If you’re coming from the Cisco Nexus world, the table below will help with the different terminology.
| ACI | Nexus |
|---|---|
| Tenant | VDC |
| Bridge Domain (BD) | Subnet / SVI |
| End Point Group (EPG) | Broadcast Domain / VLAN / Private VLAN |
| Contracts | ACLs |
| L2 External EPG | 802.1Q Trunk |
| L3 External EPG | L3 Routed Link |
It will look something like this when you lay it all out:
Tenant > Global VRF/Routing Table and Protocol > VLAN 10 (BD) > VLAN 10 (EPG)
Tenant > Global VRF/Routing Table and Protocol > VLAN 20 (BD) > VLAN 20 (EPG)
Contracts are used to control traffic between EPGs in the ACI fabric:
VLAN 10 (EPG) <——CONTRACT——> VLAN 20 (EPG)