Method for communication in an IP network, comprising the following steps implemented by a client device (T, T1, T2, T3) which is able to implement a single TCP, Transmission Control Protocol, connection and a multipath TCP connection: - a step (E1) of discovering at least one test server (CHECK_SERVER) which is able to implement a multipath TCP connection, - a step (E2) of attempting to establish at least one multipath TCP connection with the test server (CHECK_SERVER) along at least one path which makes it possible to reach said client device (T, T1, T2, T3), said step comprising a determination by exchanging test data with the test server (CHECK_SERVER) : if multipath TCP options sent by the client device (T, T1, T2, T3) or by the test server (CHECK_SERVER) are filtered or modified by a service function placed in cut-through configuration of flows on said path, or if they are received correctly by the test server (CHECK_SERVER) or by the client device (T, T1, T2, T3) , - a step (E3) of recording a status (PATH_CHECKED) of said path with regard to its compatibility with multipath TCP connections, said status being determined depending on a result of said determination by the client device, said status indicating a compatibility of said path with multipath TCP connections if it is determined during said determination that the multipath TCP options are received correctly, and an incompatibility with multipath TCP connections otherwise; the method being characterized in that it further comprises: - if none of the paths which make it possible to reach said client device (T, T1, T2, T3) is compatible with multipath TCP connections, a step during which said client device (T, T1, T2, T3) uses the single TCP transport mode to establish a connection with another client device, or connect to another client device, following the reception of a message establishing a multipath connection and sent by this other client device. - a step (E1) of discovering at least one test server (CHECK_SERVER) which is able to implement a multipath TCP connection, - a step (E2) of attempting to establish at least one multipath TCP connection with the test server (CHECK_SERVER) along at least one path which makes it possible to reach said client device (T, T1, T2, T3), said step comprising a determination by exchanging test data with the test server (CHECK_SERVER) : if multipath TCP options sent by the client device (T, T1, T2, T3) or by the test server (CHECK_SERVER) are filtered or modified by a service function placed in cut-through configuration of flows on said path, or if they are received correctly by the test server (CHECK_SERVER) or by the client device (T, T1, T2, T3) , if multipath TCP options sent by the client device (T, T1, T2, T3) or by the test server (CHECK_SERVER) are filtered or modified by a service function placed in cut-through configuration of flows on said path, or if they are received correctly by the test server (CHECK_SERVER) or by the client device (T, T1, T2, T3) , - a step (E3) of recording a status (PATH_CHECKED) of said path with regard to its compatibility with multipath TCP connections, said status being determined depending on a result of said determination by the client device, said status indicating a compatibility of said path with multipath TCP connections if it is determined during said determination that the multipath TCP options are received correctly, and an incompatibility with multipath TCP connections otherwise; - if none of the paths which make it possible to reach said client device (T, T1, T2, T3) is compatible with multipath TCP connections, a step during which said client device (T, T1, T2, T3) uses the single TCP transport mode to establish a connection with another client device, or connect to another client device, following the reception of a message establishing a multipath connection and sent by this other client device. <EOS>