APIX Gateway (GW) instances running on different machines can be set up as a cluster. 

Steps to set up multiple APIX GW instances as a cluster.

In the asg_core.cdd of each instance of APIX, the discovery-url has to be configured as follows:

<discovery-url>tcp://<machine1_ip>:6000;<machine2_ip>:6000/</discovery-url>

Note: 6000 is the by default "ASG" AS-metaspace port number.

==> Start each GW instance with -n (name) option.
Example: asg-engine -a <ProjectName> --propFile <tra_file> -p <full path of asg.properties> -c <cdd_file> -n APIXEngine1

==> To verify if your cluster is set up correct:
In the asg-caching-core-as.log, you will find "member joined" statements like below to the cluster "ASG":
----
[2017-02-07T10:19:41.036][12120][5448][INFO][ASG.$members] member joined: APIXEngine1 (a6ba32c-1770-5894d129-130, <machine1_ip>:6000)
[2017-02-07T10:19:41.036][12120][5448][INFO][ASG.$members] member joined: APIXEngine2 (a6ba335-1770-589a0fb2-302, <machine2_ip>:6000)
----