The correct answer is that the vPC peer-link carries both data and control traffic. This is because the peer-link serves as the backbone of the vPC domain, forwarding data traffic such as traffic from orphan ports or traffic that must traverse the link for Layer 2 forwarding, while simultaneously transporting control traffic like vPC keepalive messages and Cisco Fabric Services (CFS) synchronization. On the Cisco DCCOR 350-601 exam, this concept tests your understanding of how the peer-link enables the two Nexus switches to operate as a single logical entity for downstream devices, ensuring loop-free multipathing. A common trap is assuming the peer-link only carries data or only control traffic, or confusing it with the separate keepalive link. Memory tip: think of the peer-link as the "highway" for both cargo (data) and signals (control)—if either is missing, the vPC domain breaks.
350-601 Network Practice Question
This 350-601 practice question tests your understanding of network. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A data center uses VPC between two Nexus switches. Which statement is true about the VPC peer-link?
Why wrong: The peer-link is typically a port-channel (multiple links) for redundancy and bandwidth.
B
It carries only control traffic.
Why wrong: The peer-link also carries data traffic, especially traffic that needs to cross to the other VPC peer.
C
It is used only for orphan ports.
Why wrong: Orphan ports are one use case, but the peer-link also carries control traffic and data for other scenarios.
D
It carries both data and control traffic.
The VPC peer-link is used for both control plane communication (e.g., configuration synchronization) and data plane forwarding (e.g., for orphan ports or traffic requiring cross-peer forwarding).
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It carries both data and control traffic.
The VPC peer-link is a critical component in a vPC domain, carrying both data traffic (e.g., traffic from orphan ports or traffic that must traverse the peer-link for forwarding) and control traffic (e.g., vPC keepalive messages and Cisco Fabric Services (CFS) synchronization). This dual role ensures that the two Nexus switches operate as a single logical entity for the downstream devices, providing loop-free Layer 2 multipathing.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
It must be a single link.
Why it's wrong here
The peer-link is typically a port-channel (multiple links) for redundancy and bandwidth.
✗
It carries only control traffic.
Why it's wrong here
The peer-link also carries data traffic, especially traffic that needs to cross to the other VPC peer.
✗
It is used only for orphan ports.
Why it's wrong here
Orphan ports are one use case, but the peer-link also carries control traffic and data for other scenarios.
✓
It carries both data and control traffic.
Why this is correct
The VPC peer-link is used for both control plane communication (e.g., configuration synchronization) and data plane forwarding (e.g., for orphan ports or traffic requiring cross-peer forwarding).
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that the peer-link is only for control traffic, but the trap here is that candidates forget the peer-link also carries data traffic for orphan ports and for forwarding when a vPC member link fails.
Trap categories for this question
Scenario analysis trap
Orphan ports are one use case, but the peer-link also carries control traffic and data for other scenarios.
Detailed technical explanation
How to think about this question
Under the hood, the peer-link uses a dedicated VLAN (typically VLAN 1 by default, but configurable) for control-plane communication via CFS, while data-plane traffic uses the same port-channel. A subtle behavior is that the peer-link must be configured as a trunk allowing all VLANs used in the vPC domain, and it requires the 'spanning-tree port type network' command to avoid STP issues. In a real-world scenario, if the peer-link fails but the keepalive link remains up, the vPC secondary switch will suspend all vPC member ports to prevent loops, relying on the peer-link for data forwarding during normal operation.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network — This question tests Network — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: It carries both data and control traffic. — The VPC peer-link is a critical component in a vPC domain, carrying both data traffic (e.g., traffic from orphan ports or traffic that must traverse the peer-link for forwarding) and control traffic (e.g., vPC keepalive messages and Cisco Fabric Services (CFS) synchronization). This dual role ensures that the two Nexus switches operate as a single logical entity for the downstream devices, providing loop-free Layer 2 multipathing.
What should I do if I get this 350-601 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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