PCNSE · Question #94
A network design calls for a "router on a stick" implementation with a PA-5060 performing inter- VLAN routing All VLAN-tagged traffic will be forwarded to the PA-5060 through a single dot1q trunk inte
The correct answer is D. Layer 3 subinterface type with specified tag. For a 'router on a stick' implementation on a Palo Alto Networks firewall, a Layer 3 subinterface with a specified VLAN tag is the required interface type to perform inter-VLAN routing.
Question
A network design calls for a "router on a stick" implementation with a PA-5060 performing inter- VLAN routing All VLAN-tagged traffic will be forwarded to the PA-5060 through a single dot1q trunk interface Which interface type and configuration setting will support this design?
Options
- ATrunk interface type with specified tag
- BLayer 3 interface type with specified tag
- CLayer 2 interface type with a VLAN assigned
- DLayer 3 subinterface type with specified tag
How the community answered
(20 responses)- A10% (2)
- C5% (1)
- D85% (17)
Why each option
For a 'router on a stick' implementation on a Palo Alto Networks firewall, a Layer 3 subinterface with a specified VLAN tag is the required interface type to perform inter-VLAN routing.
A 'Trunk interface type' is not a standard, configurable interface type in Palo Alto Networks PAN-OS; the functionality of carrying multiple VLANs on a single physical link is achieved through subinterfaces.
A standard Layer 3 interface handles untagged traffic or a single subnet, and it cannot process multiple tagged VLANs over one physical interface without being configured as subinterfaces.
A Layer 2 interface operates at the data link layer and forwards frames within a VLAN; it does not perform inter-VLAN routing, which is a Layer 3 function.
A Layer 3 subinterface, configured with a specific VLAN tag (dot1q tag), allows a single physical interface to process traffic for multiple VLANs, effectively serving as the default gateway for each VLAN and enabling routing between them.
Concept tested: Inter-VLAN routing with subinterfaces (router on a stick)
Source: https://docs.paloaltonetworks.com/pan-os/10-2/pan-os-admin/networking/configure-interfaces/configure-a-layer-3-interface/configure-a-layer-3-subinterface
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