ADTRAN 1200130L2 - Manual (Page 44)

3 0 FSU User Manual 61200.130L1-1
Chapter 4. Applications
Transparent Application
In cases when the user protocol is not supported by the FSU, the
transparent mode may be used. Transparent bit-oriented
protocol (BOP) or transparent asynchronous protocol may be
selected. This can be used for point-to-point connections only
because the FSU is transparent to the protocol address formats.
In the transparent BOP protocol, the FSU accepts an HDLC-like
protocol and encapsulates the information field of the HDLC
frames, transporting them across the frame relay network to the
specified virtual circuit and remote FSU port number. The
incoming frames must be spaced with at least one flag byte
(0x7E) and contain two bytes of CRC16 at the end of each frame.
Asynchronous protocols are supported by using the transparent
async mode. The FSU buffers async characters and encapsulates
the data portion of each character for transport across frame
relay using a programmable DLCI and remote FSU port number.
See Figure 4-5 and Table 4-D for an example of a transparent
BOP configuration. See Figure 4-6 and Table 4-E for an example
of a transparent asynchronous application.
Router Router
HDLC HDLC
DTE1 DTE1
FSU FSU
UNI
N
UNI
FRAME RELAY
REMOTE LOCAL
Figure 4-5
Transparent BOP Application