Load Balancing Gateway considerations

Network Discovery uses the IP and MAC address of the default gateway to identify networks. In environments using load balancing gateways, this can cause issues with network identification and monitoring.

Why this matters

In a load-balanced setup, multiple routers with different MAC addresses may respond to the same virtual gateway IP address. When the load balancer switches to a different router, the MAC address associated with the gateway IP changes. This causes Network Discovery to treat the network as a new, unmanaged network, and the previously managed network may be incorrectly reported as offline.

If the new MAC address is then managed, it too will be marked offline the next time the load balancer switches, creating a cycle of false offline alerts and duplicate network entries.

How to configure load balancing gateways

To ensure consistent network monitoring:

  1. Bypass the load balancer on at least one high-availability device by configuring its default gateway to point directly to a specific router. This ensures the IP and MAC address remain stable.
  2. Apply the same gateway configuration to multiple devices. This provides redundancy in case one device becomes unavailable.
  3. Enable Network Discovery only on these specifically configured devices.
  4. Disable Network Discovery on all other devices that still use the load-balanced gateway. This prevents them from becoming the Primary Network Discovery Agent and causing inconsistent network identification.

To apply this configuration successfully:

  1. Unmanage a network to remove it from Network Discovery.
  2. Manage Network Discovery on all devices currently acting as Network Discovery Agents. Check settings at the Device type, Client, Site, and individual device levels.
  3. Manage Network Discovery only on the devices with the updated gateway configuration.
  4. Manage a network again.

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