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5-stage Clos Example#

Network Diagram#

5-stage Clos

Assumptions#

  • Uplinks from Leaf to Spine are 100G
  • Servers can connect at either 10G or 25G
  • Support for single-homed or dual-homed servers (only impact is server density)
  • Leaf to Spine oversubscription calculations are based on 25G downlink and 100G uplink
  • Connections out of the fabric will come via a pair of Leaf nodes (Border Leafs)
  • Oversubscription ratio is 1:1 between Spine, Superspine and Border Leaf
  • Number of Border Leafs can scale out based on amount of North/South traffic

Details#
Spine node 7220-IXR-D3 (32xQSFP28 + 2xSFP+)
Leaf node 7220-IXR-D2 (48xSFP28+8xQSFP28)
Border Leaf node 7220-IXR-D3 (32xQSFP28 + 2xSFP+)
# of Spines per Pod 4
# of Leafs per Pod 16
# of Pods 4
# of Superspines 16
# of Border Leafs 2 (or more)
Max single-homed servers 3,072 (48*64)
Max dual-homed servers 1,536 (48*32)
Leaf-to-spine oversubscription 3:1