If your workloads require high availability (HA), you can use two Smart Access Gateway (SAG) devices when you design the network topology.
You can purchase two SAG devices to enable network HA when you connect a private network to Alibaba Cloud. The two SAG devices can be deployed in active-standby or active-active mode.
- Active-standby: One active device and one standby device. When an error occurs to the active device, you can switch network connections to the standby device. You must manually switch the standby device to the new active device in the console.
- Active-active: Two active devices. When an error occurs to one device, network connections are automatically switched to the other device.
SAG-100WM adopts active-standby mode by default. To request active-active mode, submit a ticket. SAG-1000 supports active-active mode only.
Device-based HA in inline mode
When you connect a private network to Alibaba Cloud, you can deploy two SAG devices in inline mode in your network and enable device-based HA. When an error occurs to one SAG device, network connections are automatically switched to the other device to avoid single point of failures (SPOFs). This improves network reliability.
Device-based HA in one-arm mode
To connect a private network to Alibaba Cloud, you can deploy two SAG devices in one-arm mode in your network and enable dynamic routing. This reduces system latency and improves network reliability.
After dynamic routing is enabled, SAG automatically learns and selects the optimal routes to local devices. Dynamic routing satisfies the needs of large-scale networks that require frequent networking changes and reduces operations and maintenance expenses.