Swyx SwyxConnect 1722, Руководство пользователя

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Introduction 1-1
1 Introduction
Swyx VoIP Routers are fully functional routers with an integrated
firewall to provide local networks with secure access to the Internet.
With the VPN option included, these devices work as powerful
Dynamic VPN gateways for external locations or mobile users.
Along with the ADSL connection, these devices also feature ISDN
connections, and some feature analog telephone connections. An
ISDN line can be used to backup the WAN connection, for remote
management of the router, as a basis for office communications via
LANCAPI, and for establishing Dynamic VPN connections to
external locations that use dynamic IP addresses.
By using the Voice over IP function, these devices can transfer voice
data over broadband Internet as well as over ISDN and analog
telephone connections.
1.1 How do ADSL and ADSL 2+ work?
ADSL (Asymmetric Digital Subscriber Line) is currently the most
common technology for broadband Internet connections. Standard
and almost ubiquitous telephone lines (analog or DSL) are the basis
for DSL data transfer to the nearest telephone exchange. From here,
the data is passed directly on to the Internet over high-speed
connections.
The asymmetric DSL variant ADSL was developed for applications
where users receive large amounts of data but transmit only small
amounts, such as when surfing in the WWW. ADSL subscribers can
receive data at up to 8 Mbps ("downstream") and transmit at up to
800 kbps ("upstream"). ADSL providers are able to reduce these
maximum rates as they please.
To satisfy the strongly increasing demand for higher bandwidths, the
standards ADSL 2 and ADSL 2+ provider higher data rates as a basis
for applications such as video streaming or high-definition TV
(HDTV) over the Internet. Depending on the Internet provider,
ADSL 2 devices support downstream data rates of up to 12 Mbps,
and ADSL 2+ devices support up to 24 Mbps. Handshake routines
during connection establishment ensure that the standards ADSL,
ADSL 2 and ADSL 2+ are intercompatible.
Parallel to data transfer, ADSL also provides full and unlimited
support for the classic applications in telephony (telephone, fax,