BinTec X4000, Руководство пользователя

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X4000 User’s Guide 155
Configuring WAN Interfaces
7
7.2.3 Configuring the LAN Interface for Using ADSL
(PPP-over-Ethernet)
ADSL To be able to use ADSL (Asymmetric Digital Subscriber Line) with X4000 , you
must configure a PPP-over-Ethernet interface over the LAN interface. This is
done by connecting X4000 to T-DSL, which is the ADSL connection of
Deutsche Telekom AG.
T-DSL The T-DSL package is currently offered by Deutsche Telekom AG as high-
speed access to the Internet. It consists of an ISDN connection and a data line
with a bandwidth of up to 768 kbps from the Internet Service Provider to the
customer (downstream) and 128 kbps in the upstream direction.
Security risks and
restrictions
If you use the ADSL connection of another provider, ask the provider about any
special features of your ADSL connection that need to be observed.
The following restrictions and security risks exist as the X4000 connection to T-
DSL is established only over one Ethernet interface:
■
If PPP-over-Ethernet is operated with only one Ethernet interface, there is
a risk of unauthorized accesses from the Internet to the local X4000 LAN.
Such unauthorized accesses can originate from the first node of the
Internet.
■
Users of the local network can configure a PPP-over-Ethernet client on their
PC and use the Internet unnoticed by X4000 .
■
Broadcasts in the local LAN are always forwarded by the ADSL modem
(NTBBA) to the PTT exchange and are not rejected until the exchange. This
means that the maximum bandwidth of 128 kbps upstream to the PTT
may not be fully available.
The limitations and security risks described here do not apply if X4000 is
equipped with a LAN expansion card and several LAN interfaces are therefore
available (see
chapter 9.3.2, page 288 ).