STANDARD PRODUCT
PM4328 TECT3
DATASHEET
PMC-2011596
ISSUE 1
HIGH DENSITY T1/E1 FRAMER
AND M13 MULTIPLEXER
information within the link rate octet in the V4 location is not used in synchronous
mode.
DS3 Tributary Mapping
Table 19 shows a DS3 tributary mapped within the first synchronous payload
envelope SPE1. The V5 indicator pulse identifies the V5 octet. The DS3 framing
format does not follow an 8KHz frame period so the floating DS3 multi-frame
located by the V5 indicator, shown in heavy border grey region in Table 19, will
jump around relative to the H1 frame on every pass. In fact the V5 indicator will
often be asserted twice per H1 frame, as is shown by the second V5 octet in
Table 19. The V5 indicator and payload signals indicate negative and positive
rate adjustments which are carried out by either putting a data byte in the H3
octet or leaving empty the octet after the H3 octet.
Table 19: DS3 Framing Format
SPE
COL #
DS3
1
DS3
2-56
DS3
57
DS3
58-84
DS3
Col 85
SBI COL#
1,4,7,10
ROW
13
16
SSS
184
SSS
268
1
2
3
4
5
6
7
Unused
Unused
Unused
H1
H2
H3
V5
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
DS3
Unused Linkrate
Unused Unused
Unused Unused
Unused Unused
8
9
Unused Unused
Unused Unused
DS3
DS3
DS3
DS3
V5
DS3
DS3
DS3
DS3
DS3
Because the DS3 tributary rate is less than the rate of the grey region, padding
octets are interleaved with the DS3 tributary to make up the difference in rate.
Interleaved with every DS3 multi-frame are 35 stuff octets, one of which is the
V5 octet. These 35 stuff octets are spread evenly across seven DS3 subframes.
Each DS3 subframe is eight blocks of 85 bits. The 85 bits making up a DS3
block are padded out to be 11 octets. Table 20 shows the DS3 block 11 octet
format where R indicates a stuff bit, F indicates a DS3 framing bit and I indicates
DS3 information bits. Table 21 shows the DS3 multi-frame format that is packed
into the grey region of Table 19. In this table V5 indicates the V5 octet which is
also a stuff octet, R indicates a stuff octet and B indicates the 11 octet DS3
block. Each row in Table 21 is a DS3 multi-frame. The DS3 multi-frame stuffing
format is identical for 5 multi-frames and then an extra stuff octet after the V5
octet is added every sixth frame.
PROPRIETARY AND CONFIDENTIAL
165
PMC [ PMC-SIERRA, INC ]
