This topic describes how to configure health checks on virtual border routers (VBRs) to monitor the health status of Express Connect circuits. When one of the Express Connect circuits is down, the other Express Connect circuit takes over.

Prerequisites

Your data center is connected to a virtual private cloud (VPC) through two Express Connect circuits. Multiple routes that point to the data center are added to the VPC for equal-cost multi-path routing (ECMP). For more information about how to configure ECMP, see Configure ECMP routing.

Background information

By default, after you configure health checks, Alibaba Cloud sends a probe packet every 2 seconds over the Express Connect circuits from the source IP address to the destination IP address in the data center. If no responses are returned for eight consecutive probe packets over one of the Express Connect circuits, the other Express Connect circuit takes over.

Note If CoPP policies or anti-attack policies are configured for the network device in the data center, such as a Cisco device,probe packets may be dropped. As a result, the system may frequently switch between the two Express Connect circuits. We recommend that you disable throttling for the network device in the data center.
Configure health checks

Procedure

  1. Log on to the Express Connect console.
  2. In the top navigation bar, select the region and choose VPC Peering Connections > VBR-to-VPC in the left-side navigation pane.
  3. On the VBR-to-VPC page, find the peering connection that you want to manage and choose More > Health Check.
  4. On the Health Check page, click Configure, set the following parameters, and click OK.
    Parameter Description
    Source IP Enter an idle private IP address from the VPC.
    Destination IP Enter the private IP address of the interface on the network device in the data center.
    Probe Interval (Seconds) Specify the interval at which probe packets are sent for a health check. Unit: seconds.

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

    Probe Packets Specify the number of probe packets to be sent for a health check. Unit: packets.

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

What to do next

You can clear the health check settings.

  1. Log on to the Express Connect console.
  2. In the top navigation bar, select the region and choose VPC Peering Connections > VBR-to-VPC in the left-side navigation pane.
  3. On the VBR-to-VPC page, find the peering connection that you want to manage and choose More > Health Check.
  4. On the Health Check page, click Clear. In the Clear Health Check Settings message, click OK.