Abstract: Compared with traditional networking technologies, SDN technologies separate the control plane of the networking from the data plane, making the networking programmable. Most of the SDN switches, like OpenFlow, POF, P4, are implemented based on the match-action table model. Different from protocol-aware SDNs, such as OpenFlow, protocol-oblivious SDNs define protocol fields by {offset, length} structures, so as to realize the parsing and processing of any protocol fields. However, packets to be processed may have packet headers with different lengths. In order to match the fields in packet header protocols, the control plane needs to install more flow tables to parse packets, which results in complex flow tables and pipelines. To address the above problems, this paper proposes a flow table merging scheme on programmable data planes based on the MAT model, which extends the action set in the MAT model. The starting offset of packets can be adjusted dynamically with specific actions when a packet queries the flow table, making the offset of the same matching fields in different packets consistently, so that flow tables with the same matching fields are merged. The scheme reduces the flow table memory consumption by about 69% at the cost of executing one more action when jumping the flow table in the POF Switch experimental scenario compatible with VLAN and QinQ.

Key words: SDN, programmable data plane, flow table merging