Product Documentation

Communication in a Cluster Setup

Aug 31, 2016

The interfaces of NetScaler appliances that are added to a cluster, are prefixed with a node ID. This helps identify the cluster node to which the interface belongs. Therefore, the interface identifier c/u, where c is the controller number and u is the unit number, now becomes n/c/u, where n is the node ID. For example, in the following figure, interface 1/2 of node n1 is represented as 0/1/2, interface 1/1 of node n2 is represented as 1/1/1, and interface 1/4 of node n3 is represented as 2/1/4.

Figure 1. Interface naming convention in a cluster


Server communication
The cluster communicates with the server through the physical connections between the cluster node and the server-side connecting device. The logical grouping of these physical connections is called the server data plane.
Client communication
The cluster communicates with the client through the physical connections between the cluster node and the client-side connecting device. The logical grouping of these physical connections is called the client data plane.
Inter-node communication
The cluster nodes can also communicate with each other. The manner in which they communicate depends on whether the node exists on the same network or across networks.
  • Cluster nodes within the same network communicate with each other by using the cluster backplane. The backplane is a set of connections in which one interface of each node is connected to a common switch, which is called the cluster backplane switch. Each node of the cluster uses a special MAC address to communicate with other nodes through the backplane.
  • Across networks, steering of packets is done through a GRE tunnel and other node-to-node communication is routed across nodes as required.

The following figures shows the communication interfaces in L2 clusters and L3 clusters.

Figure 2. Cluster communication interfaces - L2 cluster


Figure 3. Cluster communication interfaces - L3 cluster