25.02.2013 Views

TCP/IP Tutorial and Technical Overview - IBM Redbooks

TCP/IP Tutorial and Technical Overview - IBM Redbooks

TCP/IP Tutorial and Technical Overview - IBM Redbooks

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

20.1.2 Vo<strong>IP</strong> functional components<br />

Figure 20-1 illustrates the main components of a Vo<strong>IP</strong> networking system.<br />

phone<br />

CODEC<br />

OSS<br />

Figure 20-1 Vo<strong>IP</strong> architecture<br />

Softswitch<br />

In the traditional PSTN model, a switchboard was used to connect two separate<br />

phone circuits into one contiguous line. In the Vo<strong>IP</strong> model, this can be done<br />

through software. This concept is the softswitch, <strong>and</strong> it controls connections<br />

between the circuit <strong>and</strong> packet networks in segments where end-to-end Vo<strong>IP</strong> is<br />

not yet available. The softswitch can be broken into two entities: the Call Agent<br />

<strong>and</strong> the Media Gateway.<br />

Media Gateway<br />

The Media Gateway is used to connect different physical networks in order to<br />

provide end-to-end connectivity. It functions very similarly to a typical network<br />

switch in that it can create a heterogeneous link between endpoints, regardless<br />

of the network media in between. In addition, the Media Gateway can also<br />

connect a Vo<strong>IP</strong> circuit to a PSTN circuit, allowing the use of Vo<strong>IP</strong> despite gaps in<br />

networks, or even when only one of the endpoints if Vo<strong>IP</strong> enabled. This<br />

functionality is provided transparently, <strong>and</strong> therefore users have no need to<br />

underst<strong>and</strong> or be aware of the topologies over which their communications are<br />

transferred.<br />

726 <strong>TCP</strong>/<strong>IP</strong> <strong>Tutorial</strong> <strong>and</strong> <strong>Technical</strong> <strong>Overview</strong><br />

Soft Switch<br />

<strong>IP</strong> core network<br />

Voice Stream<br />

SS7<br />

Signaling<br />

Gateway<br />

Trunk<br />

Gateway

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!