Alcatel Carrier Internetworking Solutions Omni Switch/Router - Manual (Page 979)

Page 32-1
32 Managing ISDN Ports
The WAN Switching Module for the Basic Rate Interface (WSX-BRI) supports 1 or 2 Universal
Serial Ports (USP) and 1 or 2 ISDN Basic Rate Interfaces (BRI). The USPs can support Frame
Relay or Point-to-Point Protocol (PPP). The BRI interface can support only PPP.
The Universal Serial Port on a WSX-BRI board is operationally identical to the USPs found on
the 4- or 8-port WSX-S board. The ISDN BRI port is an RJ-45 connector. The BRI port can be
configured either as a “U” interface for the North American market or as an “S/T” interface for
international markets. The WSX-BRI board also supports hardware data compression via the
STAC 9705 Data Compression Coprocessor.
The ISDN BRI interface supports switched connections, usually through a central office
switch. Connections can be established when data is available for a remote peer, referred to
as “demand” mode, or when a primary circuit is inactive, referred to as “backup” mode.
Overview of ISDN
Integrated Services Digital Network (ISDN) is a switched network that incorporates a digital
connection to the central office (the local loop), instead of the current telephone network’s
analog connection. Because the worldwide telephone network is becoming increasingly digi-
tal in the trunks between switching centers, the incorporation of ISDN allows for end-to-end
switched digital connections. In general, there are three main goals for ISDN:
• provide end-to-end digital connectivity
• support a wide range of services, both voice and non-voice
• access the ISDN by a limited set of standard user-to-network interfaces
Basic Rate Interface (BRI) Versus Primary Rate Interface (PRI)
There are two methods defined for accessing ISDN. The Basic Rate Access (BRA) method,
commonly known as the Basic Rate Interface (BRI), was intended for residential subscribers
and small offices. The Primary Rate Access (PRA) method, commonly known as the Primary
Rate Interface (PRI), was intended for users with greater data-transfer capacity requirements,
such as offices with a digital PBX. The Omni Switch/Router WSX-BRI board supports only the
BRI interface. Future products may be introduced that include support for PRI interfaces.
The WSX-BRI interface terminates at an ISDN-capable switch in the central telephone office.
In order to perform properly, the WSX-BRI board must know to which type of telephone
switch it is being connected. You must provide your Omni Switch/Router with this informa-
tion during configuration of the WSX-BRI board. Also, depending upon the type of telephone
switch you will be accessing, you may need to obtain from the telephone company a Service
Profile Identification (SPID). The SPID is used in North America for DMS100, ATT 5ESS and
Nation ISDN 1switch types.