doc-exports/docs/dds/umn/dds_faq_0013.html

What Should I Do If an ECS Cannot Connect to a DDS DB Instance?

Perform the following steps to identify the problem:

Replica Set Instance

1. Check whether the ECS and replica set instance are in the same VPC.
   • If yes, go to 3.
   • If no, configure the VPC peering connection. For details, see "VPC Peering Connection" in Virtual Private Cloud User Guide. Then, go to 2.

2. Check whether the client and replica set instance are deployed in different CIDR blocks and whether the CIDR block of the client is not 192.168.0.0/16, 172.16.0.0/24, or 10.0.0.0/8.
   • If yes, go to Configuring Cross-CIDR Access for Replica Set Instances and then go to 3.
   • If no, go to 3.

3. Check whether a security group has been associated with the ECS.
   • If yes, check whether the security group rules are suitable. For details, see Setting a Security Group. Then, go to 4.
   • If no, go to the VPC console from the ECS details page and click Security Groups to add a security group.

4. On the ECS, check whether the DDS instance address port can be connected.

   telnet <DB instance address> {8635}

   • If yes, the network is normal. Check the database username and password. For details, see Connecting to a Replica Set Instance Over Private Networks.
   • If the ECS still cannot connect to the instance port, contact technical support.

Cluster and Single Node Instances

1. Check whether the ECS and DDS instance are located in the same VPC.
   • If yes, go to 2.
   • If no, create an ECS in the VPC where the DDS instance is located.

2. Check whether a security group has been associated with the ECS.
   • If yes, check whether the security group rules are suitable. For details, see Setting a Security Group. Then, go to 3.
   • If no, go to the VPC console from the ECS details page and click Security Groups to add a security group.

3. On the ECS, check whether the DDS instance address port can be connected.

   telnet <DB instance address> {8635}

   • If yes, the network is normal. Check the database username and password. For details, see Connecting to a Cluster Instance Over Private Networks.
   • If the ECS still cannot connect to the instance port, contact technical support.

Parent topic: Database Connection