CCIE Data Center (legacy) — Question 107

Which statement describes the graceful restart capability in Cisco NX-OS Software?

Answer options

• A. In NX-OS Software, the OSPFv2 graceful restart extension is Cisco proprietary and is only compatible with other Cisco routers.
• B. A graceful restart allows OSPFv2 to remain in the data forwarding path through a process restart. When OSPFv2 needs to restart, it first sends a type 8 LSA, which includes a grace period that tells NSF helpers to keep all LSAs that originated from the restarting interface.
• C. Graceful restart helps keep an NX-OS system forwarding traffic transparently even if it experiences a cold reboot.
• D. If the restarting OSPFv2 interface does not come back up before the end of the grace period, or if the network experiences a topology change, the OSPFv2 neighbors tear down adjacency with the restarting OSPFv2 interface and treat it as a normal OSPFv2 restart.
• E. OSPFv3 graceful restart must be disabled before doing an ISSU.

Correct answer: D

Explanation

The correct answer is D because it accurately describes the behavior of OSPFv2 during a graceful restart, including the actions taken if the interface does not recover in time. Option A is incorrect as graceful restart can work with non-Cisco devices, while B and C misinterpret the function of graceful restart in OSPFv2. Option E is unrelated to the graceful restart discussion and focuses on OSPFv3.