Operating Manual
KE3500
xDSL
M
ULTI
T
EST
published in 2007 through 2011. VDSL2 permits the transmission of asymmetric and symmetric aggregate
data rates up to 200 Mbit/s downstream and upstream on twisted pairs using a bandwidth up to 30 MHz. It
deteriorates quickly from a theoretical maximum of 250 Mbit/s at source to 100 Mbit/s at 0.5 km and 50 Mbit/s at
1 km, but degrades at a much slower rate from there, and outperforms VDSL.
VLAN
A Virtual Local Area Network (VLAN) is a logical subnet within a switch or an entire physical network. It may
extend over one or more switches. A VLAN separates physical networks into subnets by ensuring that VLAN-
compatible switches do not relay the frames (data packets) of one VLAN into another VLAN and this even
though the subnets can be connected to common switches. Tagged VLANs involve networks that use network
packets bearing additional VLAN identification marks. Tagging in VLANs is also used if the VLANs extend, for
example, over several switches, say, via trunk ports. In this case, the frames bear an identification mark that
indicates association with the appropriate VLAN.
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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