Chapter 10 Interfaces
ZyWALL USG Series User’s Guide
402
Figure 281
Example: Entry in the Routing Table Derived from Interfaces
For example, if the Zyxel Device gets a packet with a destination address of 100.100.25.25, it routes the
packet to interface lan1. If the Zyxel Device gets a packet with a destination address of 200.200.200.200,
it routes the packet to interface wan1.
In most interfaces, you can enter the IP address and subnet mask manually. In PPPoE/PPTP/L2TP
interfaces, however, the subnet mask is always 255.255.255.255 because it is a point-to-point interface.
For these interfaces, you can only enter the IP address.
In many interfaces, you can also let the IP address and subnet mask be assigned by an external DHCP
server on the network. In this case, the interface is a DHCP client. Virtual interfaces, however, cannot be
DHCP clients. You have to assign the IP address and subnet mask manually.
In general, the IP address and subnet mask of each interface should not overlap, though it is possible for
this to happen with DHCP clients.
In the example above, if the Zyxel Device gets a packet with a destination address of 5.5.5.5, it might
not find any entries in the routing table. In this case, the packet is dropped. However, if there is a default
router to which the Zyxel Device should send this packet, you can specify it as a gateway in one of the
interfaces. For example, if there is a default router at 200.200.200.100, you can create a gateway at
200.200.200.100 on ge2. In this case, the Zyxel Device creates the following entry in the routing table.
The gateway is an optional setting for each interface. If there is more than one gateway, the Zyxel
Device uses the gateway with the lowest metric, or cost. If two or more gateways have the same metric,
the Zyxel Device uses the one that was set up first (the first entry in the routing table). In PPPoE/PPTP/L2TP
interfaces, the other computer is the gateway for the interface by default. In this case, you should
specify the metric.
If the interface gets its IP address and subnet mask from a DHCP server, the DHCP server also specifies
the gateway, if any.
Interface Parameters
The Zyxel Device restricts the amount of traffic into and out of the Zyxel Device through each interface.
Table 134 Example: Routing Table Entries for Interfaces
IP ADDRESS(ES)
DESTINATION
100.100.1.1/16
lan1
200.200.200.1/24
wan1
Table 135 Example: Routing Table Entry for a Gateway
IP ADDRESS(ES)
DESTINATION
0.0.0.0/0
200.200.200.100
lan1
wan1
Summary of Contents for USG110
Page 27: ...27 PART I User s Guide ...
Page 195: ...195 PART II Technical Reference ...
Page 309: ...Chapter 10 Interfaces ZyWALL USG Series User s Guide 309 ...
Page 313: ...Chapter 10 Interfaces ZyWALL USG Series User s Guide 313 ...
Page 358: ...Chapter 10 Interfaces ZyWALL USG Series User s Guide 358 ...
Page 373: ...Chapter 10 Interfaces ZyWALL USG Series User s Guide 373 ...