1 - PRELIMINARY INFORMATION
1-20
SRA 4 - 6/7/8/10/11/13 GHz (WB ODU) - UMN
911-381/02C0000 - Issue 3, July 2004
1.4.1.9
TU-3 Tributary unit
The composition of the TU-3 structure i shown in Fig. 1.9.
The transport capacity of structures which are part of TU-3 are:
–
container C-3:
C
C-3
=
8
x (
84 x 9
) x
8 x 10
3
= 48.384 Mbit/s
a
c
b
–
container VC-3:
C
VC-3
=
8
x (
9
+
84 x 9
) x
8 x 10
3
= 48.960 Mbit/s
a d
c
b
–
container TU-3:
C
TU-3
=
8
x (
3
+
6
+
85 x 9
) x
8 x 10
3
= 49.536 Mbit/s
a e
f
g
b
where:
a)
bit of which all bytes are composed
b)
STM-1 frame frequency
c)
byte composing C-3
d)
byte composing POH of VC-3
e)
byte for pointer allocation
f)
fixed stuffing byte
g)
byte composing VC-3.
Fig. 1.9
Composition of the structures C-3, VC-3 e TU-3
Fixed stuffing bytes
TU-3 PTR
3
6
1
85
0 1
596
595
H3
H2
H1
84
83
82
764
763
TU-3 PAYLOAD
VC3
9
1
84
H
O
P
C-3
