R3166-R3206-HP High-End Firewalls Network Management Configuration Guide-6PW101

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Subnetting increases the number of addresses that cannot be assigned to hosts. Therefore, using subnets
means accommodating somewhat fewer hosts
For example, a Class B network without subnetting can accommodate 1022 more hosts than the same
network subnetted into 512 subnets.
• Without subnetting: 65,534 hosts (2
16
– 2). (The two deducted addresses are the broadcast
address, which has an all-one host ID, and the network address, which has an all-zero host ID.)
• With subnetting: Using the first 9 bits of the host-id for subnetting provides 512 (2
9
) subnets.
However, only 7 bits remain available for the host ID. This allows 126 (2
7
– 2) hosts in each subnet,
a total of 64,512 hosts (512 × 126).
Configuring IP addresses
Assigning an IP address for an interface
An interface must have an IP address to communicate with other hosts. You can either manually assign
an IP address to an interface, or configure the interface to obtain an IP address through DHCP. If you
change the way an interface obtains an IP address, the new IP address will overwrite the previous one.
NOTE:
This chapter only covers how to assign an IP address manually. For more information about IP address
allocation through DHCP, see the chapter “DHCP overview.”
You may assign an interface multiple IP addresses, one primary and multiple secondaries.
Generally, you only need to assign the primary address to an interface. In some cases, you must assign
secondary IP addresses to the interface. For example, if the interface connects to two subnets, to enable
the firewall to communicate with all hosts on the LAN, you need to assign a primary IP address and a
secondary IP address to the interface.
Follow these steps to assign an IP address to an interface:
To do… Use the command…
Remarks
Enter system view system-view ––
Enter interface view
interface interface-type
interface-number
––
Assign an IP address to the
interface
ip address ip-address { mask-length
| mask } [ sub ]
Required
No IP address is assigned by
default.
NOTE:
• An interface can have only one primary IP address. A newly confi
g
ured primary IP address overwrites
the previous one.
• The primary and secondary IP addresses you assign to the interface can be located on the same
network segment, but different interfaces on your firewall must reside on different network segments.