Describes the concepts of and benefits from using the network configuration of an RM system to establish connections with hosts behind protected networks.

Introduction

Because of security or some other reasons such as IP address depletion, some RM components can be located in private networks, usually NAT (Network Address Translator) protected. In this case the conventional RM communication mechanism either do not solve the problems when the involved hosts are accessed by client applications external to that network, or its obvious solution - static assignment of global IP addresses to those hosts, is not always suitable. Cross-network host placement is another possible configuration, but this case brings even more complications. RM network configuration management offers an application-level solution to this problem as well as gives an opportunity for optimization by using multiple network interfaces.

In an RM system the network configuration enables you to:

  • Separate application, client-side data flow from administration, server-side data flow.
  • Use several network interfaces for a single backend server host.
  • Assign specific communication schemes, network interfaces or port numbers in a single interface for use with particular backend hosts.
  • Introduce priority in connections that backend hosts use to communication with other hosts in a network.

Key Concepts

The RM network configuration is a part of the system configuration and can be modified in system configuration mode (see System Configuration). Applied network configuration is saved in the system database and updated on all backend hosts participating in the RM system.

The key points in network configuration management are networks, network filters and host network URLs.

Network

Each host in the RM system belongs to a certain network. There is at least one network - the default one. When a host is registered in the system with no network specified, it is automatically added to the default network.

Network Filters

A host can use filters defined for its home network to determine the network a connected host belongs to. A network filter has the following attributes:

  • ID - Uniquely identifies the network filter. The system automatically assigns an ID to each newly created network filter.
  • Source network - Represents the network the filter is defined for.
  • Destination network - Represents the external network the filter points to.
  • Priority - Indicates the importance of the filter in resolving the network of a host - the lower the priority, the higher the significance. Filter priorities determine the order in which the system will process a network's filters when matching them to a host IP address.
  • Net address - Represents the general address of the external network, for example 192.168.0.0. This attribute is used to determine the network to which a requesting host belongs.
  • Net mask - Represents the subnet mask for a host IP address.

A host is considered to belong to the destination network of a filter if the result from applying BITWISE AND to the host's IP address and the net mask is equal to the net address.

Network URL

A network URL represents address- and/or port-specific host URL defined for a particular network and communication scheme. A host has at least a URL in its home network and a "socket" URL the default network. For more information about host communication properties, refer to the Backend Server Host Configuration document.

Network Configuration Usage

When connected by an external application, a host (in particular a module running on it) can use the filters of its own network to determine the network of the caller application's host. Next, if needed the host can retrieve the URL defined for the caller's network of another host, and provide it to the caller. Therefore, the caller application will be able to establish a connection to the second host by using a valid URL.

Let's consider the situation where an RM system has three networks

  • CC_Network, holding the control center
  • RAS_Network holding all RAS hosts
  • and RAC_Network defined for potential RAC hosts and having no hosts (you cannot add a RAC host to a network as it is designed only to be able to connect and exchange data with an RM backend and does not run the modules of a fully-functional backend server).

For RAS_Network there is a filter with destination RAC_Network, net address 192.168.104.0 and net mask 255.255.255.0. For RAC_Network the control center owns a special network URL - 192.168.104.1.

When a RAC host with IP address 192.168.104.11 calls a RAS module to get the CC URL in the RAC's parent network, the system determines that the caller belongs to RAC_Network (BITWISE AND of 192.168.104.11 and 255.255.255.0 is equal to 192.168.104.0), the module gets the CC URL for RAC_Network and returns 192.168.104.1 to the RAC.

User Interface

You can define new networks, add hosts and filters to them and assign network URLs by using the console's System Configuration dashboard view, as described in Network Configuration User's Guide.

Network Configuration API

RM provides a front-end API for network configuration, i.e. for adding new networks, adding hosts to them, defining network filters and matching a host to a network filter. Refer to Network Configuration Management Programmer Guide for more details on the API usage.