Adding an AS_Path Filter to an AS_Path List
Scenarios
This section describes how to add an AS_Path filter to an AS_Path list. Each AS_Path list can have multiple AS_Path filters.
Notes and Constraints
- AS_Path filters change the path through which network traffic passes. If a route policy has already been associated with an enterprise router, evaluate the impact on services before adding an AS_Path filter to an AS_Path list.
- Each filter in an AS_Path list must have its unique sequence number.
Prerequisites
An AS_Path list is available. You can create one by referring to Creating an AS_Path List.
Procedure
- Log in to the management console.
- Click
in the upper left corner and select the desired region and project.
- Click Service List and choose Networking > Enterprise Router.
The Enterprise Router page is displayed.
- In the navigation pane on the left, choose Routing Control > AS_Path Lists.
The AS_Path Lists page is displayed.
- Click the name of the target AS_Path list.
The AS_Path filters are displayed.
- Click Add AS_Path Filter in the upper left corner of the filter list.
The Add AS_Path Filter dialog box is displayed.
- Configure the parameters based on Table 1.
Table 1 Parameters for adding an AS_Path filter Parameter
Description
Example Value
Sequence Number
Mandatory
An AS_Path list consists of one or more AS_Path filters that are applied to filter routes based on their sequence numbers, in ascending order. A sequence number can be from 0 to 65535.
10
Action
Mandatory
Select Allow or Deny.
- If a route matches an AS_Path filter with Action set to Allow, the route is allowed.
- If the AS_Path filter has Action set to Deny, the route is denied.
Allow
Regular Expression
A regular expression is a string that describes a characteristic and verifies whether another string conforms to this characteristic. An AS_Path filter defines an AS_Path regular expression to match AS_Path attributes of BGP routes for filtering BGP routes.
For details, see AS_Path Regular Expressions.
65+
- Click OK.
In the AS_Path filter list, you can view the created AS_Path filter.
Follow-Up Operations
Deleting an AS_Path Filter from an AS_Path List: An AS_Path filter cannot be modified after being added. You can delete an AS_Path filter that you do not need and add another one.
- Scenarios
- Notes and Constraints
- Prerequisites
- Procedure
- Follow-Up Operations