Network Convergence Factors | CCDE Written Exam | Cisco

Improve Network Convergence

Question

You are designing a network to support data, voice and video.

Which two main factors will you address to improve network convergence? (Choose two.)

Answers

Explanations

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A. B. C. D.

BD.

Network convergence refers to the ability of the network to quickly and efficiently adapt to changes such as link or node failures, and re-establish the connectivity of the network. Convergence is critical in networks that support data, voice, and video traffic, as delays or disruptions can result in poor quality or loss of service.

The two main factors that can affect network convergence are:

  1. Failure detection delay: This refers to the time taken by the network to detect a failure, such as a link or node going down. The longer it takes for the network to detect a failure, the longer it will take for the network to initiate the convergence process.

To improve failure detection delay, techniques such as fast link and node failure detection, and the use of protocols like Bidirectional Forwarding Detection (BFD) can be employed. BFD provides a fast and reliable mechanism for detecting failures by detecting loss of connectivity between neighboring nodes.

  1. Routing table recalculation delay: This refers to the time taken by the network to recalculate the routing tables and determine new paths for traffic after a failure has been detected. The longer it takes for the network to recalculate the routing tables, the longer it will take for the network to re-establish connectivity.

To improve routing table recalculation delay, techniques such as pre-calculated alternate paths, fast rerouting, and the use of protocols like Fast Convergence (FC) can be employed. Fast rerouting provides a mechanism for quickly switching traffic to pre-calculated alternate paths when a failure occurs, while FC provides a mechanism for quickly converging the routing tables.

Event propagation delay and forwarding engine update delay are also factors that can affect network convergence. However, they are not the main factors that need to be addressed to improve network convergence. Event propagation delay refers to the time taken for network devices to receive and process information about a failure. Forwarding engine update delay refers to the time taken by the forwarding engine to update its forwarding tables after a failure has been detected. While these factors can affect network convergence, their impact is generally lower compared to failure detection delay and routing table recalculation delay.