Verilink 9000 Series (34-00271) Product Manual - Manual (Page 198)

176 C HAPTER 10: L EGACY O PTIONS
When this option is set for a printer, it helps prevent the print and pause condition
prevalent with remote print devices. This option can only be turned on for one
device per port.
M - Flush Input For
Unknown Address
As shown in Figure 10-20, when using group polling, the downstream device can
send in a message for any device it has defined. It is possible, through
misconfiguration, that the upstream device (the MultiPro platform) does not have
all of the devices defined that the downstream device does. In this case, it is
possible for the downstream device to send a message to the MultiPro unit for an
address that the MultiPro platform knows nothing about. In a normal situation, the
MultiPro unit simply does not respond to the message and resumes group polling.
Depending on the sophistication of the downstream unit, this may create a
deadlock situation and prevent other traffic from flowing.
The purpose of this option is to prevent a deadlock situation from occurring. This
option is set on for the group address only and instructs the MultiPro unit to ACK
any message it receives for an unknown address and then throw it away.
Figure 10-19 The Normal Sequence when Messages Are Spooled
DOWNLOAD CONFIG
MODE BACKUP NET ALARM POWER
PRISM 9111 T R A N S P O R T
®
Delivery Confirmation
Message Queued
Laser printer
Sequence When Using Spooling
The host port accepts a message for a device.
The host port stops accepting messages for the device.
The message travels through the network to queue up at the terminal port.
The terminal port delivers the message to the device.
A confirmation of delivery is sent to the host port.
The terminal port begins delivering the message to the device /
The host port begins accepting the second message.
DOWNLOAD CONFIG
MODE BACKUP NET ALARM POWER
PRISM 9111 T R A N S P O R T
®
DOWNLOAD CONFIG
MODE BACKUP NET ALARM POWER
PRISM 9111 T R A N S P O R T
®
Terminal 01 Terminal 02 Terminal 03
Group Poll
Message from terminal 03
ACK
Figure 10-20 Typical Application for the Flush Input for Unknown Address Option