Elements Of An Isdn Connection; The Local Loop - HP ProCurve Secure 7000dl Series Basic Management And Configuration Manual

Elements of an ISDN Connection

All WAN connections, including ISDN lines, consist of three basic elements:
the physical transmission media, such as the cabling, switches, routers,
and other infrastructure required to create and maintain the connection
electrical signaling specifications for generating, transmitting, and receiv-
ing signals through the various transmission media
Data Link Layer protocols, which provide logical flow control for trans-
mitting data between the two WAN peers (devices at either a connection)
Physical transmission media and electrical specifications are part of the
Physical Layer (Layer 1) of the Open Systems Interconnection (OSI) model,
and Data Link Layer protocols are part of the Data Link Layer (Layer 2). (See
Figure 8-1.)
7 Application Layer
Presentation Layer
6
5 Session Layer
Transport Layer
4
Network Layer
3
2 Data Link Layer
Physical Layer
1
Figure 8-1. Physical and Data Link Layers of the OSI Model
When you configure an ISDN WAN connection, you must configure both the
Physical Layer and the Data Link Layer (which is also called the Logical Layer).

The Local Loop

Like other WAN technologies, ISDN connections are provided through public
carrier networks. When you lease an ISDN line, your company's equipment
must be connected to your public carrier's nearest central office (CO). All of
the telecommunications infrastructure—such as repeaters, switches, cable,
and connectors—that connects a subscriber's premises to the CO is referred
to as the local loop.
Configuring Demand Routing for Primary ISDN Modules
Overview of ISDN Connections
PPP
HDLC
ATM
Frame Relay
ISDN
8-5