Virtual border routers (VBRs) can connect data centers to Alibaba Cloud through Express Connect circuits. After you attach a VBR to a Cloud Enterprise Network (CEN) instance, you can use the health check feature of CEN to test the connectivity between a data center and Alibaba Cloud.

Background information

The health check feature sends multiple consecutive probe packets to the data center at a specific time interval. If response packets are returned, it indicates that the connection over the Express Connect circuit works as expected. If no response packet is returned after the health check feature sends multiple consecutive probe packets to the data center, the system determines that the connection over the Express Connect circuit is unhealthy. We recommend that you check the Express Connect circuit at the earliest opportunity. For more information, see Troubleshooting.

If your data center is connected to Alibaba Cloud through multiple VBRs, the system automatically switches traffic from the current VBR to a VBR that works as expected.

Configure health checks

  1. Log on to the CEN console.
  2. In the left-side navigation pane, click Health Check.
  3. On the Health Check page, select the region where the VBR that you want to manage is created and click Set Health Check.
  4. On the Set Health Check page, set the health check parameters and click OK.
    Parameter Description
    CEN Instances Select the CEN instance to which the VBR is attached.
    Virtual Border Router (VBR) Select the VBR that you want to monitor.
    Source IP

    You can use one of the following methods to configure the source IP address:

    • Automatic IP Address: The system automatically assigns an IP address from the 100.96.0.0/16 CIDR block. We recommend that you select this option.
    • Custom IP Address: You must specify an idle IP address from the 10.0.0.0/8, 192.168.0.0/16, or 172.16.0.0/12 CIDR block. The specified IP address must not be the same as the IP address with which you want to communicate, the IP address of the VBR on the Alibaba Cloud side, or the IP address on the user side.
    Destination IP The IP address of the VBR on the user side.
    Probe Interval (Seconds) The time interval at which probe packets are sent during the health check. Unit: seconds.

    Default value: 2. Valid values: 2 to 3.

    Probe Packets The number of consecutive probe packets that are sent during the health check.

    Default value: 8. Valid values: 3 to 8.

What to do next

  1. If your VBR uses static routes, you must add a static route to the on-premises device to which the Express Connect circuit is connected. Add the static route based on the following information:
    Set the destination CIDR block to the source IP address of health checks, set the mask length to 32, and set the next hop to the IP address of the VBR on the Alibaba Cloud side.
    Note If your VBR uses Border Gateway Protocol (BGP) routes, you do not need to add a route to the data center.
  2. Check whether the on-premises device to which the Express Connect circuit is connected can receive probe packets. Make sure that the on-premises device can return response packets as expected.
  3. We recommend that you set threshold-based alert rules for the Express Connect circuit. This allows you to receive alert notifications at the earliest opportunity when the health check feature detects connection interruptions. For more information, see Create a threshold-based alert rule for an Express Connect circuit.

More operations

Modify a health check

After you configure a health check, you can modify the source IP address, destination IP address, probe interval, and number of probe packets.

  1. Log on to the CEN console.
  2. In the left-side navigation pane, click Health Check.
  3. On the Health Check page, select the region where the VBR is created.
  4. Find the health check that you want to modify and click Edit in the Actions column.
  5. In the Edit Health Check dialog box, you can modify the source IP address, destination IP address, probe interval, and number of probe packets. After you modify the health check, click OK.

Delete a health check

If you no longer need to monitor the connectivity between the data center and Alibaba Cloud, you can delete the health check.

  1. Log on to the CEN console.
  2. In the left-side navigation pane, click Health Check.
  3. On the Health Check page, select the region where the VBR is created.
  4. Find the health check and click Delete in the Actions column.
  5. In the Delete Healthcheck message, click OK.

References