Cisco APIC Layer 2 Networking Configuration Guide, Release 6.2(x)

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Cisco APIC Layer 2 Networking Configuration Guide, Release 6.2(x)

Reflective relay (802.1Qbg)

Updated: July 7, 2026

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Describes a switching option that forwards all traffic to an external switch for policy application and processing.

Reflective relay is a switching option that

  • forwards all traffic to an external switch, which then applies policy and sends the traffic back to the destination or target VM on the server as needed

  • provides packet replication to each VM locally on the server for broadcast or multicast traffic, and

  • uses the tagless approach of IEEE standard 802.1Qbg with no local switching.

Reflective relay is available beginning with Cisco APIC Release 2.3(1). One benefit of reflective relay is that it leverages the external switch for switching features and management capabilities, freeing server resources to support the VMs. Reflective relay also allows policies that you configure on the Cisco APIC to apply to traffic between the VMs on the same server.

In the Cisco ACI, you can enable reflective relay, which allows traffic to turn back out of the same port it came in on. You can enable reflective relay on individual ports, port channels, or virtual port channels as a Layer 2 interface policy using the APIC GUI, NX-OS CLI, or REST API. It is disabled by default.

The term Virtual Ethernet Port Aggregator (VEPA) is also used to describe 802.1Qbg functionality.

Reflective relay support

Reflective relay supports the following:

  • IEEE standard 802.1Qbg tagless approach, known as reflective relay.

    Cisco APIC Release 2.3(1) release does not support the IEE standard 802.1Qbg S-tagged approach with multichannel technology.

  • Physical domains.

    Virtual domains are not supported.

  • Physical ports, port channels (PCs), and virtual port channels (vPCs).

    Cisco Fabric Extender (FEX) and blade servers are not supported. If reflective relay is enabled on an unsupported interface, a fault is raised, and the last valid configuration is retained. Disabling reflective relay on the port clears the fault.

  • Cisco Nexus 9000 series switches with EX or FX at the end of their model name.

Enable reflective relay using the GUI

Reflective relay is disabled by default; however, you can enable it on a port, port channel, or virtual port channel as a Layer 2 interface policy on the switch. You first configure a policy and then associate the policy with a policy group.

Before you begin

This procedure assumes that you have set up the Cisco Application Policy Infrastructure Controller (ACI) fabric and installed the physical switches.

Follow these steps to enable reflective relay using the GUI:

Procedure

  1. Choose Fabric > External Access Policies > > Interface Policies and then open the Policies folder.

  2. Right-click the L2 Interface folder and choose Create L2 Interface Policy.

  3. In the Create L2 Interface Policy dialog box, enter a name in the Name field.

  4. In the Reflective Relay (802.1Qbg) area, click enabled.

  5. Choose other options in the dialog box as needed.

  6. Click SUBMIT.

  7. In the Policies navigation pane, open the Policy Groups folder and click the Leaf Policy Groups folder.

  8. In the Leaf Policy Groups central pane, expand the ACTIONS drop-down list, and choose Create Leaf Access Port Policy Group, Create PC Interface Policy Group, Create vPC Interface Policy Group, or Create PC/vPC Override Policy Group.

  9. In the policy group dialog box, enter a name in the Name field.

  10. From the L2 Interface Policy drop-down list, choose the policy that you just created to enable Reflective Relay.

  11. Click Submit.

Enable reflective relay using the NX-OS CLI

Reflective relay is disabled by default; however, you can enable it on a port, port channel, or virtual port channel as a Layer 2 interface policy on the switch. In the NX-OS CLI, you can use a template to enable reflective relay on multiple ports or you can enable it on individual ports.

Before you begin

This procedure assumes that you have set up the Cisco Application Centric Infrastructure (ACI) fabric and installed the physical switches.

Follow these steps to enable reflective relay using the NX-OS CLI:

Procedure

Enable reflective relay on one or multiple ports:

Example:

This example enables reflective relay on a single port: 
apic1(config)# leaf 101
apic1(config-leaf)# interface ethernet 1/2
apic1(config-leaf-if)# switchport vepa enabled
apic1(config-leaf-if)# exit
apic1(config-leaf)# exit

Example:

This example enables reflective relay on multiple ports using a template: 
apic1(config)# template policy-group grp1
apic1(config-pol-grp-if)# switchport vepa enabled
apic1(config-pol-grp-if)# exit
apic1(config)# leaf 101
apic1(config-leaf)# interface ethernet 1/2-4
apic1(config-leaf-if)# policy-group grp1

Example:

This example enables reflective relay on a port channel: 
apic1(config)# leaf 101
apic1(config-leaf)# interface port-channel po2                 
apic1(config-leaf-if)# switchport vepa enabled
apic1(config-leaf-if)# exit
apic1(config-leaf)# exit
apic1(config)#

Example:

This example enables reflective relay on multiple port channels: 
apic1(config)# template port-channel po1
apic1(config-if)# switchport vepa enabled
apic1(config-if)# exit
apic1(config)# leaf 101
apic1(config-leaf)# interface ethernet 1/3-4
apic1(config-leaf-if)# channel-group po1 
apic1(config-leaf-if)# exit
apic1(config-leaf)# exit

Example:

This example enables reflective relay on a virtual port channel: 
apic1(config)# vpc domain explicit 1 leaf 101 102
apic1(config-vpc)# exit
apic1(config)# template port-channel po4
apic1(config-if)# exit
apic1(config)# leaf 101-102
apic1(config-leaf)# interface eth 1/11-12
apic1(config-leaf-if)# channel-group po4 vpc
apic1(config-leaf-if)# exit
apic1(config-leaf)# exit
apic1(config)# vpc context leaf 101 102
apic1(config-vpc)# interface vpc po4
apic1(config-vpc-if)# switchport vepa enabled