UCS IOM to Fabric Interconnect Storage Connectivity
Short answer
C UCS: two-port PortChannel from each IOM to each fabric interconnect
Question
Key Takeaways
The common trap is assuming that SAN port-channeling works with all storage arrays; however, direct-attach arrays typically lack this support, necessitating a specific link count.
This question evaluates the correct cabling strategy for connecting Cisco UCS IOM 2408 Fabric Extenders to Cisco 6454 Fabric Interconnects in a direct-attach Fibre Channel storage environment.
Common mistake: Option B (four-port back-to-back) or D (four-port PortChannel) are incorrect because they assume SAN port-channel support which direct-attach storage usually lacks, and back-to-back is not a standard interconnect method here.
Expert Analysis
Why the Answer Is Correct
The correct strategy is two-port PortChannel from each IOM to each fabric interconnect (Option C). The Cisco UCS IOM 2408 provides four 10 GbE ports. In a design where the storage is direct-attach Fibre Channel (not connected via MDS/NXOS switches), the IOM connects to the Fabric Interconnects using Ethernet uplinks. Since direct-attach storage arrays do not support SAN port-channeling (which requires FC switch support like on MDS/NXOS), you cannot bundle more links than necessary or assume multi-pathing protocols that rely on switch-side channeling. The standard best practice for redundancy and bandwidth in this specific 'direct-attach' context without FC switch involvement is to use two ports per connection (one to each FI) forming a PortChannel, leaving two ports available or unused depending on the exact model constraints, but critically, it avoids the unsupported SAN port-channel.
Why the Other Options Are Wrong
Option A suggests 802.1q trunks, which is a VLAN tagging concept, not a physical connectivity strategy for the IOM-FI link itself. Option B suggests a 'back-to-back' PortChannel, which is technically nonsensical in this topology as it implies connecting the IOM directly to another IOM or a non-existent peer without the FI. Option D suggests a four-port PortChannel; while physically possible if all ports were used, it doesn't provide the necessary cross-FI redundancy if the design implies connecting to both FIs, and more importantly, community consensus highlights that direct-attach scenarios often restrict the logical channeling capabilities compared to switched SAN environments.
Community Comment Notes
Commenters consistently agree on C. One user noted, 'Only MDS and NXOS support san-port-channel. Direct attach storage does not,' highlighting the key constraint. Another user succinctly stated, '2 for IOM 4 for Fiber Channel,' reinforcing the split between IOM uplink ports and FC controller ports.
Exam Strategy
Always distinguish between switched SAN (MDS/NXOS) and direct-attach storage when evaluating port-channel options. If direct-attach, SAN port-channeling is generally not supported, limiting your uplink strategy.
Frequently Asked Questions
Why can't we use a four-port PortChannel?
What is the role of the 32G FC ports?
Community Votes
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
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CoAsT_x 👍 1 Answered CHas to be C. Only MDS and NXOS support san-port-channel. Direct attach storage does not.
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Fcpoultry 👍 2 Answered C2 for IOM 4 for Fiber Channel
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lurker8000 👍 1Agree on C for this one.
Reader comments & corrections
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