ZyXEL Communications 1000 User Manual

Chapter 13 Interfaces

ZyWALL USG 1000 User’s Guide

Interfaces generally have the following characteristics (although not all 
characteristics apply to each type of interface).

• An interface is a logical entity through which (layer-3) packets pass.
• An interface is bound to a physical port or another interface.
• Many interfaces can share the same physical port.
• An interface belongs to at most one zone.
• Many interfaces can belong to the same zone.
• Layer-3 virtualization (IP alias, for example) is a kind of interface.

You can create several types of interfaces in the ZyWALL.

• Port groups create a hardware connection between physical ports at the layer-

2 (data link, MAC address) level.

• Ethernet interfaces are the foundation for defining other interfaces and 

network policies. RIP and OSPF are also configured in these interfaces.

• VLAN interfaces receive and send tagged frames. The ZyWALL automatically 

adds or removes the tags as needed. Each VLAN can only be associated with 

one Ethernet interface.

• Bridge interfaces create a software connection between Ethernet or VLAN 

interfaces at the layer-2 (data link, MAC address) level. Unlike port groups, 

bridge interfaces can take advantage of some security features in the ZyWALL. 

You can also assign an IP address and subnet mask to the bridge.

• PPP interfaces support Point-to-Point Protocols (PPP). ISP accounts are 

required for PPPoE/PPTP interfaces.

• Cellular interfaces are for 3G WAN connections via a connected 3G device.
• Virtual interfaces provide additional routing information in the ZyWALL. There 

are three types: virtual Ethernet interfaces, virtual VLAN interfaces, and 

virtual bridge interfaces.

• The auxiliary interface, along with an external modem, provides an interface 

the ZyWALL can use to dial out. This interface can be used as a backup WAN 

interface, for example. The auxiliary interface controls the AUX port.

• Trunks manage load balancing between interfaces.

Port groups, trunks, and the auxiliary interface have a lot of characteristics that 
are specific to each type of interface. See 

 for details. The other types of 

interfaces--Ethernet, PPP, cellular, VLAN, bridge, and virtual--have a lot of similar