12.4. Avoid IP address conflicts on the Provisioning network

Discovery and deployment tasks will fail if the destination hosts are allocated an IP address which is already in use. To avoid this issue, you can perform a port scan of the Provisioning network to determine whether the discovery IP range and host IP range are free.
Perform the following steps from the Undercloud host:

Procedure 12.5. Identify active IP addresses

  1. Install nmap:
    # yum install nmap
    
  2. Use nmap to scan the IP address range for active addresses. This example scans the 192.0.2.0/24 range, replace this with the IP subnet of the Provisioning network (using CIDR bitmask notation):
    # nmap -sn 192.0.2.0/24
    
  3. Review the output of the nmap scan:
    For example, you should see the IP address(es) of the Undercloud, and any other hosts that are present on the subnet. If any of the active IP addresses conflict with the IP ranges in undercloud.conf, you will need to either change the IP ranges or free up the IP addresses before introspecting or deploying the Overcloud nodes.
    # nmap -sn 192.0.2.0/24
    
    Starting Nmap 6.40 ( http://nmap.org ) at 2015-10-02 15:14 EDT
    Nmap scan report for 192.0.2.1
    Host is up (0.00057s latency).
    Nmap scan report for 192.0.2.2
    Host is up (0.00048s latency).
    Nmap scan report for 192.0.2.3
    Host is up (0.00045s latency).
    Nmap scan report for 192.0.2.5
    Host is up (0.00040s latency).
    Nmap scan report for 192.0.2.9
    Host is up (0.00019s latency).
    Nmap done: 256 IP addresses (5 hosts up) scanned in 2.45 seconds