Chapter 9 Interfaces
USG20(W)-VPN Series User’s Guide
218
• IP address - If the DHCP client’s MAC address is in the USG’s static DHCP table, the interface
assigns the corresponding IP address. If not, the interface assigns IP addresses from a pool,
defined by the starting address of the pool and the pool size.
The USG cannot assign the first address (network address) or the last address (broadcast
address) in the subnet defined by the interface’s IP address and subnet mask. For example, in
the first entry, if the subnet mask is 255.255.255.0, the USG cannot assign 50.50.50.0 or
50.50.50.255. If the subnet mask is 255.255.0.0, the USG cannot assign 50.50.0.0 or
50.50.255.255. Otherwise, it can assign every IP address in the range, except the interface’s IP
address.
If you do not specify the starting address or the pool size, the interface the maximum range of IP
addresses allowed by the interface’s IP address and subnet mask. For example, if the interface’s
IP address is 9.9.9.1 and subnet mask is 255.255.255.0, the starting IP address in the pool is
9.9.9.2, and the pool size is 253.
• Subnet mask - The interface provides the same subnet mask you specify for the interface. See
Address Assignment on page 216
.
• Gateway - The interface provides the same gateway you specify for the interface. See
• DNS servers - The interface provides IP addresses for up to three DNS servers that provide DNS
services for DHCP clients. You can specify each IP address manually (for example, a company’s
own DNS server), or you can refer to DNS servers that other interfaces received from DHCP
servers (for example, a DNS server at an ISP). These other interfaces have to be DHCP clients.
It is not possible for an interface to be the DHCP server and a DHCP client simultaneously.
WINS
WINS (Windows Internet Naming Service) is a Windows implementation of NetBIOS Name Server
(NBNS) on Windows. It keeps track of NetBIOS computer names. It stores a mapping table of your
network’s computer names and IP addresses. The table is dynamically updated for IP addresses
assigned by DHCP. This helps reduce broadcast traffic since computers can query the server instead
of broadcasting a request for a computer name’s IP address. In this way WINS is similar to DNS,
although WINS does not use a hierarchy (unlike DNS). A network can have more than one WINS
server. Samba can also serve as a WINS server.
PPPoE/PPTP Overview
Point-to-Point Protocol over Ethernet (PPPoE, RFC 2516) and Point-to-Point Tunneling Protocol
(PPTP, RFC 2637) are usually used to connect two computers over phone lines or broadband
connections. PPPoE is often used with cable modems and DSL connections. It provides the following
advantages:
• The access and authentication method works with existing systems, including RADIUS.
• You can access one of several network services. This makes it easier for the service provider to
offer the service
Table 85
Example: Assigning IP Addresses from a Pool
START IP ADDRESS
POOL SIZE
RANGE OF ASSIGNED IP ADDRESS
50.50.50.33
5
50.50.50.33 - 50.50.50.37
75.75.75.1
200
75.75.75.1 - 75.75.75.200
99.99.1.1
1023
99.99.1.1 - 99.99.4.255
120.120.120.100
100
120.120.120.100 - 120.120.120.199
Summary of Contents for ZyWall USG20-VPN
Page 17: ...17 PART I User s Guide ...
Page 18: ...18 ...
Page 99: ...99 PART II Technical Reference ...
Page 100: ...100 ...
