Packet Tagging System Using Adaptive MSS Clamping on TCP

In recent years, along with the spread of virtual networks that can be flexibly controlled and expanded at the software level, the network operations beyond the existing IP communication framework have been widely examined. As a result of such efforts, information (tag) for the management of the new network operation must be added to the existing network flow. Therefore, to solve these problems, an encapsulation technology was used with the existing tagging technology, such as VLAN and MPLS, for sharing additional information. However, for this method, the network parameters, such as MTU, must be reconfigured, and as the maximum length of the tag is fixed, embedding information of an arbitrary length is impossible. Therefore, we propose a packet tagging system, which can add arbitrary length data to TCP segments by newly creating an adaptive TCP maximum-segment-size (MSS) clamping to tag network flows. The packet tagging system dynamically changes the MSS in one connection communication unit in the TCP so that the TCP segment size does not exceed the MTU size by adding information of an arbitrary length. In other words, this system features the ability of two communication hosts to add information of an arbitrary length without the need to change network parameters (MTU size and constitutional change to application). We implemented the packet tagging system and verified its influence on the communication throughput and the system performance by the change of the additional-information size in the experiment. As a result, the proposed system was confirmed to achieve sufficient throughput and showed high practicality.