T-8110L AGERE [Agere Systems], T-8110L Datasheet - Page 118

• Manufacturer Part Number: T-8110L
• Manufacturer: AGERE [Agere Systems]

Ambassador T8110L H.100/H.110 Switch
12 Connection Control
12.2 Switching Operation
12.2.2 Standard Switching (continued)
12.2.2.1 Subrate (continued)
Subrate Switching Overview
Traditional byte-oriented TDM data switching provides 8 bits of data per time slot, or channel, regardless of the
TDM stream bit rate. A particular channel occurs once every 8 kHz frame, and there are 8K frames per second.
This allows for a channel data propagation rate of (8 bits/frame * 8K frames/s = 64 kbits/s).
Refer to Figure 24 and Table 97.
Subrate refers to switching fractional portions of the byte-oriented TDM data streams. The T8110L allows the 8 bits
of a byte-oriented channel to be broken into multiple channels of fewer bits, either two 4-bit channels, four 2-bit
channels, or eight 1-bit channels. This lowers the data propagation rate per channel, but increases the overall
channel capacity for a given time slot. Refer to Table 96 and Table 97.
Table 96. TDM Data Stream
Notes:
Bit subrate = 8 channels per time slot, 1 bit per channel.
Di-bit = 4 channels per time slot, 2 bits per channel.
Nibble subrate = 2 channels per time slot, 4 bits per channel.
Byte (no subrate) = 1 channel per time slot, 8 bits per channel.
118
Nibble
Di-Bit
Byte
Bit
8 Mbits/s
4 Mbits/s
2 Mbits/s
EACH CHANNEL CONTAINS ONE 8-BIT
BYTE, REGARDLESS OF THE TDM
DATA STREAM BIT RATE
7
7:6
0
0
1
6
(continued)
(continued)
0
2
7:4
Figure 24. TDM Data Stream Bit Rates
1
3
5
4
2
One Time slot (or Channel)
5:4
5
TDM STREAM BIT RATE = 2 Mbits/s: EACH STREAM HAS
32 TIME SLOTS (CHANNELS) PER FRAME
TDM STREAM BIT RATE = 8 Mbits/s: EACH STREAM HAS
128 TIME SLOTS (CHANNELS) PER FRAME
TDM STREAM BIT RATE = 4 Mbits/s: EACH STREAM HAS
64 TIME SLOTS (CHANNELS) PER FRAME
1
ONE FRAME (8 kHz)
6
4
TDM Stream Bit rate = 8MB/s: each stream has
3
128 timeslots (channels) per frame
7
7:0
3
3:2
124
2
62
125
3:0
31
126
Agere Systems Inc.
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127
1:0
0