Title: Clocks for the Synchronized Network: Common Generic Criteria
Issue Number: 04
Issue Date: 2009/10/06
Replaces: GR-1244-CORE Issue 03
Addendum: n/a, Bulletin: n/a, Revision: n/a, Supplement: n/a, Volume: n/a
Abstract: Issue 4 of GR-1244, Clocks for the Synchronized Network:
Common Generic Criteria, replaces Issue 3, and is a component of
FR-SONET-01, and FR-TRANSPORT-SYSTEMS-01.
The digital synchronization network consists of clocks connected by
digital facilities. This document provides criteria that apply to these
various clocks deployed in telecommunications equipment such as
transport Network Elements (NEs), Digital Switches, and Timing Signal
Generators (TSGs). Since these clocks can have a critical impact on
network performance, GR-1244 may be of significant value to
telecommunications equipment manufacturers (including both
synchronization-related component and system manufacturers) and
telecommunications service providers.
The updates in Issue 4 should significantly assist the reader's
understanding of the criteria (and expected clock performance
characteristics) in areas such as holdover stability, wander generation,
and phase build-out. Specific updates include:
The equations for calculating fractional frequency offset and drift were
corrected, and additional information on the use of those equations was
The temperature component of the holdover frequency stability
requirement for stratum 3 clocks was changed to align with the
corresponding specification in ATIS-0900101
Significant explanatory test was added regarding the holdover stability
curves provided in Section 5
Additional explanatory text was provided regarding the conditions under
which the wander generation requirements apply
The proposed value of one of the parameters used in defining test cases
for testing a clock's phase build-out performance was changed to reflect
the long time constants of the filters used in stratum 2 and 3E clocks
Additional information was provided regarding the applicability of
various criteria to NEs/clocks used in SONET or 'synchronous Ethernet'
In addition, minor corrections or clarifications were made in the text
in various sections of the document, references to ANSI T1 standards
were changed to reflect their reclassification as ATIS standards, and
references to the ITU-T documents related to synchronous Ethernet were
added to a number of sections.
GR-1244 replaced TR-NWT-001244.
When using GR-1244, you may want to refer to GR-57, GR-63, GR-82,
GR-253, GR-378, GR-436, GR-454, GR-474, GR-487, GR-496, GR-499, GR-820,
GR-839, GR-1089, GR-2830, TR-NWT-000170, and various standards documents.