OSPFv3 GR

The NetEngine 8000 F can be configured as a GR helper rather than a GR restarter.

Graceful restart (GR) is a technology used to ensure proper traffic forwarding, especially the forwarding of key services, during the restart of routing protocols.

Without GR, the master/slave main control board switchover due to various reasons leads to transient service interruption, and as a result, route flapping occurs on the whole network. Such route flapping and service interruption are unacceptable on large-scale networks.

GR is one of the high availability (HA) technologies which comprise a series of comprehensive technologies, such as fault-tolerant redundancy, link protection, faulty node recovery, and traffic engineering technologies. As a fault-tolerant redundancy technology, GR is widely used to ensure non-stop forwarding of key data during the master/slave main control board switchovers and system upgrade.

In GR mode, the forwarding plane continues data forwarding during a restart, and operations on the control plane, such as re-establishment of neighbor relationships and route calculation, do not affect the forwarding plane, preventing service interruptions caused by route flapping and improving network reliability.

Comparison Between Master/Slave Main Control Board Switchovers with and Without GR

**Table 1** Comparison between master/slave main control board switchovers with and without GR
Master/Slave Main Control Board Switchovers Without GR	Master/Slave Main Control Board Switchovers with GR
OSPFv3 neighbor relationships are reestablished. Routes are recalculated. FIB entries change. The entire network detects route changes, and route flapping occurs for a short period of time. Packets are lost during forwarding, and services are interrupted.	OSPFv3 neighbor relationships are reestablished. Routes are recalculated. FIB entries remain unchanged. Except the neighbors of the router on which a master/slave main control board switchover occurs, other routers do not detect route changes. No packets are lost during forwarding, and services are not affected.