Limitations of NSR
- Configurations that occur before the switchover are lost due to the CLI synchronization.
- NSR does not support virtual links.
- Changes in the neighbor state or interface state before or during a switchover do not take effect.
- Traffic counters are not synchronized because the neighbor and LSA database counters are recalculated on the standby module during synchronization.
- LSA acknowledging is delayed because it has to wait until standby acknowledging occurs.
- Depending on the sequence of redistribution or new LSAs (from neighbors), the LSAs accepted within the limits of the database may change after switchover.
- In NSR hitless failover, after switchover, additional flooding-related protocol traffic is generated to the directly connected neighbors.
- OSPF startup timers, database overflow, and max-metric, are not applied during NSR switchover.
- Devices may generate OSPF log messages or reset OSPF neighbor timers, but these issues do not cause any OSPF or traffic disruption.