User guide

August 2001 95
Understanding E1 Trunks
The transmitting end formats the E1 data into frames so the
receiving end can interpret the data. One frame consists of
32 8-bit timeslots. Timeslots 0 and 16 are reserved for framing
and signaling information. The remaining 30 timeslots each
carry 8 bits of information for a single E1 channel. Timeslots
1RDG_15 carry data for channels 0-14, and timeslots 17-31
carry data for channels 15-29, as shown in Figure 19.
Figure 19. An E1 Frame Carrying 32 8-bit Timeslots
Each frame has a period of 125 µs, or 8000 frames per second.
This means that each channel receives 8000 8-bit timeslots per
second and operates at 64 Kb/s,
8000 timeslots/second x 8 bits/timeslot = 64 Kb/s
01
2
34
3130
1
0
292827
3130
26
25
01100111
8-bit timeslot
DS1 125 S