A bit-forwarding ingress router, BFIR, wherein the BFIR is in a bit indexed explicit replication BIER-based network, and the router comprises: a first obtaining unit , configured to obtain a first operation, administration and maintenance, OAM, request packet according to an identifier, ID, of at least one bit-forwarding egress router, BFER, wherein the first OAM request packet comprises an ID of the BFIR, a set identifier, and a bit string corresponding to the at least one BFER, the set identifier is corresponding to the at least one BFER, and the first OAM request packet is used for testing a link between the BFIR and the at least one BFER; and a first sending unit , configured to send the first OAM request packet to the at least one BFER based on the bit string corresponding to the at least one BFER; wherein: the first obtaining unit is specifically configured to obtain the ID of the at least one BFER based on a correspondence comprising the ID of the at least one BFER and an IP address of the at least one BFER; the first obtaining unit is specifically configured to calculate the set identifier and the bit string according to the ID of the at least one BFER; the first obtaining unit is specifically configured to obtain a second OAM request packet according to the bit string, wherein a packet header of the second OAM request packet comprises the bit string and the ID of the BFIR, and a payload of the second OAM request packet comprises an OAM packet; and the first obtaining unit is specifically configured to obtain the first OAM request packet by inserting a first bit indexed explicit replication multiprotocol label switching label, BIER-MPLS label, into the second OAM request packet according to the set identifier, wherein the first BIER-MPLS label comprises a label corresponding to the set identifier. a first obtaining unit , configured to obtain a first operation, administration and maintenance, OAM, request packet according to an identifier, ID, of at least one bit-forwarding egress router, BFER, wherein the first OAM request packet comprises an ID of the BFIR, a set identifier, and a bit string corresponding to the at least one BFER, the set identifier is corresponding to the at least one BFER, and the first OAM request packet is used for testing a link between the BFIR and the at least one BFER; and a first sending unit , configured to send the first OAM request packet to the at least one BFER based on the bit string corresponding to the at least one BFER; wherein: the first obtaining unit is specifically configured to obtain the ID of the at least one BFER based on a correspondence comprising the ID of the at least one BFER and an IP address of the at least one BFER; the first obtaining unit is specifically configured to calculate the set identifier and the bit string according to the ID of the at least one BFER; the first obtaining unit is specifically configured to obtain a second OAM request packet according to the bit string, wherein a packet header of the second OAM request packet comprises the bit string and the ID of the BFIR, and a payload of the second OAM request packet comprises an OAM packet; and the first obtaining unit is specifically configured to obtain the first OAM request packet by inserting a first bit indexed explicit replication multiprotocol label switching label, BIER-MPLS label, into the second OAM request packet according to the set identifier, wherein the first BIER-MPLS label comprises a label corresponding to the set identifier. <EOS>