VBrick 9000 Series, Руководство по началу работы

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Streaming Video Basics
H.264 Encoding/Decoding Appliance Getting Started Guide 57
How Passthrough Works
VBrick appliances are able to receive data on a particular TCP/IP port and transparently
output that data to a serial port. Conversely, any data input to a serial port can be passed
through to other devices connected to that TCP/IP port. Devices include other VBricks or
special applications connected to the appropriate TCP/IP port. This feature is called "Serial
Port Passthrough." COM is assigned port 4439. A typical application is for two VBricks
connected to each other's TCP/IP port 4439. In this case, characters typed into a terminal
program attached to one VBrick's serial port appear on a terminal program attached to the
other VBrick's serial port. In this case, the TCP/IP network serves as an intermediary
between the serial ports of two VBrick appliances.
You must select configuration settings to enable Serial Port Passthrough. First it is necessary
to decide if the appliance will be designated as an
Initiator
or
Responder
of Passthrough
connections. If configured as an
Initiator
it will continuously attempt to setup a Passthrough
connection to other devices. When configured as a
Responder
it will accept up to 64
connections from
Initiator
appliances. It is possible to Disable Passthrough Mode, so that the
VBrick neither initiates nor responds to Passthrough requests. If a VBrick is set to be an
Initiator
, a
Destination
must be selected. The appliance will use the destination information
when trying to establish a connection. The destination can be configured as follows:
Since the medium used for setting up Passthrough connections is a generic TCP/IP port, any
IP device that is prepared to connect to a VBrick's port can be considered as a Passthrough
Initiator. The VBrick Responder appliance will not know the exact nature of the device at the
other end of the port. For example, a generic Telnet client configured to connect to a VBrick
on port 4439 will cause a VBrick
Responder
to start sending data from it's serial port, using
the connection it accepted from the Telnet client. If the appliance is configured as an
Initiator
and the
Responder
appliance has Passthrough disabled or is not on the network it will
continue to try to establish a connection.A VBrick appliance must be configured as a
Responder
to accept Passthrough connections initiated by other devices. In addition to the
Initiator versus Responder selection, the serial port operation settings must be entered to
establish a connection, baud rate, stop bits etc.
Dedicated Means that the initiator will attempt to make a Passthrough connection
to the configured Dedicated Destination and Port. The Dedicated
Destination can either be configured using IP Address or Host Name.
If set to Host Name, the Resolved Destination IP Address is derived
from the Host Name parameter. If set to IP Address, the Resolved
Destination IP Address is derived from the IP Address parameter.
Note Once a Passthrough connection is established between VBricks, the actual flow of data
is symmetric between the ends of the connection. That is, the behavior of the serial
ports with respect to typed characters will appear to be the same at both ends.