Cisco APIC Layer 3 Networking Configuration Guide, Release 6.2(x)

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Cisco APIC Layer 3 Networking Configuration Guide, Release 6.2(x)

Configuring ACI layer 3 outside network connections

Updated: April 17, 2026

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Describes the workflow for configuring a Layer 3 Outside (L3Out) network connection in ACI environments.

Summary

The key components involved in configuring ACI Layer 3 outside network connections are:

  • Administrator: Configures the L3Out network connection with proper access privileges

  • Infrastructure security domain: Provides read/write access control for configuration

  • Target leaf switches: Physical network devices with the necessary interfaces for external connectivity

  • Layer 3 Outside (L3Out): External network connection that enables routing between ACI fabric and external networks

Workflow

Figure 1. Layer 3 outside network connection
The diagram illustrates the stages involved in configuring Layer 3 outside network connections in an ACI environment, highlighting prerequisites and the role of target leaf switches for external connectivity.

These are the stages of configuring ACI Layer 3 outside network connections:

  1. Prerequisites: The administrator ensures proper access and infrastructure availability.

    • Ensure that you have read/write access privileges to the infra security domain.

    • Ensure that the target leaf switches with the necessary interfaces are available.

  2. Configuration selection: The administrator chooses the appropriate L3Out scenario based on consumption requirements.

    • For an L3Out that will be consumed within a single tenant, follow the instructions for configuring BGP or OSPF.

    • For an L3Out that will be consumed (shared) among multiple tenants, follow the "Shared Layer 3 Out" guidelines.

    • For an L3Out transit routing use case, follow ACI transit routing instructions.

      Note: This feature requires APIC release 1.2(1x) or later.