Special Case Ip Addresses; Subnetting And Masking - H3C S3100-52P Operation Manual

Operation Manual – IP Address and Performance
H3C S3100-52P Ethernet Switch
Table 1-1 IP address classes and ranges
Class
A
B
C
D
E

1.1.2 Special Case IP Addresses

The following IP addresses are for special use, and they cannot be used as host IP
addresses:
IP address with an all-zeros net ID: Identifies a host on the local network. For
example, IP address 0.0.0.16 indicates the host with a host ID of 16 on the local
network.
IP address with an all-zeros host ID: Identifies a network.
IP address with an all-ones host ID: Identifies a directed broadcast address. For
example, a packet with the destination address of 192.168.1.255 will be
broadcasted to all the hosts on the network 192.168.1.0.

1.1.3 Subnetting and Masking

Subnetting was developed to address the risk of IP address exhaustion resulting from
fast expansion of the Internet. The idea is to break a network down into smaller
networks called subnets by using some bits of the host ID to create a subnet ID. To
identify the boundary between the host ID and the combination of net ID and subnet ID,
masking is used.
Each subnet mask comprises 32 bits related to the corresponding bits in an IP address.
In a subnet mask, the part containing consecutive ones identifies the combination of net
ID and subnet ID whereas the part containing consecutive zeros identifies the host ID.
Figure 1-2
Address range
0.0.0.0 to 127.255.255.255
128.0.0.0 to 191.255.255.255
192.0.0.0 to 223.255.255.255
224.0.0.0 to 239.255.255.255
240.0.0.0 to 255.255.255.255
shows how a Class B network is subnetted.
Chapter 1 IP Addressing Configuration
Address 0.0.0.0 means this host no
this network. This address is used by a
host at bootstrap when it does not
know its IP address. 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.
––
––
Multicast address.
Reserved for future use except for the
broadcast address 255.255.255.255.
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Description