How does ONT generate the OOFOTL alarm insertion for OTL3 and OTL4?
Response
ONT generates the OOFOTL alarm by manipulating the FAS bytes at the transition between the OA1 and OA2 bytes (i.e. bytes 3 and 4), and in a bursty fashion as follows.
OA1 = not (0xF6) = 0x09 OA2 = not (0x28) = 0xD7 OTL3: 5 frames with errored FAS followed by 512 frames with error free FAS OTL4: 5 frames with errored FAS followed by 256 frames with error free FAS
OA1 = not (0xF6) = 0x09
OA2 = not (0x28) = 0xD7
OTL3: 5 frames with errored FAS followed by 512 frames with error free FAS
OTL4: 5 frames with errored FAS followed by 256 frames with error free FAS