can only connect to leaf switches and are never
interconnected with each other. The ACI fabric provides
consistent low-latency forwarding across high-
bandwidth links (40 Gbps, 100 Gbps, and 400 Gbps).
Data traffic with the source and destination on the same
leaf switch is handled locally. When the traffic source
and destination are on separate leaf switches, they are
always only one spine switch away. The whole ACI fabric
operates as a single Layer 3 switch, so between a data
traffic source and destination, it will always be at most
one Layer 3 hop.
The configuration of the ACI fabric is stored in the APIC
using an object-oriented schema. This configuration
represents the logical model of the fabric. The APIC
compiles the logical model and renders the policies into a
concrete model that runs in the physical infrastructure.
Figure 9-2 shows the relationship between the logical
model, the concrete model, and the operating system
running on the switches.
Figure 9-2 Relationship Between the Logical Model,
the Concrete Model, and the Operating System
Each of the switches contains a complete copy of the
concrete model. When a policy that represents a