You can create a custom route table in a virtual private cloud (VPC) and add subnet routes to the custom route table. Then, you can associate the custom route table with a vSwitch to control the traffic of the vSwitch. This facilitates network management.

Prerequisites

A VPC is created. For more information, see Create a VPC.

Background information

Before you add subnet routes to a custom route table, take note of the following limits:

  • Each VPC can contain at most 10 route tables including the system route table.
  • Each vSwitch can be associated with only one system route table or one custom route table.
  • Custom route tables do not support active/standby routes or load-balancing routes.

Step 1: Create a custom route table

  1. Log on to the VPC console.
  2. In the left-side navigation pane, click Route Tables.
  3. Select the region where you want to create a custom route table.
    For more information about regions that support custom route tables, see Regions that support custom route tables.
  4. On the Route Tables page, click Create Route Table.
  5. In the Create Route Table dialog box, set the following parameters and click OK.
    Parameter Description
    Resource Group Select the resource group to which the route table belongs.
    VPC Select the VPC to which the route table belongs.

    If a VPC contains an Elastic Compute Service (ECS) instance that belongs to one of the following instance families, you cannot create a custom route table for the VPC.

    ecs.c1, ecs.c2, ecs.c4, ecs.ce4, ecs.cm4, ecs.d1, ecs.e3, ecs.e4, ecs.ga1, ecs.gn4, ecs.gn5, ecs.i1, ecs.m1, ecs.m2, ecs.mn4, ecs.n1, ecs.n2, ecs.n4, ecs.s1, ecs.s2, ecs.s3, ecs.se1, ecs.sn1, ecs.sn2, ecs.t1, and ecs.xn4.

    To create a custom route table, you must upgrade or release ECS instances that do not support advanced VPC features.
    Note If your VPC contains ECS instances of the preceding instance families and a custom route table is created, you must upgrade or release the instance. Otherwise, the custom route table cannot work as expected. For more information, see Advanced VPC features.
    Name Enter a name for the route table.

    The name must be 2 to 128 characters in length, and can contain digits, underscores (_), and hyphens (-). It must start with a letter.

    Description Enter a description for the route table.

    The description must be 2 to 256 characters in length and cannot start with http:// or https://.

    After you create custom route tables, you can go to the Route Tables page to view route tables whose Route Table Type is Custom.The following system route entries are automatically added to custom route tables:
    • A route destined for the CIDR block 100.64.0.0/10. This route is used for communication between cloud resources within the VPC.
    • A route destined for the CIDR block of a vSwitch of the VPC to which the route table belongs. This route is used for communication between cloud resources within the vSwitch.
    For example, you have created two vSwitches whose CIDR blocks are 192.168.1.0/24 and 192.168.0.0/24. These vSwitches are deployed in the VPC whose CIDR block is 192.168.0.0/16. Custom route tables that you create for the VPC include the following route entries:
    Destination CIDR block Next hop Type
    100.64.0.0/10 - System route
    192.168.1.0/24 - System route
    192.168.0.0/24 - System route

Step 2: Add subnet routes

  1. Log on to the VPC console.
  2. In the left-side navigation pane, click Route Tables.
  3. In the top navigation bar, select the region to which the route table belongs.
  4. On the Route Tables page, find the route table that you want to manage and click the ID of the route table.
  5. In the Route Table Details section, choose Route Entry List > Custom and click Add Route Entry.
  6. In the Add Route Entry panel, set the following parameters and click OK.
    Parameter Description
    Name Enter a name for the route entry.

    The name must be 2 to 128 characters in length and can contain letters, digits, underscores (_), and hyphens (-). The name must start with a letter.

    Destination CIDR block The CIDR block to which you want to forward traffic.
    Next Hop Type Select the type of next hop. Valid values:
    • ECS Instance: Traffic destined for the specified CIDR block is routed to the specified ECS instance.

      Select this type if you want to route traffic to an ECS instance for centralized traffic forwarding and management. For example, when an ECS instance is configured as the public-facing gateway to manage the traffic from other ECS instances to the Internet.

    • HaVip Address: Traffic destined for the specified CIDR block is routed to the specified high-availability virtual IP address (HAVIP).
    • VPN Gateway: Traffic destined for the specified CIDR block is routed to the specified VPN gateway.
    • NAT Gateway: Traffic destined for the specified CIDR block is routed to the specified NAT gateway.
    • Secondary ENI: Traffic destined for the specified CIDR block is routed to the specified secondary elastic network interface (ENI).
    Resource Group Select the resource group to which the next hop belongs.

    This parameter is required only when you set Next Hop Type to ECS Instance or Secondary ENI.

    ECS Instance/HaVip Address/VPN Gateway/NAT Gateway/Secondary Network Interface Select an instance as the next hop.

Step 3: Associate the custom route table with a vSwitch

You can associate the custom route table with a vSwitch to manage the routes of the vSwitch. Each vSwitch can be associated with only one system route table or one custom route table. Perform the following operations to associate the custom route table with a vSwitch.

  1. Log on to the VPC console.
  2. In the left-side navigation pane, click Route Tables.
  3. In the top navigation bar, select the region to which the route table belongs.
    For more information about the regions that support custom route tables, see Regions that support custom route tables.
  4. On the Route Tables page, find the route table and click its ID.
  5. In the Route Table Details section, click the Associated vSwitch tab and click Associate vSwitch.
  6. On the Associate vSwitch page, select the vSwitch that you want to associate and click OK.