Future Network designs - Vmware Access / Storage

Hello Guys,

I'm working on a Cisco ACI project which is suiting me a lot, it simplifies the connection to the access layer (Server hosts).

Now we are a bit in a struggle on our "older" network that's running on Cisco NX-OS Nexus switches. We are using 7000 series as a core switch in both of our data centers. So a vPC cluster per data center of 2 7000's.

The 7000's are connecting to Nexus 5K/9K as the access switches. At this time the whole data center network is layer 2, so the vlan's are spanned where they need to be (or to much). This design is getting outdated as we look to the future.

But what is that future, i have seen some designs on Cisco / Juniper / ... On where we talk about a Layer 3 data center with Layer 2 encapsulated, like Cisco ACI under the hood.

Now my question is: How are you guys working toward this? Does your data center network also look like a big layer 2 spanning hole? How do you manage your access layer to the hosts, let's say you have a mixed environment between ESXi hosts and also storage hosts (Unity, ScaleIO,...). I would like to migrate towards a full layer 3 environment anywhere i can on even the NX-OS networks. I'm trying to push for a Spine/Leaf with the manual configuration if ACI is not preffered.

How are you guys faring in this discussions, what were the blocking points? How did you overcome some of them? For example our Vmware team likes the spanning of vlan's because it's easy and fast. But spanning spanning-tree domains everywhere....