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Cisco Bug: CSCsz22456 - 3.9 GSR PRP-2 lost NTP peer connection from time to time

Last Modified

Mar 09, 2018

Products (1)

  • Cisco 12000 Series Routers

Known Affected Releases


Description (partial)

After route processor fail over, the new active route processor may
keep repeating NTP synchronization and un-synchronization, e.g.

RP/0/0/CPU0:Apr 21 14:12:30.326 : ntpd[219]: %IP-IP_NTP-5-HP_CONN_RECOVERED : High priority NTP peer connection recovered - Stratum 15->2. 
RP/0/1/CPU0:Apr 21 14:17:54.236 : ntpd[219]: %IP-IP_NTP-5-SYNC_LOSS : Synchronization lost : DLRSC node : Peer unreachable or clock selection failed 
RP/0/0/CPU0:Apr 21 14:29:42.126 : ntpd[219]: %IP-IP_NTP-5-SYNC_LOSS : Synchronization lost : <ip add> : The clock was stepped and needs to be resynced 
RP/0/0/CPU0:Apr 21 14:29:42.126 : ntpd[219]: %IP-IP_NTP-5-HP_CONN_LOST : High priority NTP peer connection lost - Stratum 2->15. 
RP/0/0/CPU0:Apr 21 14:29:42.127 : ntpd[219]: %IP-IP_NTP-5-ALL_CONN_LOST : All NTP peer connections failed. 
RP/0/0/CPU0:BISCUIT-BR#RP/0/0/CPU0:Apr 21 14:35:03.210 : ntpd[219]: %IP-IP_NTP-5-HP_CONN_RECOVERED : High priority NTP peer connection recovered - Stratum 15->2. 

At the time of route processor failover, there is a case where the
route processor is still standby and is in the middle of learning the
clock frequency from the previous active route processor, i.e.,
adjusting its clock frequency to the correct one. The route processor
failover may disrupt the frequency adjustment process and results in
transient/inaccurate clock frequency. If there is a large frequency
difference between the transient one and the external NTP server's
one, the new active route processor encounters repetitive NTP
synchronization and un-synchronization.
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