Contents

• New and Changed Information
• About Broadcast Domain Assignment
• Setting the Broadcast Domain as Untagged

First Published: September 27, 2016

New and Changed Information

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The following table provides an overview of the significant changes to this guide up to this current release. The table does not provide an exhaustive list of all changes made to the guide or of the new features up to this release.

Table 1 New and Changed Information

Cisco Nexus Fabric Manager	Feature	Description
Release 1.2(1)	--	This article was created.

About Broadcast Domain Assignment

Broadcast domains within the Cisco Nexus Fabric Manager consist of a 1-to-1 mapping of VLANs to VXLAN VNI segments. When creating a broadcast domain, you may assign a VLAN or it is assigned by the Cisco Nexus Fabric Manager. The VXLAN VNI portion of the mapping is always assigned by the Cisco Nexus Fabric Manager and is a fixed offset from the VLAN ID of 20,000 by default.

The act of creating a broadcast domain within the Cisco Nexus Fabric Manager does not result initially in any configuration being created or pushed to the fabric switches. An active member perimeter interface must be added to the broadcast domain for it to become active, and for the Cisco Nexus Fabric Manager to push the configuration to the leaf switches.

In all cases, when a perimeter interface is assigned one or more broadcast domains, the perimeter interface is put into VLAN trunking mode. This is done via the switchport mode trunk CLI command that is present on the switch interface. The VLAN ID assigned to the broadcast domain is added as part of the allowed trunked VLANs via the switchport trunk allowed vlan vlan_id CLI command. By default, all VLANs associated with broadcast domains that are applied to perimeter interfaces, are added in VLAN trunking mode and are tagged VLANs.

To assign a broadcast domain to a perimeter interface so that the associated VLAN is not tagged, you must first add the interface to the broadcast domain and then set the untagged broadcast domain of the interface to the same broadcast domain. This sets the native VLAN on the interface to be the requested VLAN. However, the interface remains in a trunking configuration.

Setting the Broadcast Domain as Untagged

Procedure

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Step 1	Display the details pane of the desired perimeter interface by clicking the name of the interface in its tile. A valid perimeter interface is any interface in that is in either a host facing or border role.
Step 2	Click the BROADCAST DOMAINS tab.
Step 3	Click the settings icon drop-down menu and choose Manage membership.
Step 4	In the membership editor, click on any available broadcast domain. A summary pane appears on the right side of the window.
Step 5	Click the SET UNTAGGED button. This action adds the interface to the broadcast domain and also sets it as the chosen untagged broadcast domain. A small tag icon appears in the broadcast domain tile.
Step 6	To reverse this action, click the UNSET UNTAGGED button. Note    You must also click the (-) icon in the broadcast domain tile to fully remove the broadcast domain from the interface.

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