ROUTING ADVERTISEMENT METHOD, PATH ESTABLISHMENT METHOD, SERVICE DATA TRANSMISSION METHOD AND AUTONOMOUS SYSTEM BORDER ROUTER

Provided in the present disclosure is a path establishment method, which is applied to a second autonomous system border router (ASBR) in a second autonomous domain. The method comprises: receiving cross-domain routing, wherein the cross-domain routing is cross-domain routing that is advertised by a first ASBR in a first autonomous domain; according to an autonomous system number, a node identifier and a flexible algorithm identifier that are carried in the cross-domain routing, selecting a cross-domain link that meets a predetermined condition from among cross-domain links between a second ASBR and the first ASBR; and according to the cross-domain link that meets the predetermined condition, performing, in a second autonomous domain, intra-domain advertisement on a prefix of the cross-domain routing, a flexible algorithm identifier corresponding to the prefix and an accumulated metric value of the prefix, and generating cross-domain routing based on an intra-domain routing protocol in the second autonomous d