BinTec X4000, Руководство пользователя

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X4000 User’s Guide 485
Glossary
V.90 ITU standard for 56 kbps analog modems. In contrast to older V.34 modems,
data is sent in digital form to the client when the V.90 standard is used and does
not need to be first converted from digital to analog on one side of the modem
(provider), as was the case with V.34 and earlier modems. This makes higher
transmission rates possible. A maximum speed of 56 kbps can be achieved
only under optimum conditions.
VDSL Very high bit rate
➤➤
Digital Subscriber Line (also called VADSL or BDSL).
The data rate is 1.5 to 2.3 Mbps
➤➤
upstream and 13 to 52 Mbps
➤➤
downstream over ranges of 300 m to 14 km.
The main VDSL applications are: as for
➤➤
ADSL , but at higher transmission
rates and with synchronization over short ranges.
VJHC Van Jacobson Header Compression
➤➤
data compression procedure for IP header compression.
VPN Virtual Private Network
The use of existing structures such as the
➤➤
Internet structure for
connecting private networks (e.g. SOHO exchange). The data can be encrypted
between the two endpoints of the VPN to meet increased security requirements.
WAN Wide Area Network
Wide Area Network connections, e.g. over ISDN, X.25.
WAN interface WAN interface
WAN interfaces connect the local network to the (
➤➤
WAN ). This is usually
done by means of analog or digital telephone lines (
➤➤
switched or
➤➤
leased lines ).
WAN partner Remote station that is reached over a
➤➤
WAN , e.g. ISDN.
X.21 The X.21 recommendation defines the physical interface between two network
components in packet-switched data networks (e.g. Datex-P).
X.21bis The X.21bis recommendation defines the
➤➤
DTE /
➤➤
DCE interface to V-
series synchronous modems.