ECS4660-28F_Management Guide-R03

C HAPTER 24 | System Management Commands
Synchronous Ethernet
– 980 –
synce This command enables SyncE on all ports that support SyncE. Use the no
form to disable SyncE on all ports that support SyncE.
SYNTAX
[no] synce
DEFAULT SETTING
Disabled
COMMAND MODE
Global Configuration
COMMAND USAGE
◆ This command enables SyncE on ports 25-28. It does not configure any
of these port to be the clock source.
◆ SyncE must be enabled on a port before the clock selection method can
be set. Selection options include manual (synce ethernet clock-source),
automatic (synce auto-clock-source-selecting), or forced (synce force-
clock-source-selecting).
◆ SyncE frequency synchronization uses physical layer Ethernet to
distribute timing information. A synchronization chain is formed by
using a stratum 1 traceable source at one end which is then recovered
at downstream PHYs and retransmitted down the chain. Every node in
the chain must be capable of recovering and re-transmitting frequency
synchronization signals.
◆ SyncE provides timing synchronization through the physical layer, while
PTP (Precision Time Protocol) uses a higher level packet protocol which
can result in processing delays. However, both SyncE and PTP may be
used in combination to achieve a high level of frequency
synchronization with a common defined time.
◆ SyncE delivers a high level of frequency accuracy, but cannot deliver
time-of-day information (i.e., GMT). Conversely, PTP supports time-of-
day information required by billing and service level agreements.
◆ SyncE implementation guidelines are covered by these standards:
Table 86: Synchronous Ethernet Standards
Standard Description
ITU G.8264/Y.1364 Distribution of timing information through packet networks
ITU G.8261/Y.1361 Timing and synchronization aspects in packet networks
ITU G.8262/Y.1362 Timing characteristics of a synchronous Ethernet equipment slave
clock