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Transit Router

Route policy

Creating a route policy

Scenarios

Route policies provide capabilities for the Transit Router (TR), such as filtering routes based on their direction (inbound/outbound), and influencing path selection by modifying route attributes. By configuring route policies for a TR, you can flexibly control the route propagation scope and path selection outcomes. The route prefix in route policies supports referencing VPC prefix lists to simplify configuration.

Instructions

You must add at least one entry to a single route policy.

You can add up to 10 entries to a single route policy in a single action.

Procedure

Click the name of the target TR instance.

In the section below Basic information, select the Route policy tab.

Click Create route policy and configure the route policy based on the table below.

Parameter name	Description	Example
Basic information
Name	Type the name for the route policy.	policy01
Policy direction	Select the direction that the route policy takes effect on. Inbound: The direction that the TR learns routes from the network instance. Affects routes learned by TR from the network instance. Outbound: The direction that the TR publishes routes to the network instance. Affects routes published by the TR to the network instance.	Inbound
Policy entry
Priority	Type an integer between 1 and 10,000 as the priority for the policy entry. A lower priority value indicates higher precedence. When the target route matches a route policy, policy entries are matched in order of priority. tip For an inbound route policy, the target route refers to all route entries whose route type is Route learning in the TR route table attached to this route policy. For an outbound route policy, the target route refers to all route entries in the TR route table associated with this route policy. Within a single route policy, the priority for each entry must be unique.	1
Match conditions	Configure match conditions for the policy entry. Each policy entry must contain at least one match condition. Match condition types: Route prefix: Select the route prefix type and match mode in order. Select the match mode and type the IPv4 or IPv6 CIDR block, and then confirm by entering a semicolon or pressing Enter. IPv4/IPv6 CIDR: Type the IPv4 or IPv6 CIDR block, and then confirm by entering a semicolon or pressing Enter. Exact match: The match is successful only when the route's destination CIDR block exactly matches this CIDR block. Otherwise, the match fails. Fuzzy match: The match is successful when the route's destination CIDR block is identical or contained within this CIDR block. Otherwise, the match fails. tip The IPv6 feature of TR is in the beta stage. To type an IPv6 CIDR block, please contact your account manager. You can add a maximum of 200 unique route prefixes to a single policy entry in a single request. Separate multiple route prefixes with either the English semicolons (;) or Chinese semicolons (；). Prefix list: Exact match: The match succeeds if the destination CIDR block of the route is identical to any CIDR in this prefix list. Otherwise, it fails. Fuzzy match: The match succeeds if the destination CIDR block of the route is identical to or contained within any CIDR in this prefix list. Otherwise, it fails. Source instance type/Source instance ID: Match all routes learned by the TR from the specified instance type or the specified network instance. Supported network instance types include VPC, DC Gateway, inter-region TR, VPN. Destination instance type/Destination instance ID: Match all routes published by the TR to the specified instance type or the specified network instance. Supported network instance types include VPC, DC Gateway, inter-region TR, VPN. tip Static or Blackhole route entries in a TR route table lack a source instance by default. Consequently, these routes cannot match any outbound policy that includes a Source instance type match condition. When the policy direction is set to Inbound, you cannot configure Destination instance type or Destination instance ID match conditions. A single policy entry can include multiple different types of match conditions. A single condition type can contain multiple values. Within a single route policy entry, different match conditions are combined with a logical "AND", while multiple values for the same condition are combined with a logical "OR". For detailed matching mechanism and examples, see Route Policy Matching rules.	Route prefix (exact match) 192.168.1.0/24
Policy action	The action performed on the target route upon a successful route policy match. Permit: Allow the routes that match the route policy to pass. Deny: Reject the routes that match the route policy from passing. When the policy action is set to Permit, specify whether to enable the Set route attributes option. If the option is enabled, select one of the following methods to modify the target route's AsPath: Append As Path: Append the specified AsPath to the AsPath of the target route. Press Enter to confirm after specifying AsPath. Replace As Path: Replace the target route's AsPath with the specified AsPath. Press Enter to confirm after specifying AsPath. tip If a route with no AsPath matches a TR route policy whose Set route attributes option is enabled, appending AsPath and replacing AsPath are functionally equivalent. Either will result in the target route gaining the AsPath you specify.	Permit

Click Create to complete the action.