OSPF Dead Timer Reset

Overview

RFC 4222 Recommendation 2 advises that when packet prioritization is not feasible, an OSPF implementation should refresh the neighbor inactivity (dead) timer upon receipt of any valid OSPF unicast packet, or any OSPF packet sent to AllSPFRouters on a point-to-point link. This prevents unnecessary adjacency loss when Hello packets are delayed or dropped due to congestion.

Behavior

When ip ospf dead-timer-reset any-control is enabled, OSPF resets the neighbor inactivity timer upon receipt of:

  • Any valid unicast OSPF control packet

This extends adjacency lifetime even when Hello packets are delayed by low-speed links or control-plane congestion. The default behavior is to reset the dead timer only upon receipt of Hello packets.

Implementation Notes

  • The logic is implemented in the neighbor receive path.

  • Only packets that pass basic validation reset the timer.

  • The feature is enabled per-interface under the OSPF daemon.

  • The no form restores the default Hello-only behavior.

  • Note RFC 4222 Cautions this may interact with RFC 4222 recommendation 1 see the RFC for details.

References