Avi Load Balancer SE Behavior on Gateway Monitor Failure

This section describes the issues that can occur and the Avi Load Balancer behavior in response to these issues when the gateway monitor is enabled using the UI or CLI.

Legacy high availability (HA) includes support for gateway monitoring. Avi Load Balancer SEs taking on either active or standby roles for a virtual service in a legacy HA deployment can perform gateway monitoring. By default, gateway monitoring is off until an IP address to monitor is furnished for the cloud. When an IP address is furnished, all legacy HA SE groups within the cloud perform gateway monitoring.

Note:

• Gateway monitoring for legacy HA is not supported for IPv6.

• If the external GW monitor fails, then the SEs are removed for any placement.

  • This is applicable for a single monitor in one VRF or other monitors that are succeeding.

Issue	Description
Gateway is not reachable from active Avi Load Balancer SE but is reachable from standby SE.	If only the standby Avi Load Balancer SE for a virtual service can reach the gateway, the active SE becomes standby, and the standby SE becomes active. When the gateway reachability is restored on the standby SE, it stays in the standby state.
Gateway is not reachable from standby Avi Load Balancer SE but is reachable from active SE.	The active Avi Load Balancer SE for the virtual service remains active, and the standby Avi Load Balancer SE remains in the standby state. When gateway reachability is restored on the standby SE, the SE stays in the standby state.
Active Avi Load Balancer SE loses gateway connectivity after standby SE has lost gateway connectivity.	The active Avi Load Balancer SE for the virtual service remains active, and the standby SE remains in the standby state.
Both the active Avi Load Balancer SE and the standby SE simultaneously lose gateway reachability.	The active Avi Load Balancer SE for the virtual service remains active and the standby SE remains in standby state. Note: Even when the gateway monitor shows that gateway connectivity is down, the Avi Load Balancer SEs remain operationally up.
With multiple gateway monitors, at least one gateway is not reachable from active Avi Load Balancer SE, but all gateways reachable from standby SE.	This results in switching all the virtual services on the current active SE to standby SE.