NSX Manager detecting duplicate of its own IP

Products

• VMware NSX for vSphere

Issue/Introduction

Symptoms:

• NSX Manager detecting duplicate of its own IP with MAC.
   
• There are actually no duplicates in the environment.
   
• In the NSX Manager system events, alerts are seen similar to below:
  
  Detect_Duplicate_NSXIP: .! 50% packet loss
Detect_Duplicate_NSXIP: output of arping command 0
Detect_Duplicate_NSXIP: Duplicate IP Detected
fcron[25252]: Job '/blue_lane/bin/ntpsync.pl' completed
Detect_Duplicate_NSXIP: The following mac has the same IP as NSX Manager
Detect_Duplicate_NSXIP: Sending MAC Address
   
• In the /var/log/messages file, alarms are seen every day similar to:
  
  [var/log]# egrep -R -i "is duplicate" *
messages:2017-02-16T18:05:00+00:00 #### Detect_Duplicate_NSXIP: Detecting If the NSX manager IP #.#.#.# is duplicate

 

Environment

VMware NSX for vSphere 6.4.x
VMware NSX for vSphere 6.3.x
VMware NSX for vSphere 6.2.x

Cause

This issue occurs when the arp command starts responding for the NSX Manager IP though the IP is not assigned to any other machine in the network. Therefore, NSX Manager starts sending a false alarm indicating that the NSX Manager IP is duplicated in the network.

Resolution

This issue is resolved in:

• VMware NSX for vSphere 6.2.7.
• VMware NSX for vSphere 6.3.5. 
• VMware NSX for vSphere 6.4.1.

Workaround:
To workaround the issue, complete these steps:

1. Log in to the NSX Manager.
    
2. Run the vi /etc/fcrontab command and comment out DetectDuplicateNSXIP.sh script line by adding # in front of the line.
   
   [root@/var/log]# cat /etc/fcrontab
PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/java/jre/bin/:/blue_lane/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin:
/usr/local/sbin:/usr/sbin:/sbin:/usr/ant/bin:/usr/local/mysql/bin:/opt/vmware/vpostgres/current/bin
@ 1 /usr/sbin/logrotate /etc/logrotate.conf
@ 1 /blue_lane/bin/ntpsync.pl
10 0 * * * secureall /home/secureall/secureall/sem/WEB-INF/classes/RunAIPurge.sh -p 2>&1 | /usr/bin/logger -t Run_AI_Purge
*/5 * * * * /blue_lane/bin/rabbitstatus.sh >> /var/log/rabbitstatus.log
#* */3 * * * /blue_lane/bin/DetectDuplicateNSXIP.sh 2>&1 | /usr/bin/logger -t Detect_Duplicate_NSXIP
    
3. Reload the new configuration to cron by running this command:
   
   >fcrontab /etc/fcrontab

2017-02-17T10:57:32+00:00 fcrontab[22653]: installing file /etc/fcrontab for user root
2017-02-17T10:57:32+00:00 fcronsighup[22654]: Conf file (/usr/local/etc/fcron.conf) must be owned by root:fcron and (no more than) 644 : ignored
2017-02-17T10:57:32+00:00 fcron[3528]: updating configuration from /usr/local/varr/pool/fcron
2017-02-17T10:57:32+00:00 fcron[3528]: adding new file root"
2017-02-17T10:57:38+00:00 fcron[23251]: Job '/usr/sbin/logrotate /etc/logrotate.conf' started for user root (pid 23252)
2017-02-17T10:57:38+00:00 fcron[23253]: Job '/blue_lane/bin/ntpsync.pl' started for user root (pid 23254)
2017-02-17T10:57:40+00:00 fcron[23251]: Job '/usr/sbin/logrotate /etc/logrotate.conf' completed