TCP performance enhancement over mobile IPv6: innovative fragmentation avoidance and adaptive routing techniques

Mobile Internet Protocol version 6 (MIPv6) is a proposal for handling the routing of IPv6 packets to mobile nodes in a foreign network. There are two methods for routing IPv6 packets from the correspondent node (CN) to the mobile node (MN): triangular routing (TR) and route optimisation (RO). With MIPv6 route optimisation, the CN uses the care-of address (CoA) as the destination address to transfer packets to the MN. Hence the MIPv6 module of the CN adds the mobility routing header (MRH) to store the home address of the MN. This increases packet sizes and may result in fragmentation. Fragmentation degrades TCP performance over MIPv6. The cost of fragmentation is discussed and innovative fragmentation avoidance techniques are proposed. The cost of fragmentation is studied by carrying out experiments in a real IPv6 backbone (6Bone), where it is found that improved performance can be obtained by implementing innovative fragmentation avoidance techniques in the TCP/MIPv6 protocol stack of the Kame software. The efficiency of fragmentation avoidance techniques is also calculated. The impact of MIPv6 with triangular routing on the TCP performance is also illustrated. A performance comparison between MIPv6 with route optimisation and triangular routing is discussed. Based on this performance comparison, a generic adaptive routing technique is proposed.