Chapter 9


1:

What is the scope of the I.431 and I.432 standards?

A1:

I.431 defines the Primary Rate Interface, and I.432 defines the Basic Rate Interface.

2:

Where does the name D channel come from? What are the operational speeds of the D channel for BRI and PRI?

A2:

The name D channel comes from Delta. It operates at 16 kbps for BRI and 64 kbps for PRI .

3:

What is a V-reference point in ISDN?

A3:

A V-reference point defines the interface in a Local Exchange (LE) between the Local Termination (LT) and Exchange Termination (ET).

4:

What are the important pins in a S/T interface?

A4:

3, 4, 5, and 6.

5:

What is the modulation of the ISDN U-interface?

A5:

The U-Interface uses frequency-division multiplexing and echo cancellation.

6:

What is the bit rate of the S/T interface and U-interface?

A6:

S/T interface192 kbps; U-interface160 kbps.

7:

How many INFO messages participate in the BRI's Layer 1 initialization? What does INFO0 mean?

A7:

INFO0 to INFO4; INFO0 means "no signal."

8:

Which bit in the ISDN frame indicates line activation?

A8:

The A bit set to 1 indicates the activation of the line.

9:

What makes up DLCI in ISDN? What is the length of DLCI, TE, and SAPI?

A9:

TEI and SAPI in the LAPD protocol represent the 13-bit data-link connection identifier ( DLCI ). TEI is 7 bits; SAPI is 6 bits.

10:

What are the two indicators that Layer 2 is active?

A10:

Receiving a UA message with SAPI = 0 or TEI = xxx , where xxx is not 0 or 127.

11:

What does TE = 127 mean?

A11:

TEI = 127 is a broadcast.

12:

What is the dynamic range of TEI?

A12:

TEI ranges from 64126.

13:

What does SAPI = 0 indicate ?

A13:

Call control procedure.

14:

How do you distinguish an incoming from an outgoing call?

A14:

Check the reference flag in the Q.931 message. A message of 0 is sent by the call originator, and 1 means that the message was sent by the other party.

15:

Which ISDN protocol provides information about Bearer capability. Name three basic types of Bearer capabilities.

A15:

Bearer capability is part of the format of the ISDN Q.931 protocol, which provides information for the type of the call56-kbps data, 64-kbps data, or 56-kbps voice.




Troubleshooting Remote Access Networks CCIE Professional Development
Troubleshooting Remote Access Networks (CCIE Professional Development)
ISBN: 1587050765
EAN: 2147483647
Year: 2002
Pages: 235

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