Beginning with ONTAP 9.8, broadcast domains are automatically created during the cluster create or join operation. Beginning with ONTAP 9.12.0, in addition to the automatically created broadcast domains, you can manually add a broadcast domain in ONTAP System Manager.

Before you begin

The ports you plan to add to the broadcast domain must not belong to another broadcast domain. If the ports you want to use belong to another broadcast domain, but are unused, remove those ports from the original broadcast domain.

About this task

All broadcast domain names must be unique within an IPspace.
The ports added to a broadcast domain can be physical network ports, VLANs, or link aggregation groups/interface groups (LAGs/ifgrps).
If the ports you want to use belong to another broadcast domain, but are unused, remove them from existing broadcast domain before adding them to the new one.
The maximum transmission unit (MTU) of the ports added to a broadcast domain are updated to the MTU value set in the broadcast domain.
The MTU value must match all the devices connected to that layer 2 network except for the e0M port handling management traffic.
If you do not specify an IPspace name, the broadcast domain is created in the "Default" IPspace.

To make system configuration easier, a failover group of the same name is created automatically that contains the same ports.

ONTAP System Manager

Steps

Select Network > Overview > Broadcast domain.
Click
Name the broadcast domain.
Set the MTU.
Select the IPspace.
Save the broadcast domain.

You can edit or delete a broadcast domain after it has been added.

CLI

In ONTAP 9.7, you can manually create a broadcast domain.

If you are using ONTAP 9.8 and later, broadcast domains are created automatically based on layer-2 reachability. For more information, see Repair port reachability.

Steps

View the ports that are not currently assigned to a broadcast domain:

network port show

If the display is large, use the network port show -broadcast-domain command to view only unassigned ports.
Create a broadcast domain:

network port broadcast-domain create -broadcast-domain broadcast_domain_name -mtu mtu_value [-ipspace ipspace_name] [-ports ports_list]
1. broadcast_domain_name is the name of the broadcast domain you want to create.
2. mtu_value is the MTU size for IP packets; 1500 and 9000 are typical values.
  
  This value is applied to all ports that are added to this broadcast domain.
3. ipspace_name is the name of the IPspace to which this broadcast domain will be added.
  
  The "Default" IPspace is used unless you specify a value for this parameter.
4. ports_list is the list of ports that will be added to the broadcast domain.
  
  The ports are added in the format node_name:port_number, for example, node1:e0c.
Verify that the broadcast domain was created as desired:

network port show -instance -broadcast-domain new_domain

Example

The following command creates broadcast domain bcast1 in the Default IPspace, sets the MTU to 1500, and adds four ports:

network port broadcast-domain create -broadcast-domain bcast1 -mtu 1500 -ports cluster1-01:e0e,cluster1-01:e0f,cluster1-02:e0e,cluster1-02:e0f

After you finish

You can define the pool of IP addresses that will be available in the broadcast domain by creating a subnet, or you can assign SVMs and interfaces to the IPspace at this time. For more information, see Cluster and SVM peering.

If you need to change the name of an existing broadcast domain, use the network port broadcast-domain rename command.