ISDN

ISDN

1. Definition

ISDN(integrated services digital network). It is a set of CCITT/ITU standards for circuit-switched transmission of data over various media, including ordinary telephone-grade copper wire.

2. channels

It includes 2 channels:

1. B-channels carry payloads(e.g., data or voice streams)

2. D-channels carry control and signaling information

3. leves of service

There are two levels of services: the basic rate interface(BRI) and primary rate interface(PRI).

3.1 BRI

consist of two 64kbps B-channels and one 16kbps D-channel. Thus, a BRI delivers up to 128 kbps of data.

3.2 PRI

In the U.S.A, a PRI connection consists of 23 B-channels(1472 kbps total) and one 64 kbps D-channel. In Europe a PRI connection consists of 30 B-channels(1920kbps total) and 1 D-channel.

4. ref

http://searchenterprisewan.techtarget.com/definition/ISDN

https://zh.wikipedia.org/wiki/%E7%BB%BC%E5%90%88%E4%B8%9A%E5%8A%A1%E6%95%B0%E5%AD%97%E7%BD%91