Routing Loops in Mobile Heterogeneous Ad Hoc Networks

Routing loops accounts for a fair share of packet loss in mobile networks, particularly so for heterogeneous mobile networks. Loops occur when nodes build routes based on inconsistent topology databases. The inconsistency is caused by, but not limited to, dissimilar transmission delay, lost signaling messages, mobility, traffic load, and dissimilar frequency for route update messages. The latter cause is a consequence of optimization of control traffic overhead in heterogeneous networks. These networks are networks that consist of links, or network segments, based on radios with unlike transmission technologies. Such networks typically operate in areas that enforce network topologies with non-optimal radio degree for some of the network types. This paper studies the phenomenon of routing loops in mobile heterogeneous networks. It is shown where the loops occur. Methods to reduce the occurrence of the loops, and ways to do local repair, are proposed.