CCNA Complete Guide 2nd Edition.pdf - Cisco Learning Home

- ISDN offers very fast call setup than analog modem dialup connections, which may take 30 – 60
seconds. ISDN circuits can be established in a second or two.
- Below lists the B and D channels on ISDN BRI and PRI:
Interface Type
Number of Bearer
(B) Channels
Number of Signaling
(D) Channels
Descriptive Term
BRI 2 (64kbps) 1 (16kbps) 2B+D
T1 PRI (1.544Mbps) 23 (64kbps) 1 (64kbps) 23B+D
E1 PRI (2.048Mbps) 30 (64kbps) 1 (64kbps) 30B+D
Note: E1 PRIs are being used in most parts of the world.
BRI
PRI
2B
Figure 26-2: The B and D Channels on ISDN BRI and PRI
- Below lists the ITU-T ISDN standards and protocols:
Dealing With Protocols Key Examples
ISDN on existing E-series E.163 – International telephone numbering plan
telephone network
E.164 – International ISDN addressing
ISDN concepts, aspects,
interfaces, and services
D
23B or 30B
D
I-series I.100 series – Concepts, structures, and terminology
I.400 series – User-Network Interface (UNI)
Switching and signaling Q-series Q.921 – Link Access Procedure – D Channel (LAPD)
Q.931 – ISDN network layer between terminal and
ISDN switch (SS7, DSS1)
- Below lists the ISDN I-Series and Q-Series specifications:
Layer as in
OSI Model
I-Series
Equivalent Q-Series
Specification
Description
3 ITU-T I.450 ITU-T Q.930 Defines ISDN signaling messages – call
ITU-T I.451 ITU-T Q.931 setup and termination messages. Ex: SS7.
2 ITU-T I.440
ITU-T I.441
1 ITU-T I.430
ITU-T I.431
ITU-T Q.920
ITU-T Q.921
–
–
NT1
CSU/DSU
188
Service Provider Network
Defines the LAPD protocol used on the D
channel for encapsulating and ensures
the delivery of the signaling information.
Defines connectors, encoding, framing,
and reference points.
Tips: From the 2nd digit of a standard, Q-series matches OSI Layers. For I-Series, minus 2.
Note: The ISDN D signaling channel comprises of the functionalities of Layer 1 to 3 of the OSI
reference model.
- ISDN standards were published by International Telecommunications Union Telecommunication
Standardization Sector (ITU-T).
Copyright © 2008 Yap Chin Hoong
yapchinhoong@hotmail.com