Session Border Controller

A Session Border Controller (short: SBC) is a network component for safe coupling of different computer networks or computer networks with different security requirements. SBC are mainly used in Voice over IP ( VoIP) networks used to connect external ( uncertain ) data networks with internal ( secure ) to tie or not to implement so-called sessions IT structures.

An SBC enables control and control over the signaling and usually also media streaming as well as construction, use and dismantling of telephone calls or other interactive media are involved in a communication.

Areas of application

An SBC is, as the name implies, used at network boundaries and coupled internal and external networks. The SBC analyzes the different data streams ( engl: sessions ) and accesses, depending on the configuration in the different data streams (in this case language or signaling data ) a. In the field of telecommunications IP ( VoIP) are transmitted separately signaling data and voice / image data.

A SIP-based phone sends the signaling data usually to the telephone system while the voice data usually are transmitted via the shortest route directly from phone to phone. By decoupling the signaling and voice data on the one hand the benefits of IP-based data networks can be exploited, on the other hand, the transmission of voice data can (better media data) are not affected by the telephone system.

Definitions

The term session refers to a communication between two parties in the context of telephony. Each call consists of one or more signaled messages ( ring patterns ) as well as media streaming components whose quality must be controlled. Together, these currents form a session. It is the job of a session border controller to influence the data streams of the sessions.

The term network boundary refers to a separation point between a part of a network and another network. A simple example of this is a local company network that is defined by a so-called firewall, from the rest of the Internet. A more complex example is a local enterprise network, which includes different departments with different security needs for its locations and data. In this case, different filtering, a router or other network elements are used to control the flow of data streams. It is the job of a Session Border Controller to support this session data across borders.

The term control relates to the influence that the session border controller of the data streams that comprise sessions, exerts at boundaries between a part of a network and to cross one another. In addition, session border controller often offer access controls and data conversions for the calls they control or control.