This blog covers the multicast traffic considerations with multiple IBM Business Process Manager (BPM) V8.5 environments in a flat network. It also covers the steps that must be taken to address these considerations.
For the sake of this discussion, we can assume that a customer is on a WebSphere Application Server Network Deployment V8.5.x.x (WAS ND) and a BPM Standard V8.5 two node three cluster topology.
Multicast is a technique for one-to-many communications over an IP infrastructure in a network, where a host can send data to a group of hosts without knowing who are the members of the group. In WAS ND, the multicast address is used by the BPM cluster members (application, support and messaging) and node agents to discover one another on startup. This multicast address is a logical address, therefore it is not bound to any physical address and will not be the same as the host name (or IP address) of the host on which the node agent is executed. In WAS ND, multicast host addresses must be within a special range (126.96.36.199 to 188.8.131.52) defined by the IP standards and must never carry a host name value. The default value for the WebSphere node agents is 184.108.40.206.
By default, all BPM environments (Development, Test, Production etc) installed in a flat network come with a multicast address of 220.127.116.11. This means that in a flat network, multicast messages from cluster members and node agents in one environment will also be routed to members of the other environments. This may lead to unintended consequences. To mitigate this issue, a unique multicast address must be assigned to each BPM environment. The example below shows the steps involved to assign a multicast address of 18.104.22.168 to a WAS ND cell in a BPM environment during the product installation and deployment environment configuration phase.
- Install the BPM product binaries.
- Create the BPM Deployment environment.
- Start the Deployment Manager.
- Update the multicast address in the <dmgrprofile_home>/config/cells/<cell>/nodes/<node>/serverindex.xml file. For example; in a BPM environment with Deployment Manager profile devdmgr, and node profiles devbpmnode1 and devbpmnode2, update the following files:
In the serverindex.xml file, update the host IP address associated with port NODE_MULTICAST_DISCOVERY_ADDRESS to an agreed IP address (22.214.171.124) for the given environment:
<specialEndpoints xmi:id="NamedEndPoint_1395187836459" endPointName="NODE_MULTICAST_DISCOVERY_ADDRESS">
<endPoint xmi:id="EndPoint_1395187836462" host="126.96.36.199" port="5000"/>
- Carry out a full synchronization using the administrative console: System Administration -> Save changes to master repository -> Enable Synchronize Changes with Nodes -> Save.
- Restart the node agents and the Deployment Manager.
- Start the cluster members and ensure a successful startup.
To change the multicast address in an existing BPM environment, follow steps 4, 5,6 and 7 above.