Page 80 - Optical Switching And Networking Handbook
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04_200023_CH03/Batesx 1/17/01 9:42 AM Page 65
SONET 65
columns and all nine rows. This creates 27 bytes of transport over-
head. As shown in Figure 3-8, the transport overhead is divided into
two pieces. The first three columns and the first three rows (9 bytes)
are used for section overhead. The remaining six rows in the first
three columns (18 bytes) are used for line overhead.
Figure 3-7 90 Columns
The SONET frame
9
R
o
w
s
Figure 3-8
The transport Section
=3X3
overhead is divided
into section and
line overhead.
Line
3X6=18
Transport SONET OC-1 Frame
O/H= 3X9= 27
