Guest

Preview Tool

Cisco Bug: CSCvv34333 - NTP is unable to synchronise even when NTP messages are exchanged

Last Modified

Aug 25, 2020

Products (1)

  • Cisco IOS

Known Affected Releases

15.9(3.0t)M1

Description (partial)

Symptom:
NTP messages are received but router just ignore packets
Stops working after about 5 minutes

Conditions:
configuration is below:

ip-cosg-ch-bsg-mr-007#show run | section ntp
ntp authentication-key 1 md5 <password>
ntp authenticate
ntp trusted-key 1
ntp source Loopback0
ntp update-calendar
ntp server 172.28.5.22 prefer
ntp server 172.28.5.23

Connection to NTP server prefer is working with no drops:

ip-cosg-ch-bsg-mr-007#ping 172.28.5.22 source lo0 rep 1000
Type escape sequence to abort.
Sending 1000, 100-byte ICMP Echos to 172.28.5.22, timeout is 2 seconds:
Packet sent with a source address of 172.29.191.123
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Success rate is 100 percent (1000/1000), round-trip min/avg/max = 20/38/132 ms
ip-cosg-ch-bsg-mr-007#

Confirmed same NTP server is working with other NTP clients.
Bug details contain sensitive information and therefore require a Cisco.com account to be viewed.

Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
  • Severity
  • Known Fixed Releases
  • Related Community Discussions
  • Number of Related Support Cases
Bug information is viewable for customers and partners who have a service contract. Registered users can view up to 200 bugs per month without a service contract.