Cisco SD-WAN Packet Duplication Process

300-415 By islever Editorial Last updated

Configure Cisco Catalyst SD-WAN data plane

Short answer

C Copies of packets are sent over multiple WAN circuits to overcome packet loss.

Question

Which process is continued by Cisco SD-WAN when packet duplication is enabled?
  1. Additional headers are added to outgoing packets to perform custom routing policies.
  2. Dynamic traffic is compressed and signaled before it is forwarded though the WAN.
  3. Copies of packets are sent over multiple WAN circuits to overcome packet loss. Correct Answer
  4. Application traffic is analyzed to find patterns and enable custom detection rules.

Key Takeaways

This question tests the understanding of data plane reliability mechanisms, specifically how packet duplication mitigates loss without requiring retransmission at the application layer.

Packet duplication in Cisco Catalyst SD-WAN ensures reliability by sending copies of packets over multiple WAN circuits to overcome packet loss, maintaining application performance.

Common mistake: Learners often confuse packet duplication with compression (Option B) or custom routing headers (Option A), failing to recognize that duplication is a redundancy mechanism for loss mitigation.

Expert Analysis

Why the Answer Is Correct

Packet duplication is a feature designed to improve application availability and reduce jitter/loss on unreliable links. When enabled, the SD-WAN edge device creates identical copies of outgoing packets and sends them across different TLOCs (Transport Locators) or WAN circuits. The receiving end typically discards duplicates, ensuring the first successful packet is used, effectively overcoming transient packet loss.

Why the Other Options Are Wrong

Option A describes encapsulation or tunneling techniques used for routing policies, not duplication. Option B refers to compression algorithms which reduce bandwidth usage but do not inherently improve reliability through redundancy. Option D describes deep packet inspection or intrusion detection systems, which are security functions unrelated to the reliability mechanism of packet duplication.

Community Comment Notes

The community consensus strongly supports Option C as the correct answer. Users referenced official Cisco documentation confirming that "Packet duplication sends copies of packets... to overcome packet loss." Multiple commenters verified this behavior aligns with SD-WAN best practices for high-availability requirements.

Official Reference

https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/policies/ios-xe-17/policies-book-xe/packet-duplication.html

This link opens the official vendor documentation in a new tab.

Exam Strategy

Focus on the specific function of each data plane feature: duplication for reliability, compression for bandwidth efficiency, and encryption for security. Memorize the trade-offs between these features to avoid confusion during the exam.

Frequently Asked Questions

Does packet duplication increase bandwidth usage?

Yes, it significantly increases bandwidth consumption because duplicate traffic is transmitted on all selected paths.

When should I enable packet duplication?

Enable it only for critical applications where packet loss causes unacceptable jitter or latency, due to the high bandwidth cost.

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Community Votes

C
100%

100% of anonymous learners picked answer C. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 3 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 3

  1. Stacey 👍 1 Answered C
    See link below: https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/policies/ios-xe-17/policies-book-xe/packet-duplication.html#:~:text=Packet%20duplication%20sends%20copies%20of,one%20packet%20to%20the%20server.
  2. Gycu 👍 1 Answered C
    C is correct
  3. Stanleymahamadi 👍 1
    C correct

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