ROTIO+: A Modified ROTIO for Nested Network Mobility

Abstract

The NEMO Basic Support (NBS) protocol ensures session continuity for all nodes in a moving network by maintaining a tunnel between Mobile Router (MR) and its Home Agent (HA). The NBS protocol, however, suffers from sub-optimality problem in routing, which gets amplified as the level of nesting increases [4]. The ROTIO [5] is a route optimization scheme for nested NEMO that restricts the number of tunnels to two thereby alleviating the pinball routing problem to a great extent. In this paper, we propose ROTIO+, a simple but practical extension of ROTIO scheme, to further reduce the number of tunnels to one in nested NEMO. In ROTIO+ scheme, the MR uses two binding updates (BUs): one to its HA and the other to the Top Level Mobile Router (TLMR). In the BU to its HA, it provides both the Care of Address (CoA) and Home Address (HoA) of the TLMR. Under normal circumstances, the HA routes all packets for the MR to the CoA of the TLMR. When the QoS decreases beyond a threshold i.e. the TLMR is changing the point of attachment, the HA sends the packet to the HoA of the TLMR. Thus, the scheme limits the number of visits to HA to one for a nested network and also has a fall back scheme when the TLMR changes point of attachment. The results show that it is an effective solution for route optimisation problem in nested NEMO.