Looping in OLSRv2 in Mobile Ad-Hoc Networks, Loop Suppression and Loop Correction

Lee SPEAKMAN  Yasunori OWADA  Kenichi MASE  

IEICE TRANSACTIONS on Communications   Vol.E92-B   No.4   pp.1210-1221
Publication Date: 2009/04/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E92.B.1210
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Network
mobile ad-hoc network,  routing,  loops,  

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Transient routing loops have been observed to form in Mobile Ad-hoc Networks running the OLSRv2 proactive link-state routing protocol. The packets falling into loops impact the surrounding network thus degrading throughput even though only a small proportion of the traffic may enter these loops and only for a short time. This becomes significantly more evident when Link Layer Notification is used to catch broken links, inadvertently leading to an increase in the number of loops. Two methods of Loop Detection are introduced and are used to trigger either Loop Suppression by selectively and preemptively discarding the looping packets that are unlikely to reach their destination, or Loop Correction by the notification of the routing protocol to cut the link over which the packet is looping. The newly introduced Loop Suppression and Loop Correction techniques used with Link Layer Notification are shown to significantly increase network performance over plain OLSRv2 and OLSRv2 with Link Layer Notification.