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XRT79L71
PRELIMINARY
425
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
bytes will contain a "0" within their MSB. These remaining 15 bytes will transport 15 ASCII characters as is
required by the E.164 Terminal Numbering format.
The XRT79L71 will support the transmission and reception of this Trail-Access Point Identifier Message, via
the E3, ITU-T G.832 data-stream.
For more details on how the Transmit DS3/E3 Framer block and the
Receive DS3/E3 Framer block within the XRT79L71 handle these messages, please see SEE”TRANSMIT The Maintenance and Adaptation Byte (MA)
The exact role of the MA byte has been changed per the October 1998 Revision of the ITU-T G.832
specification document. However, the XRT79L71 supports both the Pre-October 1998 version of the MA byte
and the Post-October 1998 version of the MA byte. Each of these versions of the MA byte is briefly described
below.
The Post-October 1998 Version of the MA Byte
The Post-October 1998 Version of the MA byte contains the following bit-format.
Bit 1 - FERF/RDI (Far-End Receive Failure/Remote Defect Indicator)
Bit 1 within the MA byte carries the FERF (Far-End Receive Failure)/RDI (Remote Defect Indicator) bit within
the E3, ITU-T G.832 frame. The purpose of the FERF/RDI bit-field within the MA byte is to permit a given E3
Terminal Equipment to transmit a FERF/RDI indicator to the remote terminal equipment. Whenever a Near-
End E3 Terminal declares a service-affecting defect condition (e.g., the LOS, LOF or the AIS defect condition)
within its incoming E3 data-stream, then it will inform the remote terminal equipment (e.g., the source of this
defective E3 signal) of this fact by transmitting the FERF/RDI indicator back out to the Remote Terminal
Equipment via the outbound (returning) E3 signal. This Near-End E3 Terminal will indicate the FERF/RDI
condition by setting the FERF/RDI bit-field, within each outbound E3 frame to "1" for the duration that the
Receive-related defect condition exists. Conversely, this Near-End E3 Terminal will indicate that it is NOT
transmitting the FERF/RDI indicator by setting the FERF/RDI bit-field to "0" for the duration that no Receive-
related/Service-affecting defect conditions exists.
This concept of transmitting the FERF/RDI indicator in
response to certain defect conditions is reinforced in Figures 196 through 199, below.
Figure 196 presents an illustration of a given Near-End Terminal that is exchanging E3 data with a remote
terminal, in an un-erred manner.
FIGURE 195. THE BIT FORMAT OF THE POST OCTOBER 1988 VERSION OF THE MA BYTE
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Bit 8
FERF/RDI
FEBE/REI
Payload_Type[2:0]
SSM Multi-Frame Indica-
tor[1:0]
SSM Bit