IV26715: FALSE PING FAIL EVENTS GENERATED WHEN NTP CLOCK ADJUSTMENTS ARE MADE.

IBM Tivoli Network Manager IP 3.9.0 Fix Pack 3, 3.9.0-TIV-ITNMIP-FP0003

APAR status

• Closed as program error.

Error description

• Product: Tivoli Network Manager
  Version: 3.8
  Component: Poller
  
  Symptoms:  Very fast responses can appear to the poller to
  arrive before the request is sent, resulting in ping fail events
  where no such outage exists.
  
  When ITNM is processing very fast ping responses (in the order
  of millisecs) occasionally an anomaly occurs with the
  timestamps used for send/receive packets. The effect of this
  currently is that the rtt appears negative and a timeout is
  incorrectly triggered.
  
  Debug messages were introduced into the poller to log when this
  was occuring.  The timings of these messages can then be
  compared to the NTP daemon log file for adjustments in the NTP
  clock.
  
  A defensive test fix was created to recognise these conditions
  and prevent the false ping from being generated.
  
  Example of poller log message and NTP daemon log message
  
  Poller:
  2012-08-09 15:27:27 INFO     CPingCache.cc(53): Ping return time
  too small, setting to zero:  IP.IP.IP.IP 5280381 -1
  
  NTPD:
  Thu Aug  9 15:27:26 JST 2012
  sendpkt(fd=5 IP.IP.IP.IP,IP.IP.IP.IP, ttl=-8, 48)
  input_handler: fd=5 length 48 from 0aef00a8
  clock_filter(IP.IP.IP.IP, -0.061943, 0.00024, 0.00002)
  clock_update(IP.IP.IP.IP)
  select: prefer offset -0.061943
  Thu Aug  9 15:27:27 JST 2012
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All ITNM 3.9 Poller users.                                   *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * FALSE PING FAIL EVENTS GENERATED WHEN NTP CLOCK ADJUSTMENTS  *
  * ARE                                                          *
  * MADE.                                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * fix pack | 3.9.0-ITNMIP-FP0003                               *
  * fix pack | 3.8.0-ITNMIP-FP0007                               *
  ****************************************************************
  

Problem conclusion

• Added code to fix problem when NTPD adjusts the clock.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  TIV NETWK MGR I

• Fixed component ID

  5724S4500

Applicable component levels

• R380 PSN

     UP

• R380 PSY

     UP

• R390 PSN

     UP

• R390 PSY

     UP

• R401 PSN

     UP

• R401 PSY

     UP