Cisco ASR1006 Configuration Guide - Page 346

Restrictions and Usage Guidelines Network Synchronization Support QL-Enabled Mode In QL-enabled mode, the following parameters contribute to the selection process: • Quality level • Signal fail via QL-FAILED • 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 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 and Usage Guidelines This section lists the restrictions and usage guidelines for configuring network synchronization on a router: • See Table 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 router. You cannot change the synchronous mode on a per-interface basis. • You can configure up to eight ports as clock sources on the router. • The SyncE feature is SSO-coexistent, but not SSO-compliant. The clock selection algorithm is restarted on a switchover. During the switchover, the router goes into holdover mode. • The SyncE interfaces in 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. • It is recommended that you do not configure multiple input sources with the same priority as this impacts the TSM (Switching message delay). • You cannot implement the network-clock based clock selection algorithm and the new algorithm simultaneously. Both these algorithms are mutually exclusive. • The Line to External feature for the clock cleanup is supported only if the line interface and the external interface are on the same metronome SPA. Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide 6