Users Guide

Table 37. Supported standards
Supported standards Description
G.8261 Timing and synchronization aspects in packet networks.
NOTE: For G.8261, test cases 12-17 defined in Appendix VI of G.8261 standard can be
performed only in a future OS10 release with ITU.G.8275.2 profile support.
G.8262 Timing characteristics of the Synchronous Ethernet Equipment Clock (EEC).
G.8262.1 Timing characteristics of the enhanced Synchronous Ethernet Equipment Clock (eEEC).
G.8264 Distribution of timing information through packet networks.
Clock source selection
The clock selection algorithm selects the best available synchronization source from the Candidate sources. OS10 supports the
following clock selection modes:
● QL-enabled
● QL-disabled
Each mode uses different criteria to select the best available clock source. Use the sync-e mode command to configure the
QL mode to select the clock source for synchronization.
Use the sync-e esmc command to enable ESMC capability in the QL-enabled mode.
QL-enabled mode
In the QL-enabled mode, the switch considers the following factors when selecting a clock source on the SyncE-enabled
interfaces:
● Clock quality level (QL)
● Clock availability or signal fail through QL-FAILED
● Priority
● External commands (SyncE force switch or manual switch)
In this mode, the switch always selects the clock source with the best QL value. SSM codes indicate the QL values, which are
defined for the different regions such as Europe and America (see sync-e ssm-network-option). When multiple clock
sources are available on the network, a clock source is selected according to the following rules:
● If no external switch commands are active, the switch selects the clock source with the highest QL that does not experience
a signal fail condition.
● If multiple clock sources have the same highest QL, the clock source with the highest priority is selected.
● If multiple clock sources have the same highest priority and QL, the switch remains synchronized to the current clock source
or an arbitrary clock source from the group is selected.
QL-disabled mode
In the QL-disabled mode, the switch considers the following factors when selecting a clock source on the SyncE-enabled
interfaces:
● Clock availability or signal fail through QL-FAILED
● Priority
● External commands (SyncE force switch or manual switch)
When multiple clock sources are available on the network, a clock source is selected according to the following rules:
● If no external switch commands are active, the switch selects the clock source with the highest priority that does not
experience a signal fail condition.
● If multiple clock sources have the same highest priority, the switch remains synchronized to the current clock source or an
arbitrary clock source from the group is selected.
System management
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