Configuring PAD/ATPAD Ports 23
PAD Port Configuration
PAD XON/OFF Support Using X.25 Interrupt Packets
What is It?
There is a Customer Software Key (CSK) that enables the transmission of XON/
XOFF asynchronous data characters across a Public Data Network (PDN) using
X.25 Interrupt packets.
This improves the transmission of flow control information between local and
remote PAD ports on PathBuilder S200 series switches. Since X.25 Interrupt packets
travel at a higher priority through the PDN, flow control information between PAD
ports is communicated more thoroughly by letting you control the starting and
stopping of the asynchronous data characters stream.
How It Works
By enabling the CSK for this feature whenever a PathBuilder S200 series switch
PAD port receives an XON or XOFF flow control character from a user terminal or
networking device, the XON/OFF enhancement sends the flow control characters
across the PDN as X.25 Interrupt packets for faster transmission to the remote PAD
port.
For example, as shown in Figure 5, when User 1 wants to stop User 2 from sending
information, User 1 sends an XOFF character to the PAD port on the local
PathBuilder S200 series switch. Then the local PathBuilder S200 series switch sends
an X.25 Interrupt Packet to the remote node on the other side of the network, where
the XOFF character is passed on to User 2. This stops User 2 from sending anymore
data.
To let User 2 send information again, User 1 sends an XON character into the PAD
port on the local PathBuilder S200 series switch, which sends an X.25 Interrupt
Packet to the other node, and the XON character is passed on to User 2. This allows
User 2 to begin sending data again.
Figure 5. Example of Transmitting XON/OFF Frames Across PDN with
X.25 Interrupt Packets
Note
The user devices shown in Figure 5 can be networking devices or asynchronous
user terminals. Remember that the CSK for this feature must be enabled in order
to transmit flow control characters as X.25 Interrupt packets. If the CSK is not
enabled, the feature is not supported.
Also, for this feature to work, user devices at both ends of the network must be
connected to PathBuilder S200 series switches.
Set the PAD Profile record parameters Device Flow Control and PAD Data
Restraint to 1 for both PAD ports. Enabling the PAD Enhancement CSK.
PDN
PB S200
User 1
User 2
PAD Port
PAD Port
X.25 ports
X.25 VC
PB S200
