What Can I Do If Cross-Region Network Communications Fail?

After you complete all the required configuration, you can use ICMP or Telnet to test network connectivity. If network communications fail, do the following to locate the fault:

• Check whether the security group containing the ECSs in the destination VPC allows ICMP or Telnet traffic over the corresponding port in the inbound direction. If ICMP or Telnet traffic is not allowed, the packets will be blocked by the security group.
• Check whether a network ACL is configured for the subnet in the destination VPC to deny the communications between the source and destination VPCs. If such an ACL exists, the packets will be blocked by the ACL.
• Check whether there are overlapping subnets in the source and destination VPCs. If they have overlapping subnets, the packets will not be sent to the subnet of the destination VPC.
• Check whether an inter-region bandwidth is assigned between source and destination regions. If you have a bandwidth package but there is no inter-region bandwidth between different regions, the default 10 kbit/s of bandwidth may fail to transmit large ICMP packets or Telnet packets.