Implementing LDP NSF Tasks
Question
Which two tasks must you perform when you implement LDP NSF on your network? (Choose two.)
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D. E.BE.
LDP (Label Distribution Protocol) Non-Stop Forwarding (NSF) is a feature that enables Label Switching Routers (LSRs) to maintain label information and forwarding state during a control plane switchover. This feature helps to reduce the impact of control plane failures and improve network availability.
When implementing LDP NSF on a network, there are two important tasks that need to be performed:
Implement direct connections for LDP peers: LDP uses TCP to establish a session between two LSRs to exchange label information. During an NSF event, when the control plane switches from the active RP (Route Processor) to the standby RP, the TCP connection is disrupted. To maintain the LDP session during the switchover, it is necessary to configure direct physical or logical connections between the active and standby RPs. This can be achieved through the use of cross-connects, Layer 2 circuits, or VLANs.
Enable NSF for the link-state routing protocol that is in use on the network: LDP NSF requires that the link-state routing protocol in use on the network also supports NSF. When an NSF event occurs, the link-state routing protocol must be able to maintain its database and forwarding state during the switchover. Examples of link-state routing protocols that support NSF include OSPF (Open Shortest Path First) and IS-IS (Intermediate System to Intermediate System).
Therefore, the correct answers to the question are B. Implement direct connections for LDP peers, and E. Enable NSF for the link-state routing protocol that is in use on the network.
Answers A. Enable NSF for BGP, C. Enable NSF for EIGRP, and D. Disable Cisco Express Forwarding are incorrect because BGP and EIGRP are not directly related to LDP NSF, and disabling Cisco Express Forwarding is not required for implementing LDP NSF.
