Network interface controllers
You need to consider the number of network interface controllers (NICs) that you require when you configure your environment. You should consider factors including the class of traffic, volume of traffic, and the type of environment that you are using when planning the number of NICs that you need.
Environment considerations
If you are configuring a development or test environment, a minimum of one NIC is required.
In production environments, use a dedicated network interface for all classes of light traffic. These classes are shown in the following table as Admin, HA discovery, cluster control, and cluster discovery traffic. You might want to consider additional network interfaces depending on the workload and the use of IBM® Watson IoT Platform - Message Gateway HA and clustering features. For client traffic and cluster messaging traffic, use an additional dedicated NIC.
If you are configuring HA in a production environment, you can use either two unbonded NICs or one highly available NIC. If you are using IBM Watson IoT Platform - Message Gateway HA with reliable messaging (QoS > 0), use an additional dedicated NIC for HA replication traffic. In HA environments, this configuration is required to minimize the risk of a split brain condition. Split brain can occur in an HA environment if the primary node that provides messaging operations detects that the other server is acting as a primary. For more information about link aggregation, see the documentation for your operating system.
Traffic class considerations
The following table describes the major classes of traffic and the traffic load:
| Class of traffic | Description | From MQTT |
|---|---|---|
| Admin | The network traffic between the Message Gateway Admin endpoint and administrative clients. For example, REST client or IBM Watson IoT Platform - Message Gateway Web UI. | Light |
| Client | The network traffic between Message Gateway server and clients. | Heavy |
| HA replication | The network traffic used for state replication between the ACTIVE and STANDBY members of an HA pair. | Heavy - if using QoS > 0 for reliable messaging. |
| HA discovery | The network traffic used for discovery and heart-beating between the ACTIVE and STANDBY members of an HA pair. | Light |
| Cluster messaging | The network traffic used for forwarding client data between members of a Message Gateway cluster. | Heavy |
| Cluster control | The network traffic used for propagating cluster state information between members of a Message Gateway cluster. | Light |
| Cluster discovery | The network traffic used for discovering new cluster members. | Light |
Multiple heavy traffic classes can be combined on a single network interface - for example a single highly available bonded interface. However, you must consider the packet rate limitations of the OS NIC driver when planning the number of NICs that you require.