One way to buildout a network for a Hadoop cluster is to provide a VLAN for cluster traffic and another VLAN for management/external integration. In this case, the cluster VLAN is NOT available outside the cluster or datacenter. And the only way to interact with the cluster is by the management VLAN.
A Hadoop cluster is designed to work on a single VLAN. The hosts can have multiple IP addresses, but the cluster will only operate on one of them. With the management interfaces bound to the cluster network, they aren't reachable through the management VLAN. In this case, one solution is to use 'iptables' to route requests between the hosts interfaces.