Subnet And Mask - Huawei Quidway S5600 Series Operation Manual

Operation Manual – IP Address and Performance Confiugration
Quidway S5600 Series Ethernet Switches-Release 1510
Network
type
E
Others

1.1.2 Subnet and Mask

The traditional IP address classification method wastes IP addresses greatly. In
order to make full use of the available IP addresses, the concepts of mask and
subnet were introduced.
A mask is a 32-bit number corresponding to an IP address. The number consists of
1s and 0s. An mask is defined as follows: the bits of the network number and
subnet number are set to 1, and the bits of the host number are set to 0. The mask
divides the IP address into two parts: subnet address and host address. In an IP
address, the part corresponding to the "1" bits in the mask is the subnet address,
and the part corresponding to the remaining "0" bits in the mask is the host
address. If there is no subnet division, the subnet mask uses the default value and
the length of 1s in the mask is equal to the net-id length. Therefore, for IP
addresses of classes A, B and C, the default values of the corresponding subnet
masks are 255.0.0.0, 255.255.0.0 and 255.255.255.0 respectively.
The mask can be used to divide a Class A network containing more than
16,000,000 hosts or a Class B network containing more than 60,000 hosts into
multiple small networks. Each small network is called a subnet. For example, for
the Class B network address 138.38.0.0, the mask 255.255.224.0 can be used to
divide the network into eight subnets: 138.38.0.0, 138.38.32.0, 138.38.64.0,
138.38.96.0, 138.38.128.0, 138.38.160.0, 138.38.192.0 and 138.38.224.0 (see
Figure 1-2). Each subnet can contain more than 8000 hosts.
IP network
Address range
240.0.0.0 to
255.255.255.25 None
4
255.255.255.25 255.255.255
5 .255
Huawei Technologies Proprietary
1-3
Chapter 1 IP Address Configuration
range
These IP
reserved for future use.
255.255.255.255 is used as a
LAN broadcast address.
Description
addresses are