Which Cisco ACI concept allows the integration of Layer 4 - Layer 7 devices into the traffic flow without the device being the default gateway for servers?

The integration of Layer 4 - Layer 7 devices, such as firewalls or load balancers, into the traffic flow in a Cisco ACI environment is effectively facilitated through the Service Graph concept. A Service Graph allows for the modular configuration and chaining of these services within the data path, ensuring that the devices can inspect and manipulate traffic without needing to be the default gateway for servers.

By utilizing Service Graphs, network architects can define the order of services (e.g., traffic needs to go through a firewall before a load balancer) and specify how traffic flows between different endpoints. This architecture offers flexibility and scalability, as it can adapt to changes in network topology or service requirements without disrupting server configurations.

In this context, Service Graphs are essential for maintaining data center efficiency while integrating complex service layers, enabling improved control over security and performance.