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)

Configure route summarization at L3out external EPG level using the GUI

Updated: April 17, 2026

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Configure route summarization associated to an L3Out External EPG to achieve route summarization towards L3Out peers using the GUI.

This task explains how to configure route summarization associated to an L3Out External EPG. Enabling route summarization using these configuration steps helps to achieve route summarization towards L3Out peers only, and not within the ACI fabric.

With the route summarization configured, the aggregate prefix would be advertised to external L3Out peers and more-specific prefixes would not be advertised to the L3Out peers.

To achieve summarization of routes into the ACI fabric as well as towards external L3Out peers, see Configure route control policy in VRF using the GUI.

Before you begin

For each of the following configurations, you have already created an L3 Out. For the L3 Out, you can create external routed networks, subnets, and route summarization polices.

Procedure

  1. Configure BGP route summarization using the GUI as follows:

    1. On the menu bar, choose Tenants > common
    2. In the Navigation pane, expand Networking > L3Outs.
    3. Right-click on L3Outs, then select Create L3Out.
      The Create L3Out wizard appears.
    4. In the work pane, enter the necessary information (Name, VRF, and L3 Domain), then check the check box NEXT to BGP.
    5. Click NEXT.
      The Nodes and Interfaces window appears.
    6. In the Nodes and Interfaces window, fill in the appropriate fields, then click NEXT.
      The Protocols window appears.
    7. In the Protocols window, fill in the appropriate fields, then click NEXT.
      The External EPG window appears.
    8. Enter a name in the Name field, then uncheck the Default EPG for all external networks field.
      The Subnets field appears.
    9. Click + above Route Summarization Policy.
      The Create Subnet dialog box appears.
    10. In the Specify the Subnet dialog box, you can associate a route summarization policy to the subnet as follows:

    Example:

    • Enter an IP address in the IP Address field.

    • Check the check box NEXT to Export Route Control Subnet.

    • Check the check box NEXT to External Subnets for the External EPG.

    • From the BGP Route Summarization Policy drop-down menu, select either default for an existing (default) policy or Create BGP route summarization policy to create a new policy.

    • If you selected Create BGP route summarization policy, the Create BGP Route Summarization Policy dialog box appears. Enter a name for it in the Name field, check the Control State check box for Generate AS-SET information, click SUBMIT, click OK, the click FINISH.

      Note

      The Do not advertise more specifics control state option and Address Type Control option are applicable only when a policy is applied on the VRF Route Control policy. Here, both AF Ucast and AF Mcast are enabled by default.

  2. Configure OSPF inter-area and external summarization using the GUI as follows:

    1. On the menu bar, choose Tenants > common.
    2. In the Navigation pane, expand Networking > L3Outs > External EPGs, then click on the configured external EPG.
      The overview information for that configured external EPG appears.
    3. In the work pane, click the + sign above Route Summarization Policy.
      The Create Subnet dialog box appears.
    4. In the Specify the Subnet dialog box, you can associate a route summarization policy to the subnet as follows:

    Example:

    • Enter an IP address in the IP Address field.

    • Check the check box NEXT to Export Route Control Subnet.

    • Check the check box NEXT to External Subnets for the External EPG.

    • From the OSPF Route Summarization Policy drop-down menu, choose either default for an existing (default) policy or Create OSPF route summarization policy to create a new policy.

    • If you chose Create OSPF route summarization policy, the Create OSPF Route Summarization Policy dialog box appears. Enter a name for it in the Name field, check the check box NEXT to Inter-Area Enabled, enter a value NEXT to Cost, click SUBMIT.

  3. Configure EIGRP summarization using the GUI as follows:

    1. On the menu bar, choose Tenants > common
    2. In the Navigation pane, expand Networking.> L3Outs.
    3. Right-click on L3Outs, choose Create L3Out.
      The Create L3Out dialog box appears.
    4. In the work pane, check the check box NEXT to EIGRP.
    5. Enter a name in the Name field, click NEXT.
      The External EPG Networks dialog box appears.
    6. In the work pane, click the + sign.
      The Define an External Network dialog box appears.
    7. Enter a name in the Name field, then click the + sign above Route Summarization Policy.
      The Create Subnet dialog box appears.
    8. In the Specify the Subnet dialog box, you can associate a route summarization policy to the subnet as follows:

    Example:

    • Enter an IP address in the IP Address field.

    • Check the check box NEXT to Export Route Control Subnet.

    • Check the check box NEXT to External Subnets for the External EPG.

    • Check the check box NEXT to EIGRP Route Summarization, click OK, click OK, click FINISH.

Route summarization policies are successfully configured at the L3Out External EPG level for BGP, OSPF, and EIGRP protocols. The aggregate prefixes will be advertised to external L3Out peers while more-specific prefixes will not be advertised to the L3Out peers.