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Stratum levels
Table 62
Node categories and stratum levels
Accuracy
Holdover
Hardware
Duplication
MTIE During
Rearrangement
Pull-in Range
Dedicated Timing
Required
Frame slip
553-3001-201
Standard 1.00
Clock Controller description and installation
In a digital network, nodes are synchronized using a priority master/slave
method. Digital nodes are ranked in Stratum levels 1 to 5. Each node is
synchronized to the highest ranking node in its neighborhood with which it
has a direct link. Refer to Table 62.
Stratum 2
-8
+/- 1.6 * 10
Hz
-10
1 * 10
per day
Required
MTIE <= 1 usec Phase
Change Slope: <= 81
ns in any 1.326 msec
-8
3.2 * 10
Hz
Required
Note 1: Non-duplicated clock hardware that meets all other stratum 3
requirements is referred to as stratum 3ND.
Note 2: Stratum 4 clock hardware that meets MTIE requirements during
rearrangements is referred to as 4E.
Digital signals must have accurate clock synchronization for data to be
interleaved into or extracted from the appropriate timeslot during
multiplexing and demultiplexing operations. A Frame Slip is defined (for 2
Mbyte links) as the repetition of, or deletion of the 256 data bits of a CEPT
frame due to a sufficiently large discrepancy in the read and write rates at the
buffer (clocks are not operating at exactly the same speed).
October 2003
Stratum 3
-6
+/- 4.6 * 10
Hz
<= 255 frame slips in
1st 24 hours
Required (Note 1)
MTIE <= 1 usec Phase
Change Slope: <= 81
ns in any 1.326 msec
-6
9.2 * 10
Hz
Required
Stratum 4
-5
+/- 3.2 * 10
Hz
Not Required
Not Required
No Requirement
(Note 2)
-5
6.4 * 10
Hz
Not required
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