Zte ZXR10 5900 Series User Manual page 62

ZXR10 5900/5200 Series User Manual (Basic Configuration Volume)
Class
Characteristic
Class D 1110
Class E 1111
48 Confidential and Proprietary Information of ZTE CORPORATION
Network Bit
Prefix
Bit
Multicast Address
Reserved
Some Class A, B and C addresses are reserved for private net-
works. It is recommended that the internal network should use
the private network address. These addresses refer to:
� Class A:10.0.0.0~10.255.255.255
�
Class B:172.16.0.0~172.31.255.255
� Class C:192.168.0.0~192.168.255.255
This address classification method is to facilitate routing protocol
designing. From this method it can be known the network type just
by the prefix characteristic bit of the IP address. This method,
however, cannot make the best of the address space. With the
dramatic expansion of Internet, problem of address shortage be-
comes increasingly serious.
To make most of IP addresses, network can be divided into multiple
subnets. Borrow some bits from the highest bit of the host bit as
the subnet bit. Remaining part of the host bit still serves as the
host bit. Thus, the structure of an IP address consists of three
parts: Network bits, subnet bits and host bits.
The network bits and subnet bits are used to uniquely identify a
network. Use the subnet mask to find which part in the IP address
indicates network bits and subnet bits and which part stands for
host bits. The part with subnet mask of "1" corresponds to the
network bits and subnet bits of the IP address, while the part with
subnet mask of "0" corresponds to host bits.
The division of the subnet greatly improves the utilization of IP
address, and alleviates the problem of IP address shortage.
Regulations on IP addresses:
1. 0.0.0.0 is used when a host without an IP address is started.
RARP, BOOTP and DHCP are used to obtain the IP address. The
address serves as the default route in the routing table.
2. 255.255.255.255 is a destination address used for broadcast
and cannot serve as a source address.
3. 127.X.X.X is called the loop-back address.
4. Only an IP address with host bits being all "0" indicate the
network itself. An IP address with host bits being all "1" serves
as the broadcast address of the network.
5. For a legal host IP address, the network part or the host part
should not be all "0" or all "1".
Host Bit Range
224.0.0.0~
239.255.255.255
240.0.0.0~
255.255.255.255