tmxf28155 ETC-unknow, tmxf28155 Datasheet - Page 403

• Manufacturer Part Number: tmxf28155
• Description: Tmxf28155 Super Mapper 155/51 Mbits/s Sonet/sdh X28/x21 Ds1/e1
• Manufacturer: ETC-unknow

Preliminary Data Sheet
TMXF28155/51 Super Mapper
May 2001
155/51 Mbits/s SONET/SDH x28/x21 DS1/E1
18 SPE Mapper Functional Description
(continued)
The TUG-3 has a structure of 9 rows by 86 columns: one column of null pointer indication (NPI) plus fixed stuffing
bytes, one column of fixed stuffing, and the other 84 columns are seven TUG-2s evenly distributed within the
TUG-3 payload.
18.6 DS3 to AU-3/STS-1 SPE Mapping (Used in Telcordia / ANSI Standards Based Systems)
DS3 is an asynchronous signal with a rate of 44.736 Mbits/s. This payload with other information bits (total
3.648 Mbits/s) is used to form the container C-3 (48.384 Mbits/s) which occupies 84 columns of an STS-1 frame.
One column of path overhead bytes is added to the C-3 container to make a VC-3. Finally, two columns of fixed
stuffing (column numbers 30 and 59) are added to VC-3 to form an STS-1 SPE (87 columns).
Stuffing (S bits) is used to rate adapt the DS3 payload to the SPE. Nine stuffing S bits are included in the C-3 con-
tainer. When no stuffing is used, the STS-1 SPE can accommodate a rate of 44.712 Mbits/s. When all nine stuffing
S bits are used, the STS-1 SPE can accommodate 44.784 Mbits/s. Since the DS3 coming from the M13 has a
nominal rate of 44.736 Mbits/s, stuffing is used for every third row of an STS-1 frame; or in other words, three S bits
per 125 µs are used for stuffing to achieve the DS3 rate.
18.7 DS3 to TUG-3 Mapping (Used in ITU/ETSI Standard Based Systems)
DS3 is an asynchronous signal with a rate of 44.736 Mbits/s. This payload with other information bits (total
3.648 Mbits/s) is used to form the container C-3 (48.384 Mbits/s) which occupies 84 columns of an STM-1 frame.
One column of path overhead bytes are added to the C-3 container to make a VC-3 (85 columns). Now a TUG-3
signal consists of 86 columns by 9 rows, therefore 3 bytes of TU-3 pointer (H1, H2, and H3 bytes) are placed on
rows 1 through 3 of the newly added column and fixed stuffing bits are placed on the remaining rows. Thus, a
TUG-3 frame of 9 rows by 86 columns is formed. Three TUG-3s are byte interleavingly multiplexed by the TMUX to
form an STM-1 signal.
Stuffing (S bits) is used to rate adapt the DS3 payload to the TUG-3. Nine stuffing Sbits are included in the C-3
container. When no stuffing is used, the TUG-3 payload can accommodate a rate of 44.712 Mbits/s. When all nine
stuffing S bits are used, the TUG-3 payload can accommodate 44.784 Mbits/s. Since the DS3 coming from the
M13 has a nominal rate of 44.736 Mbits/s, stuffing is used for every third row of a TUG-3 frame; or in other words,
three S bits per 125 µs are used for stuffing to achieve the DS3 rate.
18.8 SPE Mapper Basic Configuration
SPE mapper configuration programming is provided through registers SPE_MAP_CTL1—SPE_MAP_CTL3
(Table 153 on page
140).
When mapping to a STS-3/STM-1 rate, the SPE mapper requires configuration to select one of the three time slots
on the telecom bus that interfaces the TMUX. The register bits for selection are SPE_TSTS3TMSLOT[1:0] and
SPE_RSTS3TMSLOT[1:0]
(Table
153).
Selection of AU-3/STS-1 or TUG-3 mapping is provided through bits SPE_T_AU3_TUG3 and SPE_R_AU3_TUG3
(Table
153).
TUG-2 (virtual tributary) or DS3 data is selected with bits, SPE_T_AU3_TUG3 and SPE_R_AU3_TUG3.
18.9 DS3 Configuration
The SPE mapper is configured to select the source and destination of the DS3 signals. The configuration is deter-
mined with register bits, SPE_TDS3SRCTYP[1:0] and SPE_RDS3OUTTYP[1:0]
(Table
153). DS3 source/destina-
tion may be selected as loopback, external device pins, or M13.
Agere Systems Inc.
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