Eicon Networks ISDN NT1 Especificaciones descargar pdf (Pagina 8)

You have a much greater choice of protocols for the B channel since the B channel is a

neutral conduit for data of any type. You can use it to transmit any protocol you wish (eg.

SNA or PPP). However, if the network doesn't understand the protocol it cannot give you

any assistance if your call has to be delivered to a different type of network (eg. PSTN)

where data conversion is required.

B channel charateristics

• It is important to remember that ISDN channels cannot be divided up into smaller

units. Each is provided on an "all or nothing" basis.

• Two users communicating over a B channel have 64 000 bits per second available

to them. There is nothing they can do to reduce this bandwidth.

• What about the situation where the two users find that 64 000 bits per second is not

sufficient? The only solution is to add another B channel. This gives them 128 000

bits per second. They are not using a single B channel of 128 000 bits per second.

(Don't forget that the speed of a B channel is defined as 64 000 bits per second.

Anything which operates at a different speed isn't a B channel.)

• This means that they will have two parallel calls between them and the phone bill

will show two simultaneous calls.

Using 2 B channels

Imagine that you're a user communicating with someone else, using two parallel B

channels. Does the ISDN network care whether these two B channels are connecting the

same two users or if they're connecting one user with two others?

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Eicon Networks ISDN NT1 Especificaciones Pagina 8