Enhanced TCP performance 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 of IPv6 packets from the correspondent node (CN) to the mobile node (MN): triangular routing (TR) and route optimisation (RO). With MIPv6 RO, 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 transmission control protocol (TCP) performance over MIPv6. The paper discusses the cost of fragmentation and innovative fragmentation avoidance techniques. 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 paper also illustrates the impact of MIPv6 TR on TCP performance. A performance comparison between TR and RO is discussed. Based on this performance comparison, a generic adoptive routing technique is proposed.