Route notification method, path establishment method and service data transmission method

The embodiment of the invention provides a path establishment method, which is used for a second ASBR in a second autonomous domain, and comprises the following steps: receiving a cross-domain route, the cross-domain route being a cross-domain route announced by a first ASBR in a first autonomous domain; according to an AS number, a node identifier and a flexible algorithm identifier carried in the cross-domain route, selecting a cross-domain link meeting a predetermined condition from cross-domain links between the second ASBR and the first ASBR; and according to the cross-domain link meeting the predetermined condition, performing intra-domain notification on the prefix of the cross-domain route, the flexible algorithm identifier corresponding to the prefix and the accumulated metric value of the prefix in the second autonomous domain, and generating the cross-domain route based on the intra-domain routing protocol in the second autonomous domain. The embodiment of the invention further provides a route not