Black-box 5000 User Manual download pdf (Page 79)

CHAPTER 8: Link Configuration

8.7 The X.21 Link

INTRODUCTION TO X.21

Unlike the mux links (leased-line links), which are

permanently connected, X.21 is a pay-as-you-go link.

When a signal is raised, the network automatically

establishes the link to the remote side. When you

are finished, the link is dropped until it is again

needed. The link is established on demand. X.21 is

for data-only channels; it does not support voice or

fax channels. In X.21 link operation, the

Multiserver must be connected (via the PTT-

provided line terminator) to a feeder mux (not

another Multiserver).

This X.21 application (X.21 bis) is designed for

Automatic Direct Call across an X.21 bis network.

Automatic Direct Call means that any data or signal

(DTR) activity on any Multiserver channel

configured for X.21 applications causes the

Multiserver to signal the network to initiate a call.

Only one call route is required. Calls initiated

locally and remotely (at the mux end) have the

capacity to switch and contend for resources on the

Multiserver.

ORT CONFIGURATION FOR THE X.21 LINK

Select option 5 on the Port Configuration Menu.

A clocking message will not display; X.21 clocking is

provided externally. You will be returned to the

Configure Local Nodes Menu.

Important

The Multiserver must be node-reset (to

current configuration) after the port

has been configured for an X.21 link.

CONFIGURATION OF X.21 LINK PARAMETERS

After configuring the port for an X.21 link, the

X.21 link parameters must be set. Select option 14

(X.21 Link Parameters) of the Configure Local

Nodes Menu.

You will be prompted:

If the port is not configured as X.21, you will receive

an error message:

** NOT X.21 LINK **

Most likely, a node reset was not done after the port

was configured for the X.21 link. Do a node reset

and access this menu again.

The X.21 Link Parameters Menu then appears (see

next page). Each of the menu options is discussed

in detail in Table 8-2.

After the X.21 Link Parameters are configured,

perform a link reset. (See Section 11.1, Reset, and

Table 11-1, Reset Options, for further information.)

After resetting, the Multiserver will exchange

information with the feeder mux and,

approximately 20 seconds later, the link will drop

until an X.21 call is initiated.

The CCM indicator lights do not reflect the X.21

link status. The Command Facility Node Status

display will show the link status (see Section 8.8,

Review Link Configuration).

CONFIGURE LOCAL NODES [node id]

X.21 LINK PARAMETERS

ENTER NODE-ID/CHANNEL #

(^X TO ABORT):

PORT CONFIGURATION [xxx]

X.21 LINK

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Black-box 5000 User Manual Page 79

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