When determining the oversubscription ratio for an IP fabric, which two statements are true? (Choose two.)

Question

Options

• ARemoving spine nodes from the IP fabric increases the oversubscription ratio.
• BRemoving leaf nodes from the IP fabric increases the oversubscription ratio.
• CAdding spine nodes to the IP fabric decreases the oversubscription ratio.
• DAdding leaf nodes to the IP fabric decreases the oversubscription ratio.

• A
  73% (36)
• B
  8% (4)
• D
  18% (9)

Explanation

In a spine-leaf IP fabric, oversubscription is driven by the ratio of downlink (host-facing) bandwidth to uplink (spine-facing) bandwidth. Removing spine nodes (A) reduces the number of uplinks available from each leaf, shrinking the uplink bandwidth and forcing more traffic to compete for fewer paths - this raises the oversubscription ratio. Conversely, adding spine nodes (C) gives each leaf more uplinks to the spine layer, expanding uplink bandwidth and lowering the ratio.

Options B and D are wrong because changing the number of leaf nodes scales both downlinks and uplinks proportionally - each new or removed leaf brings its own host ports and its own uplinks to every spine, so the overall ratio stays the same.

Memory tip: Think of spines as highway lanes - more lanes (spines) means less congestion and a lower oversubscription ratio; fewer lanes means more congestion and a higher ratio. Leaves just add more on-ramps and more lanes simultaneously, so they cancel out.

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