Filter
Top Products
11-7
Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide
OL-16506-17
Chapter 11 Network Synchronization Support
Restrictions for Network Synchronization
• Priority
• External commands.
If no external commands are active, the algorithm selects the reference (for clock selection) with the
highest QL that does not experience a signal fail condition. If multiple inputs have the same highest QL,
the input with the highest priority is selected. For multiple inputs having the same highest priority and
QL, the existing reference is maintained (if it belongs to the highest priority and QL group). Otherwise,
an arbitrary reference from the highest priority and QL group is selected.
QL-Disabled Mode
In QL-disabled mode, the following parameters contribute to the selection process:
• Signal failure
• Priority
• External commands
If no external commands are active, the algorithm selects the reference (for clock selection) with the
highest priority that does not experience a signal fail condition. For multiple inputs having the same
highest priority, the existing reference is maintained (if it belongs to highest priority group). Otherwise,
an arbitrary reference from highest priority group is selected.
Restrictions for Network Synchronization
This section lists the restrictions for configuring network synchronization on a router. See Table 11-3 for
a listing of the SPAs that you can use when configuring network synchronization.
• If the network clock algorithm is enabled, use the system clock as the Tx clock (synchronous mode)
for the Ethernet interfaces of the corresponding router. You cannot change the synchronous mode
on a per-interface basis.
• You can configure up to eight ports as clock sources on a router.
• The SyncE feature coexists with SSO, but is not SSO-compliant. The clock selection algorithm is
restarted on a switchover. During switchover, the router goes into holdover mode.
• The SyncE interfaces in the WAN mode cannot be used for QL-enabled clock selection. You must
either use them with the system in QL-disabled mode, or disable the ESMC on the interfaces, and
use them as QL-disabled interfaces.
• We recommend that you do not configure multiple input sources with the same priority because this
impacts the T
SM
(switching message delay).
• You cannot implement the network clock-based clock selection algorithm and the new algorithm
simultaneously. Both these are mutually exclusive.
• The Line to External feature for clock cleanup is supported only if the line interface and the external
interface are on the same metronome SPA.
Note The Line to External feature is not supported on the Cisco ASR 1002-X Router.