Bri Isdn - HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual

BRI ISDN

BRI ISDN operates over the twisted-pair cabling that is used for ordinary
telephones. All of the telecommunications infrastructure that is used to
connect your LAN to the CO is collectively called the local loop.
The local loop is divided into two sections by a line of demarcation (demarc),
which separates your company's wiring and equipment from the public car-
rier's wiring and equipment. (See Figure 3-1.) As a general rule, your company
owns, operates, and maintains the wiring and equipment on its side of the
demarc, and the public carrier owns, operates, and maintains the wiring and
equipment on its side of the demarc. For ISDN connections, the position of
the demarc varies, depending on which ISDN equipment the public carrier
provides.
Demarc (outside
North America)
TEI
(Router)
Terminal
TE2
adapter
R
interface interface
Figure 3-1. ISDN Network
In addition to the demarc, the local loop includes:
(North America)
NT2 NT1
S T
interface interface
ISDN switch—At the public carrier's CO, the ISDN switch multiplexes and
de-multiplexes channels on the twisted pair wiring of the local loop. It
provides the physical and electrical termination for the ISDN line and then
forwards the data onto the public carrier's network.
Repeater—A repeater receives, amplifies, and retransmits the digital
signal so that the signal is always strong enough to be read. Because ISDN
lines use 2B1Q coding, which operates at a lower frequency range than
T1 or E1 encoding, repeaters are required only every 5.49 km (18,000 feet).
In contrast, T1 encoding requires a repeater approximately every 1.6 km
(1 mile or 5,280 feet).
Configuring Backup WAN Connections
Backing Up Primary WAN Connections
Demarc
Network
Interface Unit
(Smart Jack)
U
Public
Wire span
Carrier's CO
ISDN
Repeater
Switch
ISDN Switch
3-7