Layer 2 interface vs Virtual Wire

[James.Jiang]

Virtual wire mode, the interfaces assigned to virtual wire are transparent mode.

Layer 2 interfaces: interfaces can assigned to different zone.

[James.Jiang]

Virtual Wire Configuration
Each virtual wire interface (ethernet 1/1 and ethernet 1/2) must be connected to a security zone and a virtual wire. To configure these settings, select the Config tab and complete the following tasks:
In the Virtual wire drop-down click New Virtual Wire, define a Name and assign the two data interfaces (ethernet 1/1 and ethernet 1/2) to it, and then click OK.When configuring ethernet 1/2, select this virtual wire. Select New Zone from the Security Zone drop-down, define a Name for new zone, for example client, and then click OK.
Layer 2 Configuration
For each Layer 2 interface, you require a security zone. Select the Config tab and complete the following tasks:
Select New Zone from the Security Zone drop-down, define a Name for new zone, for example client, and then click OK.
Repeat steps 2 and 3 above for the other interface.
Click Commit to save changes to the firewall.

[RandyA]

Switching is required when using a layer 2 interface, no switching is required when using a virtual wire. Packets are sent regardless when using the v-wire. A v-wire is technically a bridge.