
XRT86SH221
PRELIMINARY
65
SDH-TO-PDH FRAMER/MAPPER WITH INTEGRATED 21-CHANNEL E1 SH LIU
REV. P1.0.5
I
If bits 6 through 8 of the K2 byte are not used for other purposes (e.g., the linear APS mode indication),
the LTE shall deactivate RDI-L by inserting the code '000' in bits 6, 7, and 8 of the K2 byte within 125
μ
s
of terminating the defect that caused it.
I
If bits 6 through 8 of the K2 byte are used for other purposes, the LTE shall deactivate RDI-L by inserting
an appropriate code in bits 6, 7, and 8 of the K2 byte within 125
μ
s of terminating the defect that caused
it to be sent (assuming it has been sent for any minimum RDI-L assertion time supported by the NE).
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When LTE generates RDI-L, it should generate it for at least 20 frames.
SECTION TRACE GENERATION (J0/Z0)
The txstoh_cont block allows three methods in the transmission of the J0/Z0 bytes:
Method 1:
The J0 byte is set to all 1 in accordance with the SDH standard rule.
Unless it is being used for a defined purpose (e.g., to carry a section trace message once the details of that
feature are defined) each J0 and Z0 byte shall be set to a binary number corresponding to its order of
appearance in the STM-N frame (i.e., the J0 byte shall be set to 00000001, the first Z0 byte shall be set to
00000010, etc.).
Method 2:
The J1 byte is obtained from the hardware input
Method 3:
The J1 byte is obtained from the message written by software into the J1 message buffer
Method 1 is the default unless the software control specifies otherwise. The Z0 bytes are always generated
according to the above rules.
The section trace (J0) transmit buffers use a 64x8 single port ram as in the case of the path trace transmit
buffers. The memory segments contain the J0 section trace buffers and operate in the same way as the J1
transmit path trace buffers.
REI-L GENERATION (M0/M1)
The txstoh_cont block allows three methods in the transmission of the M0/M1 bytes:
Method 1 :
The REI-L signal is set according to the B2 error count by the receiver blocks from the most
recently received frame
Method 2 :
The REI-L signal is obtained from the hardware input
Method 3 :
The REI-L signal is obtained from software
Method 1 is the default unless software chooses to enable either method 2 or 3.
S1/F1/E1/E2 SELECTION
The txstoh_cont block allows either hardware or software insertion of the S1, F1, E1, and E2 bytes. The default
generation method for the S1 byte is reading from the software registers. The default generation method for
the E1, F1, and E2 bytes is hardware insertion. The registers contain all zeros upon reset.
DATACOM (D1-D12) SELECTION
The data communication bytes are inserted via hardware only.
UNDEFINED SDH OH BYTES
The remaining bytes of the STM-N transport overhead are all currently undefined. The txstoh_cont block
inserts all zeros in those bytes in accordance with the SDH standard.
I
An SDH NE shall have the capability to ignore the values contained in all undefined and unused bits and
bytes [except for BIP-8 calculations] to prevent misinterpretation of the received patterns.
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An SDH NE should send an all-zeros pattern (before scrambling) in undefined bits and bytes. All-zero
patterns should also be sent in defined bits and bytes if the NE does not support the defined function or
if the function has been disabled by the user.