NTHC: A nested tunnel header compression mechanism for tunneling over IP

The Internet Protocol (IP) is the widely used transport protocol for wired and wireless networks. In the Internet applications such as interactive games, messaging, etc., the payload of the IP packet is of the smaller size or the same size as compared to the header size of the packet. Moreover, the size of headers in IP packets also increases in various IP tunneling mechanisms that are used in multiple contexts such as virtual-private networks and transitions of IPv4-to-IPv6. These tunneling mechanisms add multiple levels of encapsulations in each packet. Thus, they introduce an overhead due to a high packet header size which leads to a poor performance in wireless network links. This protocol header overhead further increases when several nested tunnels are used in end-to-end path. Techniques to compress IP packet headers can be used on tunnel headers to reduce the overhead introduced by protocol headers. However, the existing techniques available for packet header compression are not suitable to the characteristics of IP tunneling. In this paper, we propose a design of a novel nested tunneling header compression (NTHC) mechanism to efficiently use IP tunneling while reducing the transmission overhead of tunneling protocol headers. NTHC reduces the protocol header overhead especially in the scenarios where several nested tunnels are in use for end-to-end connectivity. NTHC is able to compress headers of various tunneling protocols such as UDP, PPP and L2TP. Our prototype implementation of the NTHC shows it's feasibility. The evaluation results show the effectiveness and efficiency of the proposed solution.