In Figure 4, we can see a typical deployment with two spines and three leaves. The Nexus 9500 modular switches are deployed at the top of the topology and act as spines, which in a traditional three-tiered network design would be the aggregation or core switches. Line cards are used to provide the ASICs (application-specific integrated circuitry) required for ACI. There are different line cards available, so make sure you are not purchasing a card that is NX-OS mode only.
The next component is the leaf switches. These are the Nexus 9300-series switches.
The spines connect to the leaves through 40 GE ports, but the spines and leaves are never connected (spine to spine or leaf to leaf).
Figure 4
We can also extend the network, ...
