TMXF28155 Supermapper
155/51 Mbits/s SONET/SDH x28/x21 DS1/E1
Data Sheet
June 2002
376
Agere Systems Inc.
17 TMUX Functional Description
(continued)
In case of overflow, depending on the value programmed in the microprocessor interface register bit
SMPR_SAT_ROLLOVER (
Table 77 on page 70
), the B1 error counter will either roll over or saturate at the maxi-
mum value until cleared.
17.5.5 J0 Monitor
J0 (section trace overhead) monitoring is done via register bits TMUX_J0MONMODE[2:0]; see
Table 105 on
page 97
. This J0 monitoring has six different monitoring modes, as follows:
I
TMUX_J0MONMODE[2:0] = 000: the TMUX latches the value of the J0 byte every frame for a total of
16 bytes into registers TMUX_J0DMON[16—1][7:0]; see
Table 142 on page 123
. The TMUX compares the
incoming J0 byte with the next expected value (the expected value is obtained by cycling through the previously
stored 16 received bytes in round-robin fashion). The TMUX will perform a byte-by-byte comparison and, if differ-
ent, set the section trace identifier mismatch state register bit, TMUX_RTIMS; see
Table 101 on page 94
. Any
change to TMUX_RTIMS will be reported via delta and interrupt register bits TMUX_RTIMSD; see
Table 92,
starting on page 81
and TMUX_RTIMSM; see
Table 96 on page 90
.
I
TMUX_J0MONMODE[2:0] = 001: this is the SONET framing mode. The hardware looks for a 0x0A character to
indicate that the next byte is the first byte of the path trace message. The J0 byte message is continuously writ-
ten into TMUX_J0DMON[1—16][7:0] registers with the first byte residing at the first address. If any received byte
does not match the previously received byte for its location, then the state register bit, TMUX_RTIMS, is set. Any
change to RTIMS will be reported via delta and interrupt mask register bits TMUX_RTIMSD and
TMUX_RTIMSM.
I
TMUX_J0MONMODE[2:0] = 010: this is the SDH framing mode. The hardware looks for the byte with the most
significant bit (MSB) set to one, which indicates that the next byte is the second byte of the message. The rest of
operation is the same as in SONET framing mode.
I
TMUX_J0MONMODE[2:0] = 011: a new J0 byte (TMUX_J0DMON[1][7:0]) will be detected after the number of
consecutive consistent occurrences of a new pattern in the J0 overhead byte as determined by the values in reg-
isters TMUX_CNTDJ0[3:0]; see
Table 108 on page 100
. Any changes to this byte are reported via delta and
interrupt mask registers TMUX_RTIMSD and TMUX_RTIMSM. The TMUX_RTIMSD delta bit in this mode indi-
cates a change in state for the TMUX_J0DMON[1][7:0] byte and the state register bit, TMUX_RTIMS, is not
used.
I
TMUX_J0MONMODE[2:0] = 100: the user will program the 16 expected values of J0 in the SONET frame into
registers TMUX_EXPJ0DMON[1—16][7:0]; see
Table 141 on page 123
. The first expected byte (the byte follow-
ing the 0x0A character) is written into the first location, TMUX_J0DMON[1][7:0]. The TMUX performs a byte-by-
byte comparison of the incoming J0 sequence with the stored expected value. If different, the TMUX will set the
section trace identifier mismatch state register bit, TMUX_RTIMS (
Table 101 on page 94
). Any change to
TMUX_RTIMS is reported via register bits TMUX_RTIMSD (delta state) and TMUX_RTIMSM (interrupt mask).
I
TMUX_J0MONMODE[1:0] = 101: the user will program the 16 expected values of J0 in the SDH frame in regis-
ters TMUX_EXPJ0DMON[1—16][7:0]. The first byte of the message has the MSB set to 1. The TMUX performs
a byte-by-byte comparison of the incoming J0 sequence with the stored expected value. If different, the TMUX
will set the section trace identifier mismatch state register bit, TMUX_RTIMS (
Table 101 on page 94
). Any
change to TMUX_RTIMS will be reported via register bits TMUX_RTIMSD (delta state) and TMUX_RTIMSM
(interrupt mask).
I
TMUX_J0MONMODE[1:0] = 110 and 111 are currently undefined.
17.5.6 Descrambler
A frame synchronous descrambler of length 127 and generating polynomial x
7
+ x
6
+ 1 will descramble the entire
STS-3/STM-1 (or STS-1) signal except for the first row of overhead. The scrambler will be set to 1111111 on the
first byte following the last section overhead byte in the first row (i.e., after byte J0 for STS-1). The descrambler
operates in a byte-wide mode.
The frame descrambler can be enabled or disabled using register bit TMUX_RHSDSCR (
Table 103 on page 96
).