Overview

FortiOS Carrier provides all the features found on FortiGate units plus added features specific to carrier networks:

MMS and GTP.

MMS

MMS is a standard for sending messages that include multimedia content between mobile phones. MMS is also

popular as a method of delivering news and entertainment content including videos, pictures, and text. Carrier networks include four different MMS types of messages — MM1, MM3, MM4, and MM7. See “MMS background”.

GTP

The GPRS Tunneling Protocol (GTP) runs on GPRS carrier networks. GPRS is a GSM packet radio standard. It provides more efficient usage of the radio interface so that mobile devices can share the same radio channel. FortiOS supports GTPv1 and GTPv2.

GPRS provides direct connections to the Internet (TCP/IP) and X.25 networks for point-to-point services (connection-less/connection oriented) and point-to-multipoint services (broadcast).

GPRS currently supports data rates from 9.6 kbps to more than 100 kbps, and it is best suited for burst forms of traffic. GPRS involves both radio and wired components. The mobile phone sends the message to a base station

 

Registering FortiOS Carrier

unit (radio based) that converts the message from radio to wired, and sends the message to the carrier network and eventually the Internet (wired carrier network). See GTP basic concepts.

Registering FortiOS Carrier

A license is purchased from Fortinet, and is delivered by mail as a scratch card. The contained registration code is entered into the CLI according to the instructions on the card. The FortiGate unit will then factory reset itself into Carrier mode.

Only certain FortiGate models support Carrier mode. Contact Fortinet Support for more information and firmware images.

MMS background

MMS is a common method for mobile users to send and receive multimedia content. A Carrier network supports MMS across its network. This makes up the MMS Service Provider Network (MSPN).

Messages can be sent or received between the MMSC and a number of other services including the Internet, content providers, or other carriers. Each of these different service connections uses different MMS formats including MM1 and MM7 messages (essentially HTTP format), and MM3 and MM4 messages (SMTP formatted).

These different formats reflect the different purposes and content for each type of MMS message.

MMS background

MMS content interfaces

MMS content interfaces

MMS messages are sent from devices and servers to other devices and servers using MMS content interfaces

There are eight interfaces defined for the MMS standard, referred to as MM1 through MM8. The most important of these interfaces for the transfer of data is the MM1 interface, as this defines how mobile users communicate from the mobile network to the Multimedia Message Service Center (MMSC). MMS content to be monitored and controlled comes from these mobile users and is going to the provider network.

Other MMS content interfaces that connect a service provider network to other external sources can pose threats as well. MM3 handles communication between the Internet and the MMSC and is a possible source of viruses and other content problems from the Internet. MM4 handles communication between different content provider MMSCs. Filtering MM4 content protects the service provider network from content sent from foriegn service providers and their subscribers. Finally MM7 is used for communication between content providers and the MMSC. Filtering MM3 content can also keep harmful content off of the service provider network.

MMS background

MMS content interfaces

Type	Transaction	Similar to
MM 1	Handset to MMSC	HTTP
MM 3	Between MMSC and Internet	SMTP
MM 4	Between Operator MMSCs	SMTP
MM 7	Content Providers to MMSC	HTTP and SOAP

How MMS content interfaces are applied

As shownbelow, the sender’s mobile device encodes the MMS content in a form similar to MIME email message (MMS MIME content formats are defined by the MMS Message Encapsulation specification). The encoded message is then forwarded to the service provider’s MMSC. Communication between the sending device and the MMSC uses the MM1 content interface. The MM1 content interface establishes a connection and sends an MM1 send request (m-send.req) message that contains the MMS message. The MMSC processes this request and sends back an MM1 send confirmation (m-send.conf) HTTP response indicating the status of the message — accepted or an error occurred, for example.