350-601 Storage Network Practice Question
An engineer is deploying FCoE on a Cisco Nexus 9000v switch in a converged network. The storage array is connected via native Fibre Channel to an MDS switch, and the MDS is connected to the Nexus using an FCoE link. The engineer creates a virtual Fibre Channel (VFC) interface on the Nexus, binds it to an Ethernet interface, and maps VSAN 200 to VLAN 200. The MDS side has an FCoE port configured and enabled. Servers connected to the Nexus with FCoE initiators can successfully log into the storage targets, but performance is very poor and intermittent. The engineer checks for drops on all interfaces and finds none. The engineer also verifies that the FCoE VLAN is not blocked by spanning tree. What is the most likely cause of the performance issue?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Ethernet interface MTU is set to 1500 instead of 2500.
FCoE requires a jumbo MTU (typically 2500 bytes) to encapsulate Fibre Channel frames without fragmentation. An MTU of 1500 forces fragmentation and reassembly, causing retransmissions and poor performance. Option B is incorrect because the engineer verified that the FCoE VLAN is not blocked by spanning tree. Option C is incorrect because servers can log in, indicating FCoE is enabled on the MDS interface. Option D is incorrect because the VFC binding was already verified as correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The Ethernet interface MTU is set to 1500 instead of 2500.
Why this is correct
FCoE requires jumbo frames; 1500 MTU causes fragmentation.
- ✗
The FCoE VLAN is blocking spanning tree.
Why it's wrong here
The engineer already verified that spanning tree is not blocking the VLAN.
- ✗
The MDS has not enabled FCoE on the interface.
Why it's wrong here
Login works, so FCoE is enabled on the MDS.
- ✗
The VFC interface is not bound to the correct port-channel.
Why it's wrong here
Binding to a port-channel is not necessary for single Ethernet links.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-601 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-601 exam.