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)

Direct traffic forwarding

Updated: April 17, 2026

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Direct traffic forwarding enables remote leaf switches to forward traffic directly across remote locations. Feature support, default behavior, and configuration workflows depend on the software release running on the remote leaf switches.

Direct traffic forwarding is a fabric feature that improves data-path efficiency for remote leaf switches. The feature is supported beginning with Release 4.1(2) as described in Remote leaf switch behavior in Release 4.1(2). Beginning with Release 5.0(1), it is enabled by default and cannot be disabled. The procedure for enabling or disabling the feature depends on the software release running on the remote leaf switches.

  • Supported beginning with Release 4.1(2).

  • Enabled by default beginning with Release 5.0(1).

  • Configured through specific upgrade or downgrade procedures based on the software release running on the remote leaf switches.

Direct traffic forwarding configuration requirements

The procedure for managing direct traffic forwarding depends on the software release running on the remote leaf switches:

  • If the remote leaf switches run Release 4.1(2) or later and have never run a release earlier than Release 4.1(2), follow the "Configure the pod and fabric membership for remote leaf switches using a wizard" procedure.

  • If the remote leaf switches run a release earlier than Release 4.1(2), follow the "Upgrade the remote leaf switches and enable direct traffic forwarding" procedure. Upgrade the switches to Release 4.1(2) or later, complete the required configuration, and enable direct traffic forwarding.

  • If the remote leaf switches run Release 4.1(2) or later with direct traffic forwarding enabled and you want to downgrade to a release earlier than Release 4.1(2), follow the "Disable direct traffic forwarding and downgrade the remote leaf switches" procedure. Disable direct traffic forwarding before you downgrade the switches.

  • If the remote leaf switches run a release earlier than Release 5.0(1) and you want to upgrade to Release 5.0(1) or later:

    1. If the remote leaf switches run a release earlier than Release 4.1(2), first upgrade them to Release 4.1(2) and enable direct traffic forwarding by following the "Upgrade the remote leaf switches and enable direct traffic forwarding" procedure.

    2. After the remote leaf switches run Release 4.1(2) with direct traffic forwarding enabled, upgrade them to Release 5.0(1) or later.

  • If the remote leaf switches run Release 5.0(1) or later, where direct traffic forwarding is enabled by default, you can downgrade to either of the following releases that support direct traffic forwarding:

    • Release 4.2(x)

    • Release 4.1(2)

    After the downgrade, the direct traffic forwarding state depends on the configuration before the downgrade:

    • If Routable Subnets and Routable Ucast were enabled for all pods before the downgrade, direct traffic forwarding remains enabled.

    • If Routable Subnets was enabled for all pods but Routable Ucast was not enabled, direct traffic forwarding is disabled after the downgrade.