Reducing Signaling Delay in Network Design - Exam 352-001: CCDE Written Exam

Actions to Minimize Signaling Delay in Network Design

Question

A network design includes a long signaling delay in notifying the Layer 3 control plane that an interface has failed.

Which two of these actions would reduce that delay? (Choose two.)

Answers

Explanations

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A. B. C. D.

AD.

The long signaling delay in notifying the Layer 3 control plane about a failed interface can cause network instability and potential downtime. Therefore, it's important to reduce this delay to maintain network availability and performance. Two actions that can reduce the delay are:

A. Enable lower data link layer recovery systems to have an opportunity to restore the interface: When a data link layer recovery system such as Spanning Tree Protocol (STP) or Link Aggregation Control Protocol (LACP) detects a failed interface, it can take immediate action to restore the interface, reducing the delay in signaling the failure to the Layer 3 control plane. Enabling these lower layer recovery systems can significantly reduce the time it takes to detect and restore a failed interface.

C. Reduce the time for the network to reconverge: Reconvergence is the process by which a network adjusts its routing or forwarding tables after a topology change, such as an interface failure. Reducing the time it takes for the network to reconverge can help minimize the delay in notifying the Layer 3 control plane about a failed interface. This can be achieved by using fast convergence protocols such as Rapid Spanning Tree Protocol (RSTP) or Bidirectional Forwarding Detection (BFD), which can quickly detect failures and update network paths.

B and D are not correct answers because:

B. Increasing the notification of interface flaps can generate more control plane messages and increase network overhead, which can impact network performance. It may also not be necessary if lower layer recovery systems are already in place to restore failed interfaces.

D. Increasing network stability is a desirable goal but may not directly address the issue of long signaling delay in notifying the Layer 3 control plane about a failed interface.