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Routing Traffic to Backend Servers in Different VPCs from the Load Balancer

You can use ELB to route traffic to backend servers in two VPCs connected over a VPC peering connection.

Solution Design​

  • A dedicated load balancer named ELB-Test is running in VPC-Test-01 (172.18.0.0/24).
  • An ECS named ECS-Test is running in VPC-Test-02 (172.17.0.0/24).
  • IP as a Backend is enabled for the dedicated load balancer ELB-Test, and ECS-Test in VPC-Test-02 (172.17.0.0/24) is added to the backend server group associated with ELB-Test.

Figure 1 Topology

Advantages

You can enable IP as a Backend for the dedicated load balancer to route incoming traffic to servers in different VPCs from the load balancer.

Prerequisites​

Resource TypeResource NameDescriptionQuantity
VPCVPC-Test-01The VPC where ELB-Test is running: 172.18.0.0/241
VPC-Test-02The VPC where ECS-Test is running: 172.17.0.0/241
VPC peering connectionPeering-TestThe connection that connects the VPC where ELB-Test is running and the VPC where ECS-Test is running Local VPC: 172.18.0.0/24 Peer VPC: 172.17.0.0/241
Route tableRoute-VPC-Test-01The route table of VPC-Test-01 Destination: 172.17.0.0/241
Route-VPC-Test-02The route table of VPC-Test-02 Destination: 172.18.0.0/241
ELBELB-TestThe dedicated load balancer1
EIPEIP-TestThe EIP bound to ELB-Test1
ECSECS-TestThe ECS works in VPC-Test-021

Table 1 Resource planning

note

To calculate the fees you can visit Open Telekom Cloud Price calculator.

Procedure​

Figure 2 Process of associating servers in a VPC that is different from the dedicated load balancer

Creating VPCs​

  1. Log in to the management console.

  2. Under Networking, select Virtual Private Cloud. On the Virtual Private Cloud page displayed, click Create VPC.

  3. Configure the parameters as follows and click Create Now. For details on how to create a VPC, see the Virtual Private Cloud User Guide.

    • Name: VPC-Test-01
    • IPv4 CIDR Block: 172.18.0.0/24
    • Configure other parameters as required.

    Figure 3 Creating VPC-Test-01

  4. Repeat steps 2 & 3 to create the other VPC.

    • Name: VPC-Test-02
    • IPv4 CIDR Block: 172.17.0.0/24
    • Configure other parameters as required.

    Figure 4 Creating VPC-Test-02

Creating a VPC Peering Connection​

  1. In the navigation pane on the left, click VPC Peering.

  2. In the upper right corner, click Create VPC Peering Connection.

  3. Configure the parameters as follows and click OK. For details on how to create a VPC peering connection, see the Virtual Private Cloud User Guide.

    • Name: Peering-Test
    • Local VPC: VPC-Test-01
    • Peer VPC: VPC-Test-02
    • Configure other parameters as required.

    Figure 5 Creating Peering-Test

Adding Routes for the VPC Peering Connection​

  1. In the navigation pane on the left, click Route Tables.

  2. In the upper right corner, click Create Route Table.

  3. Configure the parameters as follows and click OK. For details on how to create a route table, see the Virtual Private Cloud User Guide.

    • Name: Route-VPC-Test-01
    • VPC: VPC-Test-01
    • Destination: 172.17.0.0/24
    • Next Hop Type: VPC peering connection
    • Next Hop: Peering-Test

    Figure 6 Creating Route-VPC-Test-01

  4. Repeat steps 2 & 3 to create the other route table.

    • Name: Route-VPC-Test-02
    • VPC: VPC-Test-02
    • Destination: 172.18.0.0/24
    • Next Hop Type: VPC peering connection
    • Next Hop: Peering-Test

Creating an ECS​

  1. Under Computing, click Elastic Cloud Server.

  2. In the upper right corner, click Create ECS.

  3. Select VPC-Test-02 as the VPC and set ECS Name to ECS-Test. Configure other parameters as required. For details, see Elastic Cloud Server User Guide.

    Figure 7 Creating ECS-Test

  4. Deploy Nginx on the ECS.

    Figure 8 Deploying Nginx on ECS-Test

Creating a Dedicated Load Balancer and Adding an HTTP Listener and a Backend Server Group to the Load Balancer​

  1. Under Networking, click Elastic Load Balance.

  2. In the upper right corner, click Create Elastic Load Balancer.

  3. Configure the parameters as follows. For details, see Elastic Load Balance User Guide.

    • Type: Dedicated
    • IP as a Backend: Enable
    • VPC: VPC-Test-01
    • Name: ELB-Test
    • Configure other parameters as required.

    Figure 9 Creating ELB-Test

  4. Add an HTTP listener and a backend server group to the dedicated load balancer. For details, see Elastic Load Balance User Guide.

    Figure 10 HTTP listener and backend server group

Adding the ECS to the Backend Server Group​

  1. Locate the created dedicated load balancer and click its name ELB-Test.

  2. On the Listeners tab page, locate the HTTP listener added to the dedicated load balancer and click its name.

  3. In the Backend Server Groups tab on the right, click IP as Backend Servers.

    Figure 11 IP as backend servers

  4. Click Add IP as Backend Server, configure the parameters, and click OK. For details, see Elastic Load Balance User Guide.

    • Backend Server IP Address: Private IP address of ECS-Test (172.17.0.205)
    • Backend Port: the port enabled for Nginx on ECS-Test
    • Weight: Set this parameter as required.

    Figure 12 Adding ECS-Test using its IP address

Verifying Traffic Routing​

note

EIP is not necessary as long as you don't want to access the ELB externally, you can always access the ELB from its private IP.

  1. Locate the dedicated load balancer ELB-Test and click More in the Operation column.

  2. Select Bind IPv4 EIP to bind an EIP to ELB-Test.

    Figure 13 EIP bound to the load balancer

  3. Enter http://<EIP> in the address box of your browser to access the dedicated load balancer. If the following page is displayed, the load balancer routes the request to ECS-Test, which processes the request and returns the requested page.

    note

    In case of unhealthy connection of the backend server group, check if the ECS subnet and ELB subnet are associated with the above created route tables.

    Figure 14 Verifying that the request is routed to ECS-Test