ECS and RDS instances can communicate over an internal network only when both reside in the same network type. Identify your scenario below and follow the corresponding resolution.
Identify your scenario
| Scenario | ECS network type | RDS network type |
|---|---|---|
| Scenario 1 | VPC | Classic network |
| Scenario 2 | Classic network | VPC |
| Scenario 3 | VPC | VPC (different VPC) |
| Scenario 4 | VPC | VPC (same VPC, connection still fails) |
To check the network type of each instance, view the Network Type parameter on the instance details page in the console.
Scenario 1: ECS in VPC, RDS in classic network
Recommended: Migrate the RDS instance from the classic network to the Virtual Private Cloud (VPC) where the ECS instance resides. See Change the network type.
If migration is not feasible, use one of the following alternatives:
Purchase a new ECS instance in the classic network. Both instances then share the same network type. VPCs provide higher security than the classic network, so this is not a long-term recommendation.
ECS instances cannot be migrated from a VPC to the classic network.
Connect via the RDS public endpoint. No network changes are required, but this delivers lower performance, security, and stability than an internal network connection. To apply for a public endpoint, see the instructions for your database engine:
Scenario 2: ECS in classic network, RDS in VPC
Recommended: Migrate the ECS instance from the classic network to the VPC where the RDS instance resides. To find the VPC ID, click View Details to the right of the Network Type parameter on the RDS instance details page. See Migrate an ECS instance.
If migration is not feasible, use one of the following alternatives:
Change the RDS network type from VPC to classic network. Both instances then share the same network type. VPCs provide higher security than the classic network, so this is not a long-term recommendation.
Use ClassicLink to connect the classic-network ECS instance to the VPC-based RDS instance over an internal network without migrating either instance. See Enable ClassicLink.
If the connection still fails after enabling ClassicLink, see Troubleshoot connection issues between a classic network and a VPC after you establish a ClassicLink connection.
Connect via the RDS public endpoint. No network changes are required, but this delivers lower performance, security, and stability than an internal network connection. To apply for a public endpoint, see the instructions for your database engine:
Scenario 3: ECS and RDS in different VPCs
Recommended: Migrate the RDS instance to the VPC where the ECS instance resides. See Change the VPC and vSwitch.
If migration is not feasible, use one of the following alternatives:
Create a Cloud Enterprise Network (CEN) instance to establish connectivity between the two VPCs without moving either instance. See Use CEN to enable intra-region network communication.
Connect via the RDS public endpoint. No network changes are required, but this delivers lower performance, security, and stability than an internal network connection. To apply for a public endpoint, see the instructions for your database engine:
Scenario 4: Same VPC, but ping and telnet fail
If the ECS and RDS instances are in the same VPC and the same region, but the ECS instance can only reach RDS via the public endpoint — and both ping and telnet return failures — the issue is likely caused by routing. See What do I do if an ECS instance cannot connect to an ApsaraDB RDS instance due to routing problems?