AS-PATH, which is composed of a series of compliance operations, is recognized as one of the mandatory attributes. AS-PATH indicates that when the routing information passes the ordered set of as in the autonomous system, the routing information needs to adopt the as-sequence mode; when the BGP publisher publishes the routing information to the iBGP counterpart, the as of the routing information_ The path property is not modified. When BGP publishers publish routes to ebgp peers, the local system should take its own as number as the last element of the sequence. AS-PATH can be used as a standard to measure computer network routing, and it is better to route as path through less autonomous system. At the same time, when receiving the routing information, the network equipment finds that the AS-PATH list contains the autonomous system number, which indicates that the routing information has been sent from the autonomous system, then it will not receive the routing information; therefore, it has become an effective means to avoid the loop problem.