Intermittently Connected Agents over a Satellite Link

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This section presents the results in the scenario with agents connected over a satellite link, with agent bandwidth throttling.

Configuration

Twenty agents were installed in the management group. Each agents link to the MOM Management Server was set up with the following parameters to simulate a satellite link:

  • Available Bandwidth: 64 Kbps

  • Latency: 650 ms

  • Error Rate: Bit Error is 10 to the negative 6th

The scenario being tested was the "disconnected for 20 hours, connected for 4 hours" scenario. The agent queue size was increased to 60 MB to allow data to back up on the agent. This gets split three ways, with 20 MB each for the agent communication connector data queue, agent communication connector alert queue, and the agent workflow queue. Additionally, the agent bandwidth was throttled to 10 Kbps. Note that this is the bandwidth of the data before compression, and it is the compressed data that is sent over the wire. The compression ratio varies based on the type of data item and the batch size, but you can expect about 4:1. Therefore, if you want to use a bandwidth of 1 Kbps, set the agent throttled bandwidth to about 4 Kbps.

Results

The 20 agents were disconnected from the Management Server for 20 hours, during which operational data was being simulated on the agent. In these 20 hours, the agent communication connector data queue grew to 30% (of a possible 20 MB) on each agent. The other two 20-MB portions-the communication alert queue and the agent workflow queue-grew by less than 5%. When all the agents were reconnected at one time, all the backed-up data made it to the Management Server in 1 hours.