A packet processing method performed by a switching device, wherein the switching device comprises: o a table comprising a correspondence between a first flow entry and a first prefix, the first prefix being formed by a first offset together with a first size, o wherein the first flow entry comprises a first match field and a first instruction set, the first match field comprising the first prefix and first data, wherein the first offset indicates an amount of offset, which is counted from a start position of a received packet frame of a data packet and the first size indicates a size of consecutive bits following the first offset, and the first offset and the first size jointly designate a continuous bit field of the first size in the data packet, wherein the packet processing method comprises the steps of: a.) receiving the data packet, b.) acquiring in the data packet a bit field located in the data packet at the first offset as indicated by the first prefix and having the first size as indicated by the first prefix (step 61), c.) comparing the bit field with the first data (step 62), d.) if the bit field is the same as the first data, determining that the first flow entry matches the data packet, and e.) after step d.), performing a processing according to an action in the first instruction set of the first flow entry (step 64), wherein the packet processing method is characterized in that it further comprises f.) upon determining that the bit field is not the same as the first data, determining that the first flow entry does not match the data packet and encapsulating the data packet into a packet used to request a second flow entry comprising a second match field and a second instruction set, the second match field comprising a second prefix formed by a second offset together with a second size and further comprising second data, wherein furthermore the second data are to match a bit field in the data packet as indicated by the second offset and the second size, and sending the packet used to request the second flow entry to a controller of the switching device (step 65). o a table comprising a correspondence between a first flow entry and a first prefix, the first prefix being formed by a first offset together with a first size, o wherein the first flow entry comprises a first match field and a first instruction set, the first match field comprising the first prefix and first data, wherein the first offset indicates an amount of offset, which is counted from a start position of a received packet frame of a data packet and the first size indicates a size of consecutive bits following the first offset, and the first offset and the first size jointly designate a continuous bit field of the first size in the data packet, a.) receiving the data packet, b.) acquiring in the data packet a bit field located in the data packet at the first offset as indicated by the first prefix and having the first size as indicated by the first prefix (step 61), c.) comparing the bit field with the first data (step 62), d.) if the bit field is the same as the first data, determining that the first flow entry matches the data packet, and e.) after step d.), performing a processing according to an action in the first instruction set of the first flow entry (step 64), wherein the packet processing method is characterized in that it further comprises f.) upon determining that the bit field is not the same as the first data, determining that the first flow entry does not match the data packet and encapsulating the data packet into a packet used to request a second flow entry comprising a second match field and a second instruction set, the second match field comprising a second prefix formed by a second offset together with a second size and further comprising second data, wherein furthermore the second data are to match a bit field in the data packet as indicated by the second offset and the second size, and sending the packet used to request the second flow entry to a controller of the switching device (step 65).