FB6602 GGSN/L2TP gateway

The FB6602 is designed to provide a simple to use GGSN to L2TP gateway for the mobile data industry. The FB6602 acts as a GGSN accepting GTPv1 tunnel requests and connecting them on to an LNS via L2TP protocol.

This allows a mobile data operator to provide internet access to mobile users using conventional ISP based L2TP equipment and routers, such as the FB6202.

The FB6602 can also provide local IP termination of GGSN tunnels with either static configuration or via RADIUS based authentication.

Linking two industries

The FB6602 is designed and tested to connect to mobile operators IP network and use GTP (GGSN Tunnelling Protocol). The protocol used within the mobile networks involves the establishment of a PDP Context with the mobile - which is very different to the way conventional ISPs operate for broadband services. ISPs use PPP over L2TP (Layer 2 Tunnelling Protocol).

By linking these two very different protocols, the FB6602 provides the crucial gateway between the very different worlds of mobile and Internet industries.

Mobile integration

The mobile operator will typically provide an interconnect with one or more IP addresses on the mobile network. They then arrange for an APN (Access Point Name) to be assigned to these IP addresses such that a SIM using that APN will create a context from the mobile network to the FireBrick FB6602.

ISP integration (layer 2 and layer 3 handover)

As the FireBrick receives each connection, it can be configured to authenticate the mobile device either locally (based on a static config) or more typically using RADIUS servers. Once authenticated the connection can either be assigned an IP address directly which can be associated with a VLAN for private layer 3 interconnects, or it can be routed to an L2TP endpoint at a remove ISP. The remote ISP then assigns an IP address which is translated to the PDP Context and passed to the mobile network.

Usage logging

The FireBrick is not normally involved in charging records from the mobile side, but provides RADIUS accounting for all connections with details of data transfer. This is recorded per connection as the connection ends and with interim updates which are normally on the hour (but can be configured to different periods).

Managing pre-paid usage

As with the normal L2TP functions on the FB6202, the FB6602 allows RADIUS control of sessions including limits of time and data transfer totals for each session. It also allows sessions to be remotely killed if needed. This allows bespoke RADIUS server configurations to manage data throughput with pre-set limits. These limits can be used to terminate the session or simply force additional interim RADIUS accounting allowing a further decision to be made.

Roaming

RADIUS authentication contains additional information on mobile network codes and SGSN IP addresses to allow roaming SIMs to be identified and metered accordingly.

Bespoke development

FireBrick have teamed up with Andrews & Arnold Ltd to provide additional consultancy and bespoke development of RADIUS servers to manage mobile data. This has allowed pre-paid mobile data services to be developed as well as complex billing systems. Please contact us for more details.

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