Agilent Technologies HDMP-3001 manual Pattern Acceptance and Com

Table 13. Pointer Processing

Norm_point: Normal NDF AND match of ss bits AND offset value in range.

NDF_enable: NDF enabled AND match of ss bits AND offset value in range.

AIS_ind: 11111111 11111111.

Incr_ind:Normal NDF AND match of ss bits AND majority of I bits inverted AND no majority of

D bits inverted AND previous NDF_enable, incr_ind or decr_ind more than three frames ago.

Decr_ind: Normal NDF AND match of ss bits AND majority of D bits inverted AND no majority

of I bits inverted AND previous NDF_enable, incr_ind or decr_ind more than three frames ago.

Inv_point: Any other state OR norm_point with offset value not equal to active offset.

Table 14. Pointer Tracking

Norm_point: Normal NDF AND match of ss bits AND offset value in range.

Conc_ind: NDF enabled and pointer value = 1111111111

AIS_ind: 11111111 11111111

Inv_point: Any other state

pattern is found, the framer goes into frame, J1_OOF = 0. Once the J1 monitor framer is in frame, it remains in frame until three con- secutive path trace frames are received with at least one MSB bit error. (In SONET mode, the J1 frame indication is always held in the in frame state, J1_OOF = 0.) The J1_OOF_D delta bit is set

3.9.4.9.2SONET J1 Capture

When in SONET mode, the HDMP-3001 can be provisioned to capture a sample of the path trace message. When J1_READ transi- tions from 0 to 1, the HDMP-3001 captures 64 consecutive J1 bytes from the specified tributary and writes them to RX_J1[63:0]_[7:0].

No path trace frame structure is defined for SONET, but GR-253 does recommend that the 64-byte sequence consist of a string of ASCII characters padded out to 62 bytes with NULL characters (00) and terminated with <CR> (0D) and <LF> (0A) bytes. If the

J1_MODE bit is set, the HDMP-

3001 captures the first 64 byte string it receives in the J1 byte position that ends with {0D, 0A}. If the J1_MODE bit is zero, the HDMP-3001 captures the next 64 J1 bytes without regard to their content. On completion of the capture, the HDMP-3001 sets the J1_AVL event bit.

3.9.4.9.3 16-Byte J1 Monitoring

In SDH mode, the J1 bytes are ex- pected to contain a repeating

16-byte path trace frame that in- cludes the PAPI. In this mode, the J1_READ, J1_MODE, and J1_AVL bits are not used. J1 monitoring consists of locking on to the start of the 16-byte path trace frame and examining the received path trace frames for values that match consistently for three consecutive path trace frames. When a consis- tent frame value is received, it is written to RX_J1[15:0]_[7:0]. The first byte of the path trace frame (which contains the frame start marker) is written to RX_J1[15]_[7:0].

Framing. The MSBs of all path trace frame bytes are zero, except for the MSB of the frame start marker byte. The J1 monitor framer searches for 15 consecu- tive J1 bytes that have a zero in their MSB, followed by a J1 byte with a one in its MSB. When this

when J1_OOF changes state.

Pattern Acceptance and Com-

parison. Once in frame, the J1 monitor block looks for three con- secutive 16-byte path trace frames. When three consecutive identical frames are received, the accepted frame is stored in RX_J1[15:0]_[7:0].

Accepted frames are compared to the previous contents of these registers. When a new value is stored, the RX_J1_D delta bit is set.

3.9.4.9.4BIP-8 (B3) Checking

The HDMP-3001 checks the re- ceived B3 bytes for correct BIP-8 values. Even parity BIP-8 is calcu- lated over all bits in the SPE/VC (including the POH) each frame. These values are then compared to the B3 values received in the following frame. The comparison

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