGSN (Gateway GPRS Support Node)

GGSN (Gateway GSN, Gateway GSN) basically is an Gateway function, it can and different kinds of data network connection, such as ISDN, PSPDN and LAN, etc. Some literature, the GGSN called GPRS router. GGSN can put the GSM network packets on the GPRS grouping protocol conversion, thus can take the grouping packet transmission to a remote TCP/IP or x.25 network.

GPRS networks and networks outside boundaries, the internal network transmission, responsible for guide foreign is an Internet router. One of the BGGSN (Border GGSN) is responsible for the connection between the different operators guide network, realize the nets between roaming. GGSN based on IP protocol of GPRS backbone with other GGSN and SGSN connected

The main function

1) network access control function

GGSN with network control information shielding function, can choose what grouping can enter the GPRS networks, to ensure the safety of GPRS networks,

GGSN has billing information collection function, can collect each MS practical external data networks and GPRS networks resource related G_CDR billing info.

2) maintenance routing table, realize routing and packet forwarding function

GGSN has store-and-forward function, and from a node receives the packet data (PDP units = pdus) transmitted to routing next node functions.

GGSN has simultaneously to PDP units = pdus sorting function. GGSN should guarantee GGSN and MS transmitted between the PDP units = pdus the largest size of 15 bytes, from external data networks to received more than the above requirements shall be determined according to the GGSN units = pdus PDP, PDP types and concrete implementation of its segmented, discarded or refuse.

GGSN has PDP context activation, PDP context modification, PDP context to activate function;

GGSN has address translation and mapping function, including search DNS, realize DNS function;

GGSN has encapsulation and tunnel transmission function, can will come from external data networks with the PDP units = pdus GTP injured-dedicated with TCP/IP or UDP/IP injured-dedicated conducted by the function, and repacking the injured-dedicated the evil in related address information as the logo, GPRS backbone, using a peer-to-peer two-way tunnel to transmit data encapsulation. To sending to external data networks, the PDP units = pdus GGSN will remove the encapsulation injured-dedicated again after transmitted to external data networks.

3) the user data management, and to realize the packet data filtering

GGSN can store, modification and deletion user data, and to realize the user group data filtering.

4) mobility management functions

GGSN can match with SGSN realized mobility management function, main is MS in different SGSN login location management functions.

5) other function

GGSN for MS has the function of dynamic assign IP addresses, or can through the access DHCP (dynamic host configuration protocol) server to realize dynamic assign IP address function;

GGSN has access RADIUS (remote authorized dialed users service) server realize user authentication function.