How do you create a VLAN interface VLAN10 on top of interface ether2 and attach it to a bridge?

How do you create a VLAN interface VLAN10 on top of interface ether2 and attach it to a bridge?

• A. /interface vlan add name=vlan10 vlan-id=10 interface=ether2
• B. /interface bridge port add bridge=bridge1 interface=vlan10
• C. /interface vlan add name=vlan10 vlan-id=10 interface=bridge1
• D. /interface vlan add name=vlan10 vlan-id=10 interface=ether2; /interface bridge port add bridge=bridge1 interface=vlan10

Answer: (D)

In RouterOS, VLANs are virtual interfaces created on top of a physical port, and to have that VLAN participate in a bridge you must add the VLAN interface as a bridge port. The correct sequence creates the VLAN on the actual hardware path first, then attaches that VLAN interface to the bridge so traffic tagged for that VLAN can be bridged with other bridge ports. First, you create the VLAN on top of the physical interface ether2: interface vlan add name=vlan10 vlan-id=10 interface=ether2 Then, you attach that VLAN interface to the bridge so it becomes part of the bridge’s forwarding domain: interface bridge port add bridge=bridge1 interface=vlan10 This two-step process is necessary because a VLAN needs to exist as a separate interface layered over a physical port, and only then can it be treated as a bridge port. Creating the VLAN alone doesn’t place it into the bridge, and attaching a VLAN to a bridge before the VLAN exists (or attaching the bridge to the VLAN interface in place of the physical path) wouldn’t correctly establish the network path for tagged traffic.

In RouterOS, VLANs are virtual interfaces created on top of a physical port, and to have that VLAN participate in a bridge you must add the VLAN interface as a bridge port. The correct sequence creates the VLAN on the actual hardware path first, then attaches that VLAN interface to the bridge so traffic tagged for that VLAN can be bridged with other bridge ports.

First, you create the VLAN on top of the physical interface ether2:

interface vlan add name=vlan10 vlan-id=10 interface=ether2

Then, you attach that VLAN interface to the bridge so it becomes part of the bridge’s forwarding domain:

interface bridge port add bridge=bridge1 interface=vlan10

This two-step process is necessary because a VLAN needs to exist as a separate interface layered over a physical port, and only then can it be treated as a bridge port. Creating the VLAN alone doesn’t place it into the bridge, and attaching a VLAN to a bridge before the VLAN exists (or attaching the bridge to the VLAN interface in place of the physical path) wouldn’t correctly establish the network path for tagged traffic.