350-601 Storage Network Practice Question
An engineer is designing a SAN extension over a WAN link using FCIP. The link has high latency (50 ms RTT). Which configuration is most critical to maintain performance?
⚠ Common exam trap
Cisco often tests the misconception that buffer-to-buffer credits (BB_credits) are the primary flow control for FCIP, when in fact TCP window sizing is the critical parameter for high-latency WAN links.
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
✓
Configure a large TCP window size.
FCIP encapsulates Fibre Channel frames over TCP/IP. High latency (50 ms RTT) means the TCP sender must wait longer for acknowledgments, which can stall the connection if the TCP window is too small. A large TCP window size (e.g., using window scaling per RFC 1323) allows more data to be in flight before requiring an ACK, thereby maintaining throughput and preventing performance collapse on high-latency WAN links.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Configure a large TCP window size.
Why this is correct
Window scaling allows more data in flight, improving throughput over high-latency links.
- ✗
Enable compression on the FCIP tunnel.
Why it's wrong here
Compression reduces bandwidth but does not address latency.
- ✗
Increase the buffer-to-buffer credits.
Why it's wrong here
Buffer credits are for FC links, not FCIP tunnels.
- ✗
Reduce the TCP MSS to 512 bytes.
Why it's wrong here
Smaller MSS increases overhead and reduces efficiency.
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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.