An Optimization for the MANET Neighborhood Discovery Protocol (NHDP)
draft-dearlove-manet-nhdp-optimization-01

Abstract

The link quality mechanism of the MANET Neighborhood Discovery Protocol (NHDP) enables "ignoring" some 1-hop neighbors if the measured link quality from that 1-hop neighbor is below an acceptable threshold, while still retaining the corresponding link information as acquired from HELLO message exchange. This allows immediate reinstatement of the 1-hop neighbor if the link quality later improves sufficiently. NHDP also collects information about symmetric 2-hop neighbors. However it specifies that if a link from a symmetric 1-hop neighbor ceases being symmetric, including while "ignored" as described above, then corresponding symmetric 2-hop neighbors are removed. This may lead to symmetric 2-hop neighborhood information being permanently removed (until further HELLO messages are received) if the link quality of a symmetric 1-hop neighbor drops below the acceptable threshold, even if only for a moment. This specification updates NHDP, and the Optimized Link State Routing Protocol version 2 (OLSRv2) to permit retaining, but ignoring, symmetric 2-hop information when the link quality from the corresponding 1-hop neighbor drops below the acceptable threshold. This allows immediate reinstatement of the symmetric 2-hop neighbor if the link quality later improves sufficiently, thus making the symmetric 2-hop neighborhood more "robust".

Authors

Christopher Dearlove
Thomas H. Clausen

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