Line Coding For Isdn Bri Connections; Isdn Data Link Layer Protocols - HP ProCurve Secure 7000dl Series Basic Management And Configuration Manual

Secure router procurve 7000dl series

Hide thumbs Also See for ProCurve Secure 7000dl Series:

Table of Contents

R Interface. The R interface is used to connect a TE2 device to the TA.

Because there are no standards for the R interface, the vendor providing the

TA determines how the TA connects to and interacts with the TE2.

Line Coding for ISDN BRI Connections

To provide higher transmission rates on ordinary telephone wire, ISDN BRI

uses a compressed encoding scheme called 2B1Q. Essentially, this transmis-

sion scheme uses four signal levels, each of which encode one quaternary

symbol. A single quaternary symbol, in turn, represents two bits.

The two encoded bits can have up to four different values, each expressed as

a different voltage level on the transmission line, as shown in Table 8-1.

2B1Q Compressed Line Encoding Scheme

Note that zero voltage is not a valid signal level.

In addition to compressing data, 2B1Q operates in full duplex mode, allowing

data to be transmitted simultaneously in both directions on the local loop.

As mentioned earlier, the signaling information used to create and maintain

ISDN connections is transmitted over the D channel. The ITU Telecommuni-

cations Standardization Sector (ITU-T) has defined two protocols for ISDN

signaling. These protocols operate at Layer 2 (Data Link Layer) and Layer 3

(Network Layer) of the OSI model:

Q.921, which is also called Link Access Procedure for D channel (LAPD)

Configuring Demand Routing for Primary ISDN Modules

Quartenary Symbol

Overview of ISDN Connections

Line Voltage

Table of Contents