Operating Manual
KE3600
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VOD
Video-on-demand describes the possibility of downloading digital video material from an Internet provider or
service upon demand or to view the material directly by way of a video stream using suitable software. For the
video stream, reception in real time, a high-speed broadband Internet service via cable or DSL (at least 6000
kb per second for optimal video quality) is necessary. An Internet rate with unlimited data (data flat rate) is an
advantage because this creates a large amount of data traffic.
VoIP
IP Telephony (short for Internet Protocol telephony) also known as Internet Telephony or Voice over IP (VoIP
for short) is telephoning over computer networks built according to Internet standards. In this respect,
information typical for telephoning, that is, voice and control information, for example for initiating the
connection, is transferred by way of a network also useful for data transmission. Computers, telephone
terminals specialized for IP telephony and classic telephones connected by way of special adapters can
initiate the connection between the call participants.
VPI/VCI
ATM is based on connections that may either be permanent or only switched for a specific time by means of
ISDN-like signaling. Virtual Paths (VPs) and Virtual Channels (VCs) are defined for this purpose. The header of
each ATM cell contains a Virtual Path Identifier (VPI, 8 or 12 bits) and a Virtual Channel Identifier (VCI, 16 bits).
As these cells pass through the ATM network, switching is achieved by changing the VPI/VCI values. Although
the VPI/VCI values do not necessarily remain the same from one end of the line to the other, this corresponds
to the concept of a line because all packets with the same VPI/VCI values take the same path. This is in
contrast to IP where one packet might reach its destination using a different route than the preceding and
following packets. Virtual lines have the advantage that they can be used as a multiplexing layer for different
services (voice, Frame Relay, IP, SNA, etc.) that can then divide one common ATM connection without causing
mutual interference.
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KURTH ELECTRONIC www.kurthelectronic.de [email protected]
