This topic describes how to work with route tables. A route table consists of route entries. Each route entry specifies the destination to which network traffic is routed. In addition to the system route table, you can create a custom route table to manage network traffic

Operations

View a route table associated with a vSwitch

You can view information about a route table that is associated with a vSwitch in the VPC console.

  1. Log on to the VPC console.
  2. In the left-side navigation pane, click vSwitch.
  3. Select the region where the vSwitch is deployed.
  4. On the vSwitch page, find the vSwitch that you want to manage and click its ID.
  5. In the vSwitch Basic Information section, click the Route tab. In the Associated with Route Table section, you can view the ID and type of the associated route table.
    • System: The vSwitch is associated with a system route table. Click Bind next to the system route table. In the Associate RouteTable dialog box, select the custom route table that you want to associate with the vSwitch.
    • Custom: The vSwitch is associated with a custom route table. To replace the custom route table, click Replace Associated Route Table and select another custom route table in the Associate RouteTable dialog box.

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 the regions that support custom route tables, see Route tables overview.
  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 the 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.c5, 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 ECS instances. 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 (-). The name 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 the custom route table is created, you can go to the Route Tables page to view the route table. Custom is displayed in the Route Table Type column of the route table. Custom route tablesThe following system route entries are automatically added to the custom route table:
    • A route entry destined for the CIDR block 100.64.0.0/10. This route entry is used for communication between cloud resources within the VPC.
    • A route entry 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, the CIDR block of your VPC is 192.168.0.0/16 and you have created two vSwitches whose CIDR block are 192.168.1.0/24 and 192.168.0.0/24 in the VPC. The custom route table that you have created for your VPC includes the following system route entries. The "-" sign in the following table indicates that the item is not applicable.
    Destination CIDR block Next hop Route entry type
    100.64.0.0/10 - System route
    192.168.1.0/24 - System route
    192.168.0.0/24 - System route

Modify basic information about a route table

  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 its ID.
  5. In the Route Table Details section, click Edit next to Name to modify the name of the route table.
    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.
  6. Click Edit next to Description to modify the description of the route table.
    The description must be 2 to 256 characters in length, and cannot start with http:// or https://.

Add and delete route entries

Before you add or delete route entries, take note of the following limits:
  • After you create a VPC, the system creates a system route table for the VPC and adds system route entries to the route table. The system route entries are used to route traffic within the VPC. You cannot create or delete system route entries. However, you can create custom route entries to route traffic from source CIDR blocks to specific destinations.
  • You can add custom route entries to both system and custom route tables.
  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 its ID.
  5. In the Route Table Details section, click the Route Entry List tab. On the tab, you can perform the following operations:
    • Add a custom route entry
      Click the Custom tab and then click Add Route Entry. 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 digits, underscores (_), and hyphens (-). The name must start with a letter.

      Destination CIDR Block Enter the CIDR block to which you want to forward traffic.
      Note If the selected route table is a system route table and the region to which the route table belongs supports IPv6, you can set Destination CIDR Block to IPv6 CIDR Block or IPv4 CIDR Block. For more information about the regions that support IPv6, see Regions that support VPC features.
      Next Hop Type Select the next hop type. 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, you can configure an ECS instance as the Internet gateway to route traffic from other ECS instances to the Internet.

      • HaVip Address: Traffic destined for the specified CIDR block is routed to the high-availability virtual IP address (HAVIP) that you select.
      • 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 ENI.
      • Forwarding Router: Traffic destined for the specified CIDR block is routed to the specified transit router.
      • IPv6 Gateway: Traffic destined for the specified CIDR block is routed to the specified IPv6 gateway.
        Note If the selected route table is a system route table, the region to which the route table belongs supports IPv6, and Destination CIDR Block is set to IPv6 CIDR Block, you can set Next Hop Type to IPv6 Gateway, ECS Instance, or Secondary 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/VPN Gateway/NAT Gateway/Secondary ENI/Forwarding Router/IPv6 Gateway Select an instance as the next hop.
    • Delete a custom route entry
      1. Find the custom route entry that you want to delete and click Delete in the Actions column.
      2. In the Delete Route Entry message, click OK.

Associate a route table with a vSwitch

You can create a custom route table in a VPC and associate the route table with a vSwitch. This way, you can manage the routes of the vSwitch, which are called subnet routes. Subnet routes help you manage network traffic with more flexibility.

You can associate a route table with multiple vSwitches. Each vSwitch can be associated with only one system route table or one custom route table. After a custom route table is associated with a vSwitch, the system route table is automatically disassociated from the 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.
  4. On the Route Tables page, find the custom route table that you want to manage and click its ID.
  5. In the Route Table Details section, click the Associated vSwitch tab and click Associate vSwitch.
  6. In the Associate vSwitch dialog box, select the vSwitch that you want to associate and click OK.

Disassociate a route table from a vSwitch

You can disassociate a custom route table from a vSwitch. After a custom route table is disassociated from a vSwitch, the vSwitch is automatically associated with the system route table.

  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 custom route table that you want to manage and click its ID.
  5. In the Route Table Details section, click the Associated vSwitch tab. Find the vSwitch that you want to manage and click Unbind in the Actions column.
  6. In the Unbind Route Table message, click OK.
    After a custom route table is disassociated from a vSwitch, the vSwitch is automatically associated with the system route table.

Delete a custom route table

You can delete custom route tables. However, you cannot delete system route tables. If the custom route table that you want to delete is associated with a vSwitch, you must first disassociate the custom route table from the 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.
  4. On the Route Tables page, find the route table that you want to delete and click Delete in the Actions column.
  5. In the Delete Route Table message, click OK.