Search Engine: Elastic

Article ID: 132152, created on Jan 29, 2018, last review on Jan 29, 2018

  • Applies to:
  • Operations Automation

Symptoms

All websites hosted on an Apache NG cluster and running on a particular IP (for example, 203.0.113.2) are unavailable from the external network. A web browser is unable to connect to the websites. Connections on the port 80 of the IP address are not accepted.

At the same time, the websites running on other shared IP addresses are available. All web servers are available from the Load Balancer and accept connections on the http/https ports.

Cause

The IP address in question is assigned to more than one load balancer:

If trying to disable the corresponding interafce:

[root@HELB01 ~]# ifdown eth0:5

and than activate it again - it fails with the below error:

[root@HELB01 ~]# ifup eth0:5
Error, some other host already uses address 203.0.113.2.

Resolution

  1. Find the MAC address of the host which has the IP address assigned:

    [root@HELB01 ~]# ping 203.0.113.2
    PING 203.0.113.2 (203.0.113.2) 56(84) bytes of data.
    64 bytes from 203.0.113.2: icmp_seq=1 ttl=64 time=1.45 ms
    
    [root@HELB01 ~]# arp 203.0.113.2
    Address                  HWtype  HWaddress           Flags Mask            Iface
    203.0.113.2              ether   00:50:56:8E:2A:14   C                     eth0
    
  2. Remove the IP address from the host with the found MAC address
  3. Activate the corresponding interface of the Load Balancer:

    [root@HELB01 ~]# ifup eth0:5
    

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