VPC Connection Conditions

To enable communication between two regions via Cross Connect, it is necessary to configure the connection between two VPCs. For a successful connection between the two VPCs, certain conditions must be met; otherwise, the system will display an error and not allow the connection to be established.

The conditions for two VPCs to connect are:

No.	Conditions	Error Code
1	The two VPCs from different regions must not have overlapping CIDR blocks.	Overlaping cidr each others (code 2009)
2	Connecting two VPCs that already have an existing connection is not allowed. Even if creating a different Cross Connect, the connection cannot be established.	Existing a VPC Connect for this couple of VPCs (code 2010)
3	It is not allowed to create a VPC connection when a VPC in the Requester role has an existing connection with a VPC in the Accepter role that has overlapping CIDR blocks.	Existing a VPC Connection in Cross Connect opens from this CIDR (code 2011)
4	It is not allowed to create a VPC connection when a VPC in the Accepter role has an existing connection with a VPC in the Requester role that has overlapping CIDR blocks.	Existing a VPC Connection in Cross Connect opens to this CIDR (code 2013)
5	The two VPCs connected to each other must not be in the same region.	Not able to create VPC Connect in the same Region (code 2012)

Example of error codes when creating a VPC connection:

[Error Code 2010] An existing VPC connection pair already exists.

From the diagram, we can see that:

• At time T, the user can successfully create a connection from HCM-VPC01 to HAN-VPC01 between the two regions via Cross Connect 1.

• At time T+1, the system no longer allows the creation of a connection between HCM-VPC01 and HAN-VPC01, as this connection was previously established in the same Cross Connect.

• Creating a connection pair between HCM-VPC01 and HAN-VPC01 in a different Cross Connect at a later time (T+2) is also not possible, as the system will check whether the VPC pair already exists in another Cross Connect.

[Error Code 2011] Overlapping CIDR of a VPC connection in the Cross Connect at the Requester.

From the diagram, we can see that:

• At time T, the user can successfully create a connection from HCM-VPC02 to HAN-VPC01 between the two regions via Cross Connect 1.

• At time T+1, the system does not allow the creation of a connection from HCM-VPC03 to HAN-VPC03, due to the CIDR block 10.15.0.0/16 of HCM-VPC02 (which was previously connected to HAN-VPC01) overlapping with the CIDR of HAN-VPC03 that HCM-VPC03 is attempting to connect to.

[Error Code 2013] Overlapping CIDR of a VPC connection in the Cross Connect at the Accepter.

From the diagram, we can see that:

• At time T, the user can successfully create a connection from HCM-VPC01 to HAN-VPC02 between the two regions via Cross Connect 1.

• At time T+1, the system does not allow the creation of a connection from HCM-VPC03 to HAN-VPC03, because the CIDR block 10.14.0.0/16 of HAN-VPC02 (which was previously connected to HCM-VPC01) overlaps with the CIDR of HCM-VPC03 that is attempting to connect to HAN-VPC03.