What You Need To Know - ZyXEL Communications ZyWall USG20-VPN User Manual

9.1.2 What You Need to Know

Interface Characteristics
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.
Types of Interfaces
You can create several types of interfaces in the USG.
• Setting interfaces to the same port role forms a port group. Port groups creates a hardware
connection between physical ports at the layer-2 (data link, MAC address) level. Port groups are
created when you uUse the Interface > Port Roles or Interface > Port Groups screen to set
multiple physical ports to be part of the same interface.
• Ethernet interfaces are the foundation for defining other interfaces and network policies. RIP
and OSPF are also configured in these interfaces.
• Tunnel interfaces send IPv4 or IPv6 packets from one network to a specific network through
the Internet or a public network.
• VLAN interfaces receive and send tagged frames. The USG 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 USG. 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 mobile broadband WAN connections via a connected mobile
broadband device.
• Virtual interfaces provide additional routing information in the USG. There are three types:
virtual Ethernet interfaces, virtual VLAN interfaces, and virtual bridge interfaces.
• Trunk interfaces manage load balancing between interfaces.
Port groups and trunks have a lot of characteristics that are specific to each type of interface. The
other types of interfaces--Ethernet, PPP, cellular, VLAN, bridge, and virtual--have a lot of similar
Chapter 9 Interfaces
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