ADC HIGAIN HDSL2 Manual page 31

152-231-116-01, Revision 01
first bit is numbered bit 0, bits 3088, 3474, and 5790 are logical zeroes and all other bits in the pattern are logical
ones.
An alternative interpretation of the AIS-CI signature is that the AIS signal modified by the AIS-CI signature is
equivalent to an ESF signal in which the FPS bits, the CRC-6 bits, and the payload are set to all ones and the DL
is overwritten by the pattern 01111100 11111111.
The NAIS option controls the AIS-CI feature. When NAIS is set to CI, the AIS to AIS-CI conversion
is enabled. When NAIS is set to AIS, the conversion is inhibited.
RAI to RAI-CI toward NET (RACI). The H2TU-C-231 List 1F in conjunction with the H2TU-R-402 List 4
supports the RAI-CI function.
The RAI-CI signal is a RAI signal which contains a signature indicating that an LOF or AIS failure has occurred
in the customer installation (CI) at the H2TU-R unit and that the defect or failure which caused the origination of
that RAI is not found in the signal from the network. Therefore, RAI-CI is transmitted toward the network when
the following two conditions are simultaneously true at the point from which RAI-CI originated (at the H2TU-R,
towards the network):
• RAI is received from the CI.
• No LOF, LOS, or AIS failure is detected in the signal received from the network.
Sending RAI-CI terminates within 500 µ s when either of the following occurs:
•
Cessation of RAI from the CI.
•
Declaration of LOF, LOS, or AIS in the signal from the network.
To prevent the transmission of RAI-CI during the failure-clearing interval of a network failure, the transition from
RAI to RAI-CI is delayed for 20 seconds following the detection of conditions 1 and 2 above. Since RAI-CI meets
the definition of RAI, it may be detected and used exactly as RAI is used. The longer period of time required for
detection of RAI-CI does not affect its use for functions which require RAI.
The RAI-CI pattern is a function of the payload frame format as follows:
•
ESF — The RAI-CI signal is a repetitive pattern in the FDL with a period of 1.08 seconds. RAI-CI is formed
by sequentially interleaving 0.99 (+/- 2 ms) seconds of the normal message 00000000 11111111
(right-to-left) with 90 milliseconds (+/- 2 ms) of the message 00111110 11111111 (right-to-left) to flag the
signal as RAI-CI.
•
SF — The SF RAI-CI signal is transmitted inband by setting each of the 24 channel time slots to 1000 1011
(left-to-right). In addition to the criteria specified above, the generation of SF RAI-CI has to be held off for
1 second to examine the DS0s for a framed, all-zeros pattern. If present, the generation of SF RAI-CI is
suspended for the duration of the all-zeros pattern.
Since the RAI to RAI-CI conversion modifies the payload, a RACI option is available to inhibit
the RAI to RAI-CI conversion for those applications that cannot tolerate payload modifications.
H2TU-C-231 List 1F October 2, 2000
Provisioning
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