Preventing Private AS Numbers from Propagating to BGP

An ISP can assign private AS numbers (64512 to 65535) to a customer to conserve globally unique AS numbers. When an ISP does this, a BGP update from a customer network to the ISP has the private AS number in its "AS_PATH" attribute. When the ISP propagates its network information to other ISPs, the private AS number is usually included. To avoid this, you can configure Gaia Embedded to remove the private AS number from BGP update messages to external peers.

To configure Gaia Embedded to remove private AS numbers from BGP updates, enable the Remove Private AS option on the configuration page for an external peer.

If you enable this option, private AS numbers are removed from BGP updates based on these rules:

• If the "AS_PATH" includes both public and private AS numbers, the private AS numbers are not removed.

• If the "AS_PATH" contains the AS number of the destination peer, private AS numbers are not removed.

• If the "AS_PATH" includes confederations and all the AS numbers in the "AS_PATH" are private, all the private AS numbers are removed.