H3C Technologies H3C S10500 Series Switches - Manual (Page 34)

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IP addressing configuration
NOTE:
The term interface in this document refers to Layer 3 interfaces, including VLAN interfaces and route-mode
(or Layer 3) Ethernet ports. You can set an Ethernet port to operate in route mode by using the port
link-mode route command (see
Layer 2—LAN Switching Configuration Guide).
IP addressing overview
IP address classes
IP addressing uses a 32-bit address to identify each host on a network. To make addresses easier to read,
they are written in dotted decimal notation, each address being four octets in length. For example,
address 00001000000000010000000100000001 in binary is written as 10.1.1.1.
Each IP address breaks down into two parts:
• Net ID: Identifies a network. The first several bits of a net ID, known as the class field or class bits,
identify the class of the IP address.
• Host ID: Identifies a host on a network.
IP addresses are divided into five classes, shown in Figure 13 . The shaded areas represent the address
class. The first three classes are widely used.
Figure 13 IP address classes
0 Net ID Host ID
1 Net ID Host ID 0
1 Net ID Host ID 0 1
1 Multicast address 0 1 1
1 Reserved 1 1 1
Class A
Class B
Class C
Class D
Class E
0 7 15 23 31
0
Table 1 IP address classes and ranges
Class Address range Remarks
A
0.0.0.0 to
127.255.255.255
The IP address 0.0.0.0 is used by a host at startup for temporary
communication. This address is never a valid destination address.
Addresses starting with 127 are reserved for loopback test.
Packets destined to these addresses are processed locally as input
packets rather than sent to the link.
B
128.0.0.0 to
191.255.255.255
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