how to edit the layers in omnet++ or inet?

I want to create or edit the nodes in inet or omnet++.

Instead of having seven layers for example, I want a host with three layers (phys, mac and app)

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There are several approaches, from the most complex to the simplest:

• Build your own node from scratch (you can use EthernetHost as an example)
• Build your own host module but extend LinkLayerNodeBase. That will inherit only up to the link layer.
• Just use StandardHost and disable the layers you don't need (i.e. set the parameter hasIpv4, hasUdp and hasTcp to false)
• Just use StandardHost and ignore the unused layers. If an application opens a raw socket on layer 2 (like EthernetApp and all its descendant) then packets sent by the app will anyway directly sent to the linklayer and routed around the transport and network layers).