Creating an IP Prefix List

Scenarios

This section describes how to create an IP prefix list.

Notes and Constraints

• An IP prefix list must have at least one prefix rule.
• Each prefix rule in an IP prefix list must have its unique sequence number and IP prefix.

Procedure

1. Go to the Prefix Lists page.
2. Click Create Prefix List in the upper right corner of the page.

   The Create Prefix List dialog box is displayed.

3. Configure the parameters based on Table 1.

   Table 1 Parameters for creating an IP prefix list

   Parameter	Description	Example Value
   Name	Mandatory Enter a name for the IP prefix list. The name: Can contain 1 to 64 characters. Can contain letters, digits, underscores (_), hyphens (-), and periods (.).	prefixFilter-ab
   Description	Optional Enter the description of the IP prefix list in the text box.	-
   Configuration	Mandatory Choose Quick or Advanced. Quick Enter the IP prefix in the CIDR format. An IP prefix specifies the first bits of an IP address range that a route destination must match. The following are parameters that you do not need to configure: Sequence Number: Automatically generated. The sequence number increases by a multiple of 10, with that of the first rule set to 10. The subsequent numbers are 20, 30, and so on. Action: Allow by default Min. Netmask Length and Max. Netmask Length Advanced Sequence Number: An IP prefix list consists of one or more prefix rules that are applied to filter routes based on their sequence numbers, in ascending order. A sequence number can be from 0 to 65535. You are advised to set the sequence number of the first rule to 20. Action: Select Allow or Deny. If a route matches a prefix rule with Action set to Allow, the route is allowed. If the prefix rule has Action set to Deny, the route is denied. IP Prefix: Enter the IP prefix in the CIDR format. This parameter specifies the first bits of an IP address range that a route destination must match. Min. Netmask Length: It cannot be smaller than the netmask length of the IP prefix. For example, if the netmask length of the IP prefix is 16, the min. netmask length must be greater than or equal to 16 (for example, 18). Max. Netmask Length: It cannot be smaller than the min. netmask length. For example, if the min. netmask length is 18, the max. netmask length must be from 18 to 32 (for example, 20).	Sequence Number: 10 Action: Allow IP Prefix: 10.0.0.0/16 Min. Netmask Length: 20 Max. Netmask Length: 28

4. Click OK.

   You can view the created IP prefix list.

Follow-Up Operations

Creating a Route Policy: An IP prefix list takes effect through a route policy.