3Com OfficeConnect 3CR856-95, User Manual

Page: 68 / 96

68
Type Two
In larger networks, where there are more devices, the IP address
of ‘192.168.100.8’ is, again, split into two parts but is structured
differently:
■
Part one (‘192.168’) identifies the network on which the
device resides.
■
Part two (‘.100.8’) identifies the device within the network.
This type of IP Address operates on a subnet mask of
‘255.255.0.0’.
See Table 4 for an example about how a network (only four PCs
represented) and a Cable/DSL Secure Gateway might be
configured.
How does a Device Obtain an IP Address and
Subnet Mask?
There are three different ways to obtain an IP address and the
subnet mask. These are:
■
Dynamic Host Configuration Protocol (DHCP) Addressing
■
Static Addressing
■
Automatic Addressing (Auto-IP Addressing)
DHCP Addressing
The Cable/DSL Secure Gateway contains a DHCP server, which
allows computers on your network to obtain an IP address and
subnet mask automatically. DHCP assigns a temporary IP address
and subnet mask which gets reallocated once you disconnect
from the network.
DHCP will work on any client Operating System such as
Windows
®
95, Windows 98 or Windows NT 4.0. Also, using
DHCP means that the same IP address and subnet mask will
never be duplicated for devices on the network. DHCP is
particularly useful for networks with large numbers of users on
them.
Static Addressing
You must enter an IP Address and the subnet mask manually on
every device. Using a static IP and subnet mask means the
address is permanently fixed.
Auto-IP Addressing
Network devices use automatic IP addressing if they are
configured to acquire an address using DHCP but are unable to
Cable/DSL
Secure Gateway 192.168.100.72 255.255.255.0
Table 4 IP Addressing and Subnet Masking in a Large Network
Device IP Address Subnet Mask
PC 1 192.168.100.8 255.255.0.0
PC 2 192.168.201.30 255.255.0.0
PC 3 192.168.113.155 255.255.0.0
PC 4 192.168.002.230 255.255.0.0
Cable/DSL Secure
Gateway 192.168.002.72 255.255.0.0
Table 3 IP Addressing and Subnet Masking in a Small Network
Device IP Address Subnet Mask
dua08569-5aaa01.book Page 68 Wednesday, March 13, 2002 10:39 AM