Eicon Networks ISDN NT1 Especificaciones descargar pdf (Pagina 10)

arrived. It is his responsibility to understand this and to take appropriate action. Normally

this will be done in software such as MLPPP.

Summary

• The D channel carries Network Services in the form of signalling. This is the way

the user maintains his relationship with the network. Each user has one and only

one D channel.

• The B channel carries Bearer Services which are the communication between two

users. A single B channel cannot connect more than two users together.

• B channels and D channels share time on the interface.

• B channels cannot be sub-divided to provide less bandwidth

• More than one B channel can be used together to provide more bandwidth

Q/A

1. What is the D channel used for?

The D Channel is used for all the call maintenance traffic, such as call setup and call disconnect.

The D channel activity occurs between an ISDN user and the ISDN network. It does not pass across the

network to the user at the other end.

The user at the other end of a call also uses a D Channel over which it conducts a separate dialogue with

the network.

The network signaling is therefore separated from the B Channel which will carry the actual call itself. This

connection does get established end-to-end between the two users.

2. Why can you not normally send data between users through the D channel?

A D channel connection is always between the user and the network, and not between the user and the user

at the other end.

For this reason, using the D channel to transmit data is not normally possible since the connection effectively

terminates at the network.

3. Why is there only one D channel in each interface?

There is only one D channel because that is all that is ever required.

The D channel only ever transmits network signaling information. Since, as far as ISDN is concerned, there

is only ever one user and only ever one network, there is no need for more than one D channel.

4. Name two significant differences between B and D channels.

There is only ever one D channel per interface, whereas there can be multiple B channels

The D channel carries network signaling; the B channel carries the call itself

A D channel connection is always between the user and the network; a B channel connection will be

between a user and any other user

5. What is the maximum number of simultaneous connections supported by a Basic Rate Interface?

Two.

There are two B channels within a Basic Rate interface, and both can be active at the any one time.

6. What is the maximum number of simultaneous connections supported by a Primary Rate Interface?

30 (or 23 in North America).

Primary Rate is supplied with either 30 (or 23) B channels and all of these can be active simultaneously.

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Eicon Networks ISDN NT1 Especificaciones Pagina 10