Multi-Pod Connectivity via External L3
L3out is used to provide external connectivity in ACI Multi-Pod fabric deployment. Below figure shows how three pods are inter connected each other.
While doing this type of connection it can cause Asymmetric inbound and outbound traffic flows. This is because same external prefix was injected inside the multi-pod from each L3-Out connection and endpoints deployed in a given Pod would always leverage the local L3Out connection to send traffic to external destinations. If endpoints belonging to the same BD are connected across all the Pods of the Multi-Pod fabric, inbound traffic may be received via any of the deployed L3Out connections.