Motorola T1/E1 - Manual (Page 22)

Canopy T1/E1 Multiplexer September 2004
T1/E1 Multiplexer FPGA Version 3.4
Page 22 of 73
Table 10: Frequency off-set by clock type
Clock
Type
Frequency Off-set
(accuracy over 24
hours)
Time to First
Frame Slip Application
Stratum 1
Clock 1 x10
-11
1 every 72 days Gateway Office
Stratum 2
Clock 1x10
-10
1 every 3.5 hours Toll Center
Stratum 3
Clock 3.7x10
-7
1 every 6 minutes
or
255 in 24 hours
Central Office
Stratum 4
Clock 3.2x10
-6
Up to 1 frame slip
every 4 seconds in
free-run Customer Premises Equipment
(PBX, Channel Banks, Routers)
The Canopy T1/E1 Multiplexer does not have an internal oscillator. Therefore, the unit
must be synchronized to a T1/E1 bit stream in order to accurately pass T1/E1 traffic. The
Canopy T1/E1 Multiplexer may be configured to synchronize to a near-end or far-end
Canopy T1/E1 Multiplexer.
Master and Secondary Clocks
The clock on each Canopy T1/E1 Multiplexer must be correctly configured to prevent
frame slips. Each of the four (4) T1/E1 ports may be configured as the Master clock
source or the Secondary clock source. Any port may be set to Master and any port may
be set to Secondary, however there may only be one (1) Master and one (1) Secondary
clock setting per unit.
Note: If neither the Master or Slave port is active, then the system will start at Port 1 and
search in logical order until it finds an active T1/E1 port, at which time it will assume this
to be the Master clock source.
Two scenarios are shown below, one scenario with Port 1 set to Master and Port 2 set to
Secondary. The second scenario shows Port 1 set to Secondary and Port 3 set to
Master.
Figure 7: Master and secondary clock settings (top view)
Issue 3