SignaMax 065-7940C-WS, Руководство пользователя

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Signamax
™
065-7840C-WS 24-Port 10/100/1000BaseT/TX WebSmart Switch
Publication date: June, 2011
Revision 1.0
16
Class B:
IP address range between 128.0.0.0 and 191.255.255.255. Each class B
network has a 16-bit network prefix followed 16-bit host address. There are 16,384
(2^14)/16 networks able to be defined with a maximum of 65534 (2^16 –2) hosts
per network.
10
Class C:
IP address range between 192.0.0.0 and 223.255.255.255. Each class C
network has a 24-bit network prefix followed 8-bit host address. There are
2,097,152 (2^21)/24 networks able to be defined with a maximum of 254 (2^8 –2)
hosts per network.
110
Class D and E:
Class D is a class with first 4 MSB (Most significance bit) set to 1-1-1-0 and
is used for IP Multicast. See also RFC 1112. Class E is a class with first 4 MSB set
to 1-1-1-1 and is used for IP broadcast.
According to IANA (Internet Assigned Numbers Authority), there are three
specific IP address blocks reserved and able to be used for extending internal
network. We call it Private IP address and list below:
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
Please refer to RFC 1597 and RFC 1466 for more information.
Subnet mask:
The Subnet Mask means the sub-division of a class-based network or a
CIDR block. The subnet is used to determine how to split an IP address to the
network prefix and the host address on a bitwise basis. It is designed to utilize IP
addresses more efficiently and make it easier to manage an IP network.
For a class B network, 128.1.2.3, it may have a subnet mask 255.255.0.0 in
default, in which the first two bytes are all 1s. This means more than 60 thousand
nodes in flat IP addresses will be on the same network. It’s too large to manage
practically. Now if we divide it into a smaller network by extending the network prefix
from 16 bits to, say 24 bits, which uses its third byte to subdivide this class B
network into subnets. Now it has a subnet mask of 255.255.255.0, in which each bit
of the first three bytes is 1. It’s now clear that the first two bytes is used to identify
the class B network, the third byte is used to identify the subnet within this class B
Bit # 01 2 15 16 31
Network address Host address
Bit # 0 1 2 3 23 24 31
Network address Host address