To measure the network performance between two monitoring agents, the agents must communicate together. When a monitoring session is created by a Network Monitoring Template, the system automatically selects one agent as the Client Agent and the other one as the Server Agent. The client sends a packet to the server every 500ms and the server replies back when it receives the packet. The measurement information is added inside the packet.

Client Selection Algorithm

The role selection is based on the Agent Modes and Agent Types.

Public Monitoring Agent

If one agent is a public monitoring agent, that agent will be set as the server because public monitoring agents cannot have the client role in a monitoring session. The other agent will automatically have the client role no matter what its agent mode is. If both agents are public monitoring agents, there will be an Invalid Session Error.

Client & Server Modes

If one agent has the client agent mode and the other one is a server, the selection is straightforward as long as the two agents can communicate together. If this is not the case, there will be an Invalid Session Error.

If a network monitoring session is created between two servers, the following selection algorithm will be used to determine which agent is client (the one that will initiate the connection) and which one is server (the one that will listen for incoming connections).

  1. If the two agents are not on the same network, the Private Server will be the client. If both servers are private servers, the session will not be created correctly and there will be an Invalid Session Error.
  2. If both agents are in the same network or if they are both Private Internet Server, the Client Selection Preference setting will be used. This setting is configured in the Agent Settings. The default value is 100 and the agent with the highest value will be selected at the client.
  3. If both agents have the same client selection preference, a random fonction will select the client and the server.

Invalid Session Errors

Invalid Session - Network Config Error

The two agents cannot communicate together because none of them has the Private Internet Server agent mode and they are not in the same network.

Invalid Session - No Server Error

If both agents are clients, the session will be created with the error: Invalid Session - No Server Error. At least one agent must be a server to have a valid monitoring session.

Invalid Session - Two Public Monitoring Agents

If both agents are Public Monitoring Agents, the session will be created with the error: Invalid Session - Two Public Monitoring Agents.

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