Dell N3200-ON EMC Networking N-Series Switches CLI Reference Guide version 6.7 - Page 1601

When NUD is triggered, neighbor solicitation PROBE packets (unicast and multicast) are sent periodically, separated by exponential binary values instead of the normal 1 second interval. This ensures that when the network (not just our router but more routers in the network) is congested, the NUD process for the existing STALE entries takes enough time before ultimately removing the cache entry through garbage collection. Without the exponential backoff timing for retransmissions, there is a higher probability that the cache entry is removed resulting in the disruption of the existing traffic. Another significant benefit of delayed neighbor solicitation retransmission is higher robustness against transient failures, such as spanning tree reconvergence and other layer 2 issues that can take many seconds to resolve. The exponential back-off calculation is next retransmission timer = (BACKOFF_MULTIPLE^solicit_attempt_num) *$RETRANS_TIMER + jittered value. The exponential backoff algorithm complies with draft-ietf-6man-impatientnud-02. Increase this value when large numbers of neighbors are present or when neighbors are not being discovered due to network events like spanning-tree re-convergence. Command History Introduced in version 6.2.0.1 firmware. Example console (config)#ipv6 nd nud retry 5 ipv6 nd other-config-flag Use the ipv6 nd other-config-flag command in Interface Configuration mode to set the "other stateful configuration" flag in router advertisements sent from the interface. Syntax ipv6 nd other-config-flag Layer 3 Routing Commands 1601