Connect multiple VPCs using Transit Gateway

KakaoCloud allows centralized traffic management between VPCs using Transit Gateway.

info

• Estimated time: 60 minutes
• User environment
  • Recommended OS: MacOS, Ubuntu
  • Region: kr-central-2
• Prerequisites
  • VM access key pair
  • Project Admin permissions

About this scenario

In this scenario, you will create two VPCs and connect them using Transit Gateway. The steps include:

1. Create two VPCs. Each VPC uses one AZ and the default public subnet.
2. Create a Transit Gateway and attach both VPCs to it.
3. Configure static routing in Transit Gateway to direct traffic to each VPC based on CIDR blocks.
4. Configure subnet route tables to route traffic through Transit Gateway to reach the destination VPC.
5. Create VM instances in each subnet and verify connectivity using the ping command.

The scenario architecture is illustrated below:

Getting started

Step 1. Create VPC and subnets

VPCs provide logically isolated virtual network spaces, enabling flexible resource management on KakaoCloud. For more details, refer to the VPC documentation.

1. Go to KakaoCloud Console > VPC and click [Create VPC].

2. Create vpc-a using the following settings:

   

   Item	Sub-item	Value
   VPC Information	VPC Name	handson-vpc-a
   VPC IP CIDR Block		10.1.0.0/16
   Availability Zone	Number of AZs	1
   	First AZ	kr-central-2-a
   Subnet Configuration	Number of public subnets per AZ	1
   	Number of private subnets per AZ	0

3. Create vpc-b using the following settings:

   caution

   Ensure the CIDR ranges of each VPC do not overlap. For example, if vpc-a uses 10.1.0.0/16, then vpc-b must use a distinct range like 10.2.0.0/16. Overlapping CIDR blocks will prevent communication between VPCs.

   

   Item	Sub-item	Value
   VPC Information	VPC Name	handson-vpc-b
   	VPC IP CIDR Block	10.2.0.0/16
   Availability Zone	Number of AZs	1
   	First AZ	kr-central-2-b
   Subnet Configuration	Number of public subnets per AZ	1
   	Number of private subnets per AZ	0

4. Go to KakaoCloud Console > VPC > Subnets and verify the created network resources.

Step 2. Create and configure Transit Gateway

Transit Gateway simplifies the complexity of managing multiple VPC Peering connections by providing centralized traffic management for inter-VPC and VPC-to-on-premises traffic. For more details, refer to the Transit Gateway documentation.

1. Create Transit Gateway

1. Go to KakaoCloud Console > Transit Gateway and click [Create Transit Gateway].

2. Enter the following settings for the Transit Gateway:

   

   Item	Description
   Transit Gateway Name	handson-transit-gateway
   Default Association	Enabled

3. Verify that the resource has been created successfully.

   

2. Create attachments

1. Access the Attachment creation settings from the details page of the created Transit Gateway.

   

2. Add handson-vpc-a as an Attachment to the Transit Gateway.

   

3. Add handson-vpc-b as an Attachment to the Transit Gateway.

   

4. Verify that the Attachments have been added successfully.

   

3. Configure Transit Gateway routing

1. Access the Routing Table Details page connected to the Transit Gateway.

   Go to KakaoCloud Console > Transit Gateway > Transit Gateway List Table, or navigate to KakaoCloud Console > Transit Gateway > Route Table.

   

2. In the Route tab, you can view static routes. Click [Add Static Route] to add a new route.

   

3. Add a static route to direct traffic with the destination 10.1.0.0/16 to handson-vpc-a.

   

   Item	Value
   Destination	10.1.0.0/16
   Target	handson-vpc-a

4. Add another static route to direct traffic with the destination 10.2.0.0/16 to handson-vpc-b.

   

   Item	Value
   Destination	10.2.0.0/16
   Target	handson-vpc-b

5. Verify that the static routes have been configured correctly.

   

Step 3. Configure subnet route policies

1. Navigate to Beyond Networking Service > VPC > Route Tables and check the list of route tables. Access the details of the main subnet's route table for both handson-vpc-a and handson-vpc-b, and modify the routing information.

   

2. Access the route table details for the main subnet of handson-vpc-a. Click [Add Route] to add a new route.

   

3. Add a route where the destination is the CIDR of handson-vpc-b, and set handson-transit-gateway as the target.

4. Verify the added route information.

   

5. Access the route table details for the main subnet of handson-vpc-b. Click [Add Route] to add a new route.

   

6. Add a route where the destination is the CIDR of handson-vpc-a, and set handson-transit-gateway as the target.

   

7. Verify the added route information.

   

Step 4. Create instances and verify connectivity

1. Go to KakaoCloud Console > Virtual Machine > Instances and click [Add Instance] to create instances. Refer to the table below for the configurations.

   Item	Sub-item	Instance 1	Instance 2
   Basic Information	Name	handson-instance-a	handson-instance-b
   	Count	1	1
   Image		Ubuntu 20.04	Ubuntu 20.04
   Instance Type		m2a.large	m2a.large
   Volume		Root volume, 20GB, SSD	Root volume, 20GB, SSD
   Key Pair		{User Key Pair}	{User Key Pair}
   Network	VPC	handson-vpc-a	handson-vpc-b
   	Subnet	main	handson-vpc-b
   	Security Group	{Refer below}	{Refer below}

2. Configure security policies to enable communication. Refer to the table below:

   Policy	Inbound	Inbound	Outbound
   Protocol	ICMP	TCP	ALL
   Source	10.0.0.0/8	{User Public IP}/32	0.0.0.0/0
   Port Number	-	22	-
   Policy Description	ping	ssh	all

   info

   Use online tools like WhatIsMyIP.com to check your public IP address.

3. Assign a public IP to the instance and connect via SSH.

   Connect via SSH

   ssh ubuntu@{INSTANCE_PUBLIC_IP} -i {KEY_PAIR}

4. After connecting, verify communication between instances using the ping command. The image below shows the result of using ping from instance-a in vpc-a to instance-b in vpc-b.

   Ping from instance-a to instance-b

   ping {INSTANCE_PRIVATE_IP}

   

   The following image shows the result of using ping from instance-b in vpc-b to instance-a in vpc-a.