Using EBGP instead of an IGP (OSPF or IS-IS) in leaf-and-spine data center fabrics is becoming a best practice (read: thing to do when you have no clue what you’re doing). The usual argument defending this design choice is “BGP scales better than OSPF or IS-IS”.
from http://blog.ipspace.net/2018/06/is-ebgp-really-better-than-ospf-in-leaf.html
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