User manual

Wide Bank 28 DS3 - Release 2.4 July 2004 2-9
Product Description
Framing Modes

The Path Maintenance Data Link is a 28.2 Kbps terminal-to-terminal data link embedded in
the C-bits. See DS3 Path Maintenance Data Link on page 7-7.
 The ability to send a DS3 idle code to the network
 The DS3 idle code means that the DS3 is not carrying traffic
DS3 Multiframe Structure
The DS3 signal is partitioned into multiframes (M-frames) of 4760 bits each. The M-frames are
divided into seven M-subframes, each having 680 bits. Each M-subframe is further divided into
eight blocks of 85 bits, 84 of which are payload and one bit for frame overhead.
The structure of the DS3 multiframe is the same for both M23 and C-bit framing. As stated above,
the C-bits are used for different purposes.
Figure 2-2 shows how the frame is structured with the C-bits highlighted. Figures 2-5 through 2-8
provide details about the individual subframes.
Figure 2-2 Multiframe Structure
M Frame
= 4760 bits
X 84 F1 84 84 84 84 84 84 AIC FO Na FO FEA F1 S1 83
X 84 F1 84 84 84 84 84 84 C1 FO C1 FO C1 F1 S2 821
P 84 F1 84 84 84 84 84 84 CP FO CP FO CP F1 S3 812
M1 84 F1 84 84 84 84 84 84 C1 FO C1 FO C1 F1 S6 785
P 84 F1 84 84 84 84 84 84FO FO F1 3 S4 80
FEBE FEBE FEBE
MO 84 F1 84 84 84 84 84 84 DLt FO DLt FO DLt F1 4 S5 79
MO 84 F1 84 84 84 84 84 84 C1 FO C1 FO C1 F1 6 S7 77
M Subframe
= 680 bits
1
2
3
4
5
6
7