Duplicate IP Address alarm

Products

• VMware NSX

Issue/Introduction

Issue/Introduction :

• Title: Alarm for manager_health.duplicate_ip_address
• Event ID: manager_health.duplicate_ip_address

Alarm Description:

• Purpose: Detect duplicate IP addresses in a network
• Impact: Duplicate IP presence in a network would impact NSX Manager operations.
  
  
• You may see an alarm in the NSX Manager UI:
   
  
  
• The following error is observed in /var/log/upgrade-coordinator/upgrade-coordinator.log:
  <timestamp>  WARN pool-49-thread-2 UpgradeServiceImpl 4055 SYSTEM [nsx@6876 comp="nsx-manager" level="WARNING" subcomp="upgrade-coordinator"] [PUC] Pre-upgrade check InspectionTaskInfo[acknowledgement=false,componentType=MP,description=This check throws error if any of these alarms is in OPEN/ACKNOWLEDGED state: manager_health.duplicate_ip_address,manager_health.manager_config_disk_usage_very_high,password_management.password_expired,id=alarmCheck,name=Check for alarms which can have critical impact on upgrade of NSX Manager,needsAcknowledgement=false,needsResolution=false,resolution=false,resolutionError=<null>] failed with result BasicInspectionTaskResult{status=FAILURE, taskInfo=InspectionTaskInfo[acknowledgement=false,componentType=MP,description=This check throws error if any of these alarms is in OPEN/ACKNOWLEDGED state: manager_health.duplicate_ip_address,manager_health.manager_config_disk_usage_very_high,password_management.password_expired,id=alarmCheck,name=Check for alarms which can have critical impact on upgrade of NSX Manager,needsAcknowledgement=false,needsResolution=false,resolution=false,resolutionError=<null>], failureMessages=null, failures=[{"moduleName":"upgrade-coordinator","errorCode":30195,"errorMessage":"Found an active alarm for an event which can impact upgrade. Feature: Manager Health, Event Type: Duplicate IP Address, State: OPEN Node: ########-####-####-####-############. Please perform the recommended action for the alarm and ensure that the alarm is no longer active."}

Environment

VMware NSX-T Data Center
VMware NSX

Cause

The alarm is triggered because the NSX Manager nodes have detected a device using the same IP address as the NSX Manager nodes.

Resolution

Further investigation is required on the network to identify what is component is using the same IP of one of the NSX Manager nodes. A good tool to be used is the Arping, which is a scanner tool for ARP requests. Here is an example of how to use:

1. Access the NSX Manager node via SSH, which is suspected of having its IP address duplicated by a component on the network.
2. Run the following command:
   arping -D -I eth0 -c1 192.168.1.10   <- Duplicated IP
   
3. If the IP is NOT duplicated the response will be like the following:
   ARPING 192.168.1.10 from 0.0.0.0 eth0
Sent 1 probes (1 broadcast(s))
Received 0 reply (0 request(s), 0 broadcast(s))
   
   Note: This is the expected output as none virtual machine should be able to ARP its own IP
4. If the IP is duplicated the response sill be like the following:
   ARPING 192.168.1.10 from 0.0.0.0 eth0
Unicast reply from 192.168.1.10 [##::##:##:##:##]  1.398ms  <- This is the MAC, which is using the same IP
   Sent 1 probes (1 broadcast(s))
Received 1 response(s)
   
   
5. Once the MAC, which is using the same IP as the NSX Manager node, is identified, it is required to investigate which component has this MAC

Alternatively, use a different IP address for each conflicting network interface