DS-1 configuration 2-5
Digital Switching Systems DMS-250 ISDN Reference Manual MWC14 (CSP14)
•
The extended superframe format consists of 24 frames and is supported
only on DS-1 card 6X50AB.
The 8-kbit/s F-bit channel is divided into three separate channels:
• Framing pattern sequence (FPS)—a 2-kbit/s channel. Beginning with
frame four (extended superframe format bit 579), the framing bit of
every fourth frame forms the following:
— FPS 001011 (determines the mainframe)
— superframe format
— robbed bit signaling synchronization
The superframe format and extended superframe format are datafilled
under the frame format field in table CARRMTC.
• facility data link—a 4-kbit/s channel. The 6X50AB uses FDL to convey
remote alarm information or to transmit all ones, as selected in service
change.
• cyclic redundancy check—a 2-kbit/s channel. CRC carries the CRC-6
code. CRC indicates one or more bit errors in a block, or bits from the
received bit stream. CRC is used as an end-to-end bit error rate indicator.
Channel ordering sequence
The channel ordering sequence is shown in Table 2-3.
Table 2-3
Channel ordering sequence
Time slot D3/D4/ESF D2
1 112
2213
331
4417
555
6621
779
8815
993
—continued—
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