A bit forwarding ingress router, BFIR, wherein the BFIR is located in a bit index based explicit replication, BIER, network, and the BFIR 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 the ID of the BFIR, a bit string, and a set identifier to which the bit string belongs; and the bit string corresponds to the at least one BFER; wherein: the first obtaining unit is configured to obtain an IP address of the at least one BFER from a multicast flow overlay and to obtain the ID of the at least one BFER based on a correspondence comprising the ID of the at least one BFER and the IP address of the at least one BFER; the first obtaining unit is 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 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 packet comprises an OAM packet; and the first obtaining unit is 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; and; a first sending unit, configured to send the first OAM request packet to the at least one BFER. 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 the ID of the BFIR, a bit string, and a set identifier to which the bit string belongs; and the bit string corresponds to the at least one BFER; wherein: the first obtaining unit is configured to obtain an IP address of the at least one BFER from a multicast flow overlay and to obtain the ID of the at least one BFER based on a correspondence comprising the ID of the at least one BFER and the IP address of the at least one BFER; the first obtaining unit is 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 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 packet comprises an OAM packet; and the first obtaining unit is 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; and; a first sending unit, configured to send the first OAM request packet to the at least one BFER. the first obtaining unit is configured to obtain an IP address of the at least one BFER from a multicast flow overlay and to obtain the ID of the at least one BFER based on a correspondence comprising the ID of the at least one BFER and the IP address of the at least one BFER; the first obtaining unit is 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 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 packet comprises an OAM packet; and the first obtaining unit is 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; and; a first sending unit, configured to send the first OAM request packet to the at least one BFER.