EAP could be configured to act as an Undertow mod_cluster Proxy load balancer. There is a advertising feature that enables the balancer to advertise its location on the network to a set UDP Multicast interface. Worker nodes, other EAP instances, could listen to the advertised messages and contact the balancer on its location. This functionality is not supported in Microsoft Azure due to UDP Multicast limitations.

In order to be able to contact the balancer, worker nodes must have balancer's address set thus (set on worker):

• /socket-binding-group=standard-sockets/remote-destination-outbound-socket-binding=proxy-one:add(host="BALANCER_ADDRESS", port="BALANCER_PORT")
• /subsystem=modcluster/mod-cluster-config=configuration:write-attribute(name=proxies,value=[proxy-one])

Note:

• BALANCER_ADDRESS and BALANCER_PORT are the address and port the EAP Undertow mod_cluster Proxy listens to mod_cluster protocol messages, e.g. management-socket-binding=http attribute in Undertow subsystem, mod_cluster filter.
• proxy-one name is arbitrary
• one can set multiple balancers for one worker and the worker will contact them all

Book: https://access.qa.redhat.com/documentation/en/red-hat-jboss-enterprise-application-platform/7.0/single/using-jboss-eap-on-microsoft-azure/#supported_configurations