Hello @Heinz Kern
The scalability limit of 500 EPGs per tenant in a multitenant environment is a recommendation from Cisco and is based on best practices to ensure optimal performance and stability of the ACI fabric. However, exceeding this limit may not necessarily cause an issue if the fabric is properly designed and configured.
In your case, it's possible that the L2 fabric without routing enabled is allowing for the larger number of EPGs in one tenant without any warning. However, if one EPG in the tenant is later enabled for routing, it may cause issues with performance and stability as the number of endpoints and associated policy will increase.
Best regards
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