THOMSON SpeedTouch, Руководство по настройке

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Chapter 1
Introduction
E-DOC-CTC-20051017-0167 v1.0
5
1.1.3 Connection Services
Concept
As part of the DSL service provisioning, the ISP configures a connection service at
the remote end of each virtual channel.
Connectivity to the Internet or a company’s Intranet is by far the most important
service offered by an ISP. For practical realization though, some adjustments must
be made. For example the BRAS enforces the use of a certain frame format on the
virtual channel. Another important aspect is how the connection is bootstrapped
(always-on / dial-up) and how IP settings like IP address, default gateway and DNS
servers are configured at the local end.
All these items can be collectively referred to as connection service and consist of:
a connection service name
the virtual channel identifier
the connection service type
the ATM encapsulation type
Whether a connection is always-on or dial-up and the way IP configuration is
accomplished in the remote end, is mostly implied in the
connection service name .
For example PPPoE is native dial-up and IP configuration happens via PPP-IPCP.
Each ISP has its own policy for assigning connection services to virtual channel(s).
1.1.4 Packet Services
Function
The main function of a packet service is to forward frames or packets between the
DSL line and the SpeedTouch™ LAN ports and vice versa. Therefore the connection
service offered on the DSL line must be “attached” to the appropriate packet
service in the SpeedTouch™.
Concept
The concept of packet services refers to:
The type of packet or frame that is expected on the virtual channel
The type of filtering/forwarding function that handles the frame/packet at the
local end
The pre- and post-processing steps that are applied on a per frame/packet
basis
Whether a connection is “dial-in” or is inherently “always-on”
Whether frame/packet processing is done completely in the SpeedTouch™, or
partially in the SpeedTouch™ and partially in the attached PCs
Whether the connection can be shared or not
The way parameters like IP addresses are negotiated, etc.