You can create IP prefix lists which contain single or multiple IP addresses. You use IP prefix lists to assign BGP neighbors with access permissions for route advertisement.
The IP prefix lists are referenced through BGP neighbor filters to limit the number of BGP updates that are exchanged between BGP peers. By using route filtering, you can reduce the amount of system resources needed for BGP updates.
For example, you can add the IP address 192.168.100.3/27 to the IP prefix list and deny the route from being redistributed to the edge gateway.
You can also append an IP address with less than or equal to (le) and greater than or equal to (ge) modifiers to grant or limit route redistribution. For example, 192.168.100.3/27 ge 26 le 32 modifiers match subnet masks greater than or equal to 26-bits and less than or equal to 32-bits in length.
- From the top navigation bar, select Resources and click Cloud Resources.
- In the left panel, click Edge Gateways, and click the name of the target edge gateway.
- Under Routing, click BGP and IP Prefix Lists.
- To add an IP prefix list, click New.
- Enter a name and, optionally, a description for the prefix list.
- Click New and add a CIDR notation for the prefix.
- From the drop-down menu, select an action to apply to the prefix.
- (Optional) Enter greater than or equal to and less than or equal to modifiers to grant or limit route redistribution.
What to do next
- You can edit or delete the IP prefix list as needed.
- Configure route filtering. See Add a BGP Neighbor.