User`s guide

Signamax 065-7931 16-Port 10/100/1000BaseT/TX WebSmart Switch

Class D and E:

Class D is a class with the first 4 MSB (Most Significant Bits) set to 1-1-1-0

and is used for IP Multicast. See also RFC 1112. Class E is a class with the 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 a Private IP address, and list them 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:

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 ease the management of an IP network.

For a class B network, using the example 128.1.2.3, that network may have a

subnet mask 255.255.0.0 as the default, in which the first two bytes will be all 1s.

This means more than 60 thousand nodes in flat IP addresses will be at the same

network. Such a network is too large to practically manage. If the network is divided

into a smaller network by extending its network prefix from 16 bits to, say 24 bits,

that uses its third byte to subnet this class B network. That network now has a

subnet mask of 255.255.255.0, in which each bit of the first three bytes is 1. It is

now clear that the first two bytes are used to identify the class B network, the third

byte is used to identify the subnet within this class B network, and the last byte is

then the host number.

Not all IP addresses are available in the sub-netted network. Two special

addresses are reserved. They are the addresses with all zeros and all ones as the

host number. For example, for an IP address of 128.1.2.128, what will the reserved

IP addresses look like? All 0s mean the network itself, and all 1s mean IP broadcast.

10000000.00000001.00000010.1 0000000

128.1.2.128/25

25 bits

1 0000000

1 1111111

All 0s = 128.1.2.128

All 1s= 128.1.2.255

Subne

etwor