It seems in the early versions of ACI Spines connected to leaf switches only, I am reading this is no longer the case. Can Spine switches connect out to the traditional network and basically take the place of border leafs? I am not quite understanding this article: https://www.mvankleij.nl/post/aci_topology_hardware/
Ok so Spines connect to an IPN which is strictly for Multi-site ACI pod deployments. I have also read only OSPF is supported from the IPN switches across multi-sites. Not sure why only OSPF, seems novice...Also seems like Multicast is a big player in multi-site pods. I get that the role of the spine is route leaf to leaf traffic...but you would think the Spines were the entry and exit point of the traditional network and not border leafs. Just like back in the day 2ks would connect to 5k, 5ks connected to 7ks, 7ks connected to campus cores like 6500s.