XRT75R12D_06 Datasheet, PDF (99/134 Pages) Exar Corporation – TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET

XRT75R12D
REV. 1.0.1 TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER
FIGURE 43. AN ILLUSTRATION OF TELCORDIA GR-253-CORE'S RECOMMENDATION ON HOW MAP DS3 DATA INTO
AN STS-1 SPE
• For DS3 Mapping, the STS-1 SPE has the following structure.
87 bytes
R R C1 25I
R R C1 25I
R R C1 25I
R R C1 25I
R R C1 25I
R R C1 25I
R R C1 25I
R R C1 25I
R R C1 25I
R C2 I 25I
R C2 I 25I
R C2 I 25I
R C2 I 25I
R C2 I 25I
R C2 I 25I
R C2 I 25I
R C2 I 25I
R C2 I 25I
R C3 I 25I
R C3 I 25I
R C3 I 25I
R C3 I 25I
R C3 I 25I
R C3 I 25I
R C3 I 25I
R C3 I 25I
R C3 I 25I
POH
I = [i, i, i, i, i, i, i, i]
R = [r, r, r, r, r, r, r, r]
C1 = [r, r, c, i, i, i, i, i]
C2 = [c, c, r, r, r, r, r, r]
C3 = [c, c, r, r, o, o, r, s]
Fixed
Stuff
i = DS3 data
r = fixed stuff bit
c = stuff control bit
s = stuff opportunity bit
o = overhead communications channel bit
Figure 43 was copied directly out of Telcordia GR-253-CORE. However, this figure can be simplified and
redrawn as depicted below in Figure 44.
FIGURE 44. A SIMPLIFIED "BIT-ORIENTED" VERSION OF TELCORDIA GR-253-CORE'S RECOMMENDATION ON HOW
TO MAP DS3 DATA INTO AN STS-1 SPE
POH
18r c 205i 16r 2c 6r 208i 16r 2c 2r 2o 1r s 208i
18r c 205i 16r 2c 6r 208i 16r 2c 2r 2o 1r s 208i
18r c 205i 16r 2c 6r 208i 16r 2c 2r 2o 1r s 208i
18r c 205i 16r 2c 6r 208i 16r 2c 2r 2o 1r s 208i
18r c 205i 16r 2c 6r 208i 16r 2c 2r 2o 1r s 208i
18r c 205i 16r 2c 6r 208i 16r 2c 2r 2o 1r s 208i
18r c 205i 16r 2c 6r 208i 16r 2c 2r 2o 1r s 208i
18r c 205i 16r 2c 6r 208i 16r 2c 2r 2o 1r s 208i
18r c 205i 16r 2c 6r 208i 16r 2c 2r 2o 1r s 208i
r - Fixed Stuff Bits
c ^{- Stuff Control/Indicator Bits}
o ^{- Overhead Communication Bits}
i ^{- DS3 Data Bits}
s ^{- Stuff Opportunity Bits}
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