Cisco 3845 - Security Bundle Router - Page 132

6-4
Cisco ME 3800X and 3600X Switch Software Configuration Guide
OL-23400-01
Chapter 6 Configuring Synchronous Ethernet
Understanding SyncE
Figure 6-2 Broken Network Link
Figure 6-3 shows how the REP segment handles the broken link to avoid timing loops in the SyncE
network.
Figure 6-3 SyncE REP Segment
When you configure the SyncE REP workaround, you can configure these SyncE features:
• Hold-off timeout—If a clock source goes down, the switch holds the fail signal for a specific time
period before removing the source and restarting the synchronization process. Configure the
hold-off timeout by entering the network-clock-select hold-off timeout global configuration
command.
• Wait-to-restore timeout—If a failed SyncE source comes up, the switch waits for a specific time
period of time before considering the source as available in the selection process. The default time
is 300 seconds. Configure wait-to-restore timeout by entering the network-clock-select
wait-to-restore global configuration command.
281357
Blocked
REP Edge
Port
REP Edge
Port
Clock
Reference
Switch 3
Switch 4
Switch 2
Switch 1
Router 2
Router 1
Priority 1
Priority 1
Priority 1
Priority 1
Priority 2
Priority 2
Priority 2
Priority 2
Data path
Timing path
281358
REP Edge
Port
REP Edge
Port
Clock
Reference
Switch 3
Switch 4
Switch 2
Switch 1
Router 2
Router 1
Priority 1
Priority 1
Priority 1
Priority 1
Priority 2
Priority 2
Priority 2
Priority 2
Data path
Timing path