Information Technology Reference
In-Depth Information
Example16-1 A Sample ISDN Configuration (continued)
isdn switch-type basic-5ess
!
interface Ethernet0
ip address 172.16.141.11 255.255.255.192
!
interface Serial0
no ip address
shutdown
!
interface Serial1
no ip address
shutdown
!
interface BRI0
description phone#5553754
ip address 172.16.20.2 255.255.255.0
encapsulation ppp
dialer idle-timeout 300
dialer map ip 172.16.20.1 name 2503A broadcast 5553759
dialer-group 1
ppp authentication chap
!
no ip classless
!
dialer-list 1 protocol ip permit
!
line con 0
line aux 0
line vty 0 4
!
end
2503B#
ISDN Services
The ISDN Basic Rate Interface (BRI) service offers two B channels and one D channel (2B+D). BRI
B-channel service operates at 64 kbps and is meant to carry user data; BRI D-channel service operates
at 16 kbps and is meant to carry control and signaling information, although it can support user data
transmission under certain circumstances. The D-channel signaling protocol comprises Layers 1 through
3 of the OSI reference model. BRI also provides for framing control and other overhead, bringing its
total bit rate to 192 kbps. The BRI physical layer specification is International Telecommunication
Union-Telecommunications Standards Sector (ITU-T; formerly the Consultative Committee for
International Telegraph and Telephone [CCITT]) I.430.
ISDN Primary Rate Interface (PRI) service offers 23 B channels and one D channel in North America
and Japan, yielding a total bit rate of 1.544 Mbps (the PRI D channel runs at 64 kbps). ISDN PRI in
Europe, Australia, and other parts of the world provides 30 B plus one 64-kbps D channel and a total
interface rate of 2.048 Mbps. The PRI physical layer specification is ITU-T I.431.
