If you have a WebSphere MQ Publish/Subscribe broker network, you can continue to use this network unchanged. The introduction of WebSphere Message Broker to your environment, and the creation of brokers in that broker domain, does not affect your WebSphere MQ Publish/Subscribe broker domain until you take specific action to connect the two networks.
If you want to have two separate, independent networks, you do not have to do anything. You can retain your existing WebSphere MQ Publish/Subscribe network, and install and configure a WebSphere Message Broker network, without any interaction.
A heterogeneous network is a network of brokers, some of which form a WebSphere MQ Publish/Subscribe network and some of which belong to the WebSphere Message Broker product.
With the WebSphere Message Broker product, there are two ways in which a broker can be joined to the WebSphere MQ Publish/Subscribe network; it can be joined as a leaf node or as a parent node.
When a broker is joined as a leaf node, it is joined as a child broker of another broker in the WebSphere MQ Publish/Subscribe network.
Adding the broker as a leaf node rather than as a parent node causes the new broker to receive only some of the WebSphere MQ Publish/Subscribe message traffic that is directed to the brokers for which this new broker is a child broker.
When a broker is joined as a parent node, it is joined as a parent broker of one or more brokers in the WebSphere MQ Publish/Subscribe network.
Adding the broker as a parent node rather than as a leaf node causes the new broker to receive all the WebSphere MQ Publish/Subscribe message traffic that is directed to the child brokers for which this new broker is the parent broker.