I am currently working with a client to revamp their data center. They are currently using Cisco 6500 switches. I am planning to propose them a layer 3 network but there is one thing i dont understand. If customer has overlapping subnets across the racks, how can we manage that using layer 3 bgp/ospf between leaf and spine? (routing on the host is not an option here since customer is too cisco focused).
Since this is a revamp we cannot go with a big bang approach from day 1 by advising them to keep one subnet per rack. How does layer 3 design works with overlapping subnets between racks?