CCNA Cisco Certified Network Associate Study Guide - FTP Server

506 Chapter 10 � Wide Area Networking Protocols
ISDN Components
The components used with ISDN include functions and reference points. Figure
10.6 shows how the different types of terminal and reference points can
be used in an ISDN network.
FIGURE 10.6 ISDN functions and reference points
Non-ISDN
device (TE2)
R
TA NT1
NT1
S/T
U
ISDN
device (TE1)
ISDN switch
service
In North America, ISDN uses a two-wire connection into a home or
office. That is called a “U” reference point. The NT1 device is used to convert
the two-wire connection to a four-wire connection that is used by ISDN
phones and terminal adapters (TAs). Most routers can now be purchased
with a built-in NT1 (U) interface.
Figure 10.7 shows the different reference points and terminal equipment
that can be used with Cisco ISDN BRI interfaces.
U
S/T
Router with
built-in NT1
U