Table of Contents
Advertisement
X.25 - Field 4
Modulo 8
This bit defines the maximum number of packets that
could be sent without an acknowledgment, as deter-
mined by the size of the Nr/Ns fields. The maximum
number of packets is equal to the modulo number
minus one.
Packet Window Size
This value defines the maximum number of packets
that can be sent without an acknowledgment from the
network. Valid values are
2
through
7.
The value to
be entered is specified by the network supplier.
Link Window Size
This value defines the maximum number of I-frames
that can be sent from the controller without receiving
an acknowledgment from the network. Valid values
are
1
through
7.
X.25 - Field 5
Packet Size
This value sets the maximum numb'er of bytes that
the controller includes in a packet. This value
includes all bytes except the packet header bytes.
Virtual Circuit Type
This bit defines the type of virtual circuit used. A PVC
(permanent virtual circuit) is the X.25 network equiv-
alent of a nonswitched line. A SVC (switched virtual
circuit) is the X.25 network equivalent of a switched
line. A customer may use both a PVC and an SVC on
the same machine but not at the same time.
Flow Control
This bit is set on if the network is providing flow
control negotiation for this controller. Flow control
negotiation allows packet size and packet window
size to be changed at the time a call is placed when
using SVC. The manual options allowed bit must also
be on.
58
Control Unit Setup Procedure
Manual
Opti~ns
Allowed
This bit must be set on to allow operator entry of all
keyboard entered options except network address,
logical channel
10,
and password.
If this bit is on and the customer has only one PVC
subscription, the connection is established without
operator action as soon as the controller is powered
on and diagnostics completed. The virtual circuit
type must be set to indicate PVC only.
The following bits apply only to controllers attached
to an X.25 network via an X.21 bis interface
(EIA/ECITT communication card used in the con-
troller).
Local Loopback Supported
Remote Loopback Supported
Test Indicate Supported
These bits must be set to correspond to the informa-
tion received from the network supplier.
X.25 - Field 6
Reverse Charge
When this bit is set on, if the customer is using an
SVC with the answer option and the reverse charging
facility is included in the customers subscription,
incoming calls with reversed charging will be
accepted.
LLC Selection
This value determines the type of LLC (logical link
control) that will be used by the controller.
Special Network Attachment
This bit sets up the controller to operate on the UK
PSS X.25 network or any other X.25 network using
Telenet type operation.
Link Initiation
This bit is set on when attaChing to networks that
require link initiation to be done by the network only.
Advertisement
Table of Contents
