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 Microsoft NLB in IGMP mode using the GUI

Updated: April 17, 2026

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Configures Microsoft NLB to flood traffic on specific ports within the bridge domain using IGMP mode. This procedure enables the integration of Microsoft NLB clusters with the fabric by defining subnet and multicast group settings.

Before you begin

Have the following information available before proceeding with these procedures:

  • Microsoft NLB cluster VIP

This task configures Microsoft NLB to flood only on certain ports in the bridge domain.

Procedure

1.

In the Navigation pane, choose Tenant > tenant_name > Application Profiles > application_profile_name > Application EPGs > application_EPG_name > Subnets .

2.

Right-click Subnets and select Create EPG Subnet .

3.

In the Create EPG Subnet dialog box, fill in the following fields:

  1. In the Default Gateway IP field, enter the Microsoft NLB cluster VIP.

    For example, 192.0.2.1/32 .

  2. In the Scope area, for shared services, check Shared between VRFs .

    Uncheck Private to VRF , if it is selected.

  3. Under Subnet Control , check the No Default SVI Gateway check box.

  4. In the Type Behind Subnet area, click EpNlb .

    The Mode field appears.

  5. From the Mode drop-down list, choose NLB in IGMP mode .

    The Group Id field appears.

  6. In the Group Id field, enter the Microsoft NLB multicast group address.

    For the Microsoft NLB multicast group address, the last two octets of the address correspond to the last two octets of the instance cluster IP address. For example, if the instance cluster IP address is 10.20.30.40 , then the Microsoft NLB multicast group address that you would enter into this field might be 239.255.30.40 .

4.

Click Submit .

Traffic to the Microsoft NLB cluster VIP will be flooded to the outgoing interface list that is either configured statically from the APIC or dynamically based on IGMP joins from the NLB cluster.
5.

Determine if you want to have a static join or a dynamic join.

You can have a combination of static joins and dynamic joins, where some ports can have a static join and other ports can have a dynamic join.

  • Dynamic Join: In the dynamic join, the join is sent by the Microsoft NLB cluster on the respective ports, then the switch dynamically comes up with that outgoing interface list.

  • Static Join: In the static join, traffic to the Microsoft NLB cluster VIP will go to the ports that you configure in the following steps.

    If you want to have a static join:

    1. Copy the Microsoft NLB multicast group address that you entered in the Group Id field in 3.f .

    2. In the Navigation pane, choose Tenant > tenant_name > Application Profiles > application_profile_name > Application EPGs > application_EPG_name > Static Ports > static_port .

      Choose the static port that you want to configure Microsoft NLB to flood onto in the bridge domain.

    3. On the Static Path page for this port, fill in the following field:

      • In the IGMP Snoop Static Group area, click + (Create), then paste the group address that you copied from 3.f into the Group Address field.

      • Click Update underneath the Group Address field.

    4. In the Static Path page, click Submit .

IGMP snooping is enabled by default on the bridge domain because the IGMP snooping policy default that is associated with the bridge domain has Enabled as the administrative state of the policy. For more information, see Configure an IGMP snooping policy using the GUI .