HPE7-A04 · Question #25
In Spine and Leaf Design that involves the following: - 8360 12-P 100G Spine Switches - 8360 48-P 10G RJ45 Leaf Switches - 100G SR4 Optical connections between Spine and Leafs Spine Switches = 8360…
The correct answer is A. Solution can scale to 6 total racks using the same subscription rates. Option A is correct because each Spine switch has only 4 available 100G QSFP28 ports, and since every Leaf switch requires one dedicated uplink to each Spine, the Spine port count is the binding constraint - capping the design at 4 Leaf switches. Adding those 4 Leaf rack…
Question
In Spine and Leaf Design that involves the following:
- 8360 12-P 100G Spine Switches
- 8360 48-P 10G RJ45 Leaf Switches
- 100G SR4 Optical connections between Spine and Leafs
Spine Switches = 8360 12-port 100G QSFP28 (F-B airflow) Each Spine Switch uses:
- 1 x 100G QSFP28 SR4 Optic to each Leaf switch
Each Leaf Switch uses:
- 1 x 100G QSFP28 SR4 Optic to each Spine switch
- 2 x 100G 1M DAC for ISL
- 1 x 10G RJ45 for Keepalive
Each Spine switch has 4 available 100G QSFP28 interfaces. What is the solution scalability?
Options
- ASolution can scale to 6 total racks using the same subscription rates.
- BSolution can scale to 10 total racks using the same subscription rates.
- CSolution can scale to 4 total racks using the same subscription rates.
- DSolution can scale to 12 total racks using the same subscription rates.
How the community answered
(28 responses)- A50% (14)
- B7% (2)
- C14% (4)
- D29% (8)
Explanation
Option A is correct because each Spine switch has only 4 available 100G QSFP28 ports, and since every Leaf switch requires one dedicated uplink to each Spine, the Spine port count is the binding constraint - capping the design at 4 Leaf switches. Adding those 4 Leaf rack positions to the 2 Spine switch rack positions gives 4 + 2 = 6 total racks.
Option C (4 racks) is a common trap - it only counts the 4 Leaf connections and forgets to include the 2 Spine switch rack positions in the total. Option D (12 racks) confuses the total port count of the 8360 12-port switch with the available port count; using all 12 ports would ignore the ports already consumed by other functions. Option B (10 racks) has no basis in the given numbers - it would require far more available uplink ports per Spine than the design provides.
Memory tip: Think "4 + 2 = 6" - the 4 available Spine ports drive the Leaf count, then add the 2 Spine racks. If you catch yourself using the total port count (12) instead of the available count (4), you've fallen for the classic distractor.
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