A route selection method, for routing a user access request sent by a user to a source site via a network of acceleration nodes connecting the user to the source site; the network of acceleration nodes comprising an ingress acceleration node, egress acceleration nodes wherein each egress network acceleration node denotes a last-hop network acceleration node connected to the source site ; the ingress network acceleration node is connected to each of the egress network acceleration nodes directly or through one or more intermediary network acceleration nodes; the acceleration nodes denoting proxy service equipments configured at different geographic locations and in networks provided by different carriers, the method comprising: when the ingress network acceleration node receives the user access request: detecting, by the ingress network acceleration node, a link delay from the ingress network acceleration node to each next-hop network acceleration node, and determining, by the ingress network acceleration node, whether the each next-hop network acceleration node is available based on the detected link delay; wherein for each thus determined as available next-hop network acceleration node, sending by the ingress network acceleration node a detection request to each available next-hop network acceleration node wherein the each available next-hop network acceleration node is adapted to continue to detect and to determine availability based on link delay of next-hop network acceleration node until each egress network acceleration node is reached, thus the delay from the ingress network acceleration node to each egress network acceleration node is the sum of the delays of each intermediate link; sending, by the ingress network acceleration node, a detection request regarding the source site Internet Protocol, IP, address to each reached egress network acceleration node to obtain a link delay from the each reached egress network acceleration node to the source site IP address; and selecting, by the ingress network acceleration node, a desired route of the user access request to reach the source site IP address, based on a link delay from the ingress network acceleration node to the each reached egress network acceleration node and a link delay from the each reached egress network acceleration node to the source site IP address. detecting, by the ingress network acceleration node, a link delay from the ingress network acceleration node to each next-hop network acceleration node, and determining, by the ingress network acceleration node, whether the each next-hop network acceleration node is available based on the detected link delay; wherein for each thus determined as available next-hop network acceleration node, sending by the ingress network acceleration node a detection request to each available next-hop network acceleration node wherein the each available next-hop network acceleration node is adapted to continue to detect and to determine availability based on link delay of next-hop network acceleration node until each egress network acceleration node is reached, thus the delay from the ingress network acceleration node to each egress network acceleration node is the sum of the delays of each intermediate link; sending, by the ingress network acceleration node, a detection request regarding the source site Internet Protocol, IP, address to each reached egress network acceleration node to obtain a link delay from the each reached egress network acceleration node to the source site IP address; and selecting, by the ingress network acceleration node, a desired route of the user access request to reach the source site IP address, based on a link delay from the ingress network acceleration node to the each reached egress network acceleration node and a link delay from the each reached egress network acceleration node to the source site IP address. <EOS>