HAProxy ALOHA Documentation 13.5


When load balancing UDP-based services via the LB Layer4 tab, you can health check your servers by using the Address Resolution Protocol (ARP) to check whether a server with a given IP address exists on the network.

Enable ARP checks

When you set up ARP health checks, HAProxy ALOHA regularly broadcasts an ARP request to all devices on the network to verify that a server with a given IP address exists. If a matching server does not reply, the health check fails.

Check whether the two Syslog servers exist on the network.

director syslog_servers UDP
  balance roundrobin                      # load balancing algorithm
  mode gateway                            # forwarding mode

  option arpcheck
  check interval 5s timeout 1s            # advanced check parameters
  server syslog1 check
  server syslog2 check
  1. Select the LB Layer4 tab.

  2. Add a check parameter to each server line for which you would like to enable health checking.

  3. Add option arpcheck in the same section. It uses the following syntax:

    option arpcheck [iface <name>]

    This directive takes the following arguments:

    iface <name> (optional)

    Network interface to use when sending the ARP request.

  4. Add the line check to the section to configure other options. It uses the following syntax:

    check { [timeout <seconds>] [interval <seconds>] [source <ip>] [port <port>]
            [rise <count>] [fall <count>] [inhibit] }

    timeout <seconds>

    Period after which an attempt without a response from the server is considered as failed (default: half of interval)

    interval <seconds>

    Interval between two checks, in seconds (default: 10 seconds)

    source <ip>

    Source IP to use when performing the check

    port <port>

    Forces the destination port (default: real server port, if it exists)

    rise <count>

    A server will be considered as operational after <count> consecutive successful health checks. The default is 1.

    fall <count

    A server will be considered as dead after <count> consecutive unsuccessful health checks. The default is 1.


    If a server is down, its weight is passed to 0 but not deleted. Established connection are not broken but new connections are dispatched on the other servers.

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