Cisco SAN Extension Topology for Long-Distance Data Centers
Short answer
B Native Fibre Channel SAN extension (specifically FCIP) must be used because the 510 km distance exceeds the physical reach of native FC optics, requiring IP encapsulation to traverse the WAN/MAN link.
Question
Key Takeaways
The main trap is confusing 'Native FC' with 'Local FC'; you must recognize that 'SAN extension' implies FCIP for distances >100km, whereas native FC optics max out around 80-100km.
Designing a Cisco SAN between data centers 510 km apart requires Native Fibre Channel SAN extension (FCIP) rather than native FC optics or unified fabric, as physical limits prevent direct long-distance FC connections.
Common mistake: Candidates often choose D (Unified Fabric) thinking it offers greater flexibility or distance support. However, Unified Fabric typically refers to FCoE within a data center or campus; extending it over 510km still requires IP encapsulation (FCIP), making 'SAN extension' the precise architectural term for the WAN link.
Expert Analysis
The Distance Constraint: Native FC vs. FCIP
The critical factor in this scenario is the 510 km separation between data centers. In Cisco SAN design, native Fibre Channel (FC) connectivity relies on physical optical transceivers and cabling that are strictly limited by distance due to signal attenuation and latency constraints. Typically, native FC links using long-reach optics (such as 16G or 32G LR/ER) are viable up to approximately 80–100 km. Attempting to run native FC signals over 510 km is physically impossible without repeaters, which do not exist for standard FC protocols in a transparent fabric mode.
Why Unified Fabric is Incorrect
Option D, Unified Fabric, refers to Cisco’s converged network architecture (typically involving FCoE over Ethernet). While it allows LAN and SAN traffic to share physical infrastructure, it still relies on the underlying transport medium. If that transport is Ethernet/WAN, it does not magically extend the physical layer limits of storage protocols. Furthermore, unified fabric is generally designed for intra-data center convergence, not inter-data center replication over metropolitan distances. As noted in community discussions, while some confuse "unified" with long-distance capability, the protocol overhead and physical layer limitations make it unsuitable for direct 510 km FC extension without encapsulation.
The Correct Solution: Native FC SAN Extension via FCIP
Although the option label says "native Fibre Channel SAN extension," in the context of 300-610 exam logic, this refers to the Cisco MDS 9710 platform capabilities when utilizing FCIP (Fibre Channel over IP). FCIP encapsulates FC frames within TCP/IP packets, allowing them to traverse WAN/MAN links across any distance, including 510 km. The MDS 9710 supports high-throughput extensions (up to 16 Gbps or more depending on licensing and hardware) suitable for backup and replication. This creates a logical SAN extension where the two fabrics appear connected, despite the physical distance exceeding native FC limits. Therefore, among the choices, B is the intended answer representing the technology category of SAN extension used here, distinct from local multi-switch or local unified fabric designs.
Exam Strategy
When evaluating SAN extension questions, always check the distance first. If the distance is greater than ~80-100 km, native FC optics are invalid. You must look for options involving FCIP or iSCSI. Do not select 'Unified Fabric' unless the question specifically asks about convergence within a single site or short campus links; for long-distance replication, focus on 'SAN Extension' technologies like FCIP or DWDM-based FC (if explicitly stated as such).
Frequently Asked Questions
Why can't we use native Fibre Channel optics for 510 km?
What does 'Native Fibre Channel SAN extension' mean in this context?
Community Votes
60% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 6 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 6
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Ayman_B 👍 2 Answered BIt converges LAN and SAN within the same fabric (FCoE), but is not designed for connecting data centers over long-distance WANs. D is wrong
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zeppie 👍 2 Answered BGoing with B. Unified fabric is tied to Ethernet, which is not supposed to span for such long distances.
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garza_javi 👍 1 Answered BFor connecting two geographically separated data centers over a 510 km WAN/MAN link with 16 Gbps bandwidth, native Fibre Channel SAN extension is the appropriate topology. It provides dedicated Fibre Channel connectivity between SAN fabrics for storage replication and backup.
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chad0128 👍 1 Answered DCisco devices can support native FC connections over various distances, depending on the specific switch and technology used. For example, Cisco's MDS 9710 switch can support up to 500km at 16GFC.
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CoAsT_x 👍 1 Answered Di also considered B, but the only way to go over a WAN/MAN link for FC would be FCIP or a Unified Fabric, not "native FC" ... i will go with D.
Show 1 more comment
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lurker8000 👍 1I will go with B.
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