350-501 · Question #292
After a series of unexpected device failures on the network, a Cisco engineer is deploying NSF on the network devices so that packets continue to be forwarded during switchovers. The network devices…
The correct answer is C. implement an L2VPN with the failover peer to share state Information between the active and. To deploy NSF on devices separated across two data centers, the engineer must implement an L2VPN with the failover peer to facilitate state information sharing between the active and standby forwarding engines, ensuring uninterrupted packet forwarding.
Question
After a series of unexpected device failures on the network, a Cisco engineer is deploying NSF on the network devices so that packets continue to be forwarded during switchovers. The network devices reside in the same building, but they are physically separated into two different data centers. Which task must the engineer perform as part of the deployment?
Options
- Aimplement OSPF to maintain the link-state database during failover.
- Bimplement VRFs ana specify the forwarding instances that must remain active during failover.
- Cimplement an L2VPN with the failover peer to share state Information between the active and
- Dimplement Cisco Express Forwarding to provide forwarding during failover
How the community answered
(52 responses)- A6% (3)
- B10% (5)
- C83% (43)
- D2% (1)
Why each option
To deploy NSF on devices separated across two data centers, the engineer must implement an L2VPN with the failover peer to facilitate state information sharing between the active and standby forwarding engines, ensuring uninterrupted packet forwarding.
While OSPF is a routing protocol that can be NSF-aware, simply implementing OSPF does not describe the specific state synchronization mechanism required between physically separated active and standby control planes for NSF.
VRFs (Virtual Routing and Forwarding) create isolated routing instances on a single router but do not provide the inter-device state synchronization required for NSF between physically separated active and standby forwarding engines.
Non-Stop Forwarding (NSF) requires seamless state synchronization between active and standby control planes to ensure continuous packet forwarding during a switchover. When devices are physically separated, an L2VPN can provide the necessary connectivity and mechanism to exchange and synchronize this critical state information, enabling the standby forwarding engine to take over without traffic disruption.
Cisco Express Forwarding (CEF) is a fundamental prerequisite for NSF, as it maintains the Forwarding Information Base (FIB) to enable packet forwarding during control plane switchovers. However, CEF itself does not provide the state synchronization mechanism between active and standby peers.
Concept tested: NSF deployment requirements for physically separated systems
Source: https://www.cisco.com/c/en/us/td/docs/ios/iproute/configuration/guide/irg_nsf_ss_feat_chap.html
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