Chapter 1 Dcc Configuration; Overview; Introduction To Dcc; Dcc Configuration Methods - 3Com 3C13636 Configuration Manual

3Com Router 3000 Ethernet Family
Configuration Guide

Chapter 1 DCC Configuration

1.1 Overview

1.1.1 Introduction to DCC

I. DCC
Dial control center (DCC) is a routing technology for routers interconnected through a
public switched network: public switched telephone network (PSTN) or integrated
services digital network (ISDN). It can provide the dial-on-demand service whereby a
router dials to set up a connection only when there is data to be transferred. When a link
becomes idle, DCC automatically disconnects it.
Under certain circumstances, connections between routers are instantly established
whenever there is data to be transferred, so the data transfer is characterized by
no-time-correlation, outburst and small data amount. DCC provides a flexible,
economical and efficient solution for such applications. In practice, DCC guarantees
the priority of communications through designated backup lines. In the case that a
primary line for normal communications becomes unavailable for any reasons, DCC
uses the designated backup channels to carry out the communications to assure that
the required services are timely completed.
At present, Frame Relay network is widely applied. Usually, the user accesses Frame
Relay network through the leased line. To reduce the cost, the user can adopt Frame
Relay over ISDN technology to access the Frame Relay network through ISDN line.
Meanwhile, ISDN network can act as the backup of Frame Relay access.
II. Terms in DCC configuration
Physical interface: Physical interface that actually exists, like the serial, BRI,
asynchronous interfaces.
Dialer interface: Logical interface for configuring DCC parameters. A physical
interface can inherit the DCC configuration after it is bound to the dialer interface.
Dial interface: A general term describing an interface for dialup connection. It can
be a dialer interface, a physical interface bound to the dialer interface, or a
physical interface directly configured with DCC parameters.

1.1.2 DCC Configuration Methods

V 2.41 provides two DCC configuration methods: circular DCC (C-DCC), and
resource-shared DCC (RS-DCC). With distinguishing features, these two methods are
applicable to different applications. In applications, the participating ends of a call can
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Chapter 1 DCC Configuration