XRT86L30
REV. 1.0.1
SINGLE T1/E1/J1 FRAMER/LIU COMBO
14.5
T1 Extended Superframe Format (ESF)
In Extended Superframe Format (ESF), as shown in Figure 112 and Table 179, the multiframe structure is
extended to 24 frames. The timeslot structure is identical to D4 (SF) format. Robbed-bit signaling is
accommodated in frame 6 (A-bit), frame 12 (B-bit), frame 18 (C-bit) and frame 24 (D-bit).
The F-bit pattern of ESF contains three functions:
1. Framing Pattern Sequence (FPS), which defines the frame and multiframe boundaries.
2. Facility Data Link (FDL), which allows data such as error-performance to be passed within the T1 link.
3. Cyclic Redundancy Check (CRC), which allows error performance to be monitored and enhances the reli-
ability of the receiver’s framing algorithm.
FIGURE 112. T1 EXTENDED SUPERFRAME FORMAT
Signalling
Information
Bit 7
During:
Frame 24
D
C
B
Frame 18
Frame 12
Frame 6
8 Bits per
Timeslot
A
Bit
0
Bit
1
Bit
Bit
3
Bit
4
Bit
5
Bit
6
Bit
7
2
CRC
CRC
FD
FD
L
FPS
or
Fs
L
24 Timeslots per Frame
Frame = 193 Bits
FP
TS
1
TS
2
-----------------
TS
13
13
------------------
TS
TS
1
TS
2
-----------------
-
TS
------------------
-
TS
24
So
Fr
s
-
-
24
Multiframe
FR
1
FR
2
-----------------
FR
13
13
------------------
FR
23
23
FR
24
24
ESF = 24
Frames
FR
1
FR
2
-----------------
-
FR
------------------
-
FR
FR
-
-
258
EXAR [ EXAR CORPORATION ]
