Sub-Interface Configuration

[Sanjay_Ramaiah]

Hi All,

Please help. I never configured Sub-Interface in PA. There is a new requirement to configure a sub-interface under already configured interface. So my doubt is how this Sub-interface if we already configured the physical interface with the IP address? What is the use of Sub-interface is it similar to the VLAN interfaces in Checkpoint and ASA? In what situations we use Sub-interfaces? What is the use of VLAN if sub interfaces act as VLAN interfaces?

Also can we configure 2 interfaces with the IP addresses in the same subnet? Like 1.1.1.1/29 on one interface and 1.1.1.2/29 on other interface and attach different VRs to both those interfaces?

Regards,

Sanjay S

[JayGolf · Accepted solution]

Hi @Sanjay_Ramaiah ,

Think of sub-interfaces as a way to divide one physical network connection into multiple virtual connections. It's like having several mini-networks within a single network connection.

For example, let's say you have three VLANs: VLAN 10, VLAN 20, and VLAN 30. Instead of needing three separate physical ports on the firewall, you can create three sub-interfaces on a single physical port. Each sub-interface is associated with one VLAN.

By doing this, you can treat each sub-interface as if it were a separate network port. You can apply different security rules, policies, and routing configurations to each sub-interface. It helps in isolating traffic between different VLANs or subnets and controlling how they communicate with each other.