Security Labs PTZ IP Camera, Руководство пользователя

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reserved for the host ID.
Class Value of First Octet Network ID Host ID Number of Hosts
A 1-126 First octet Last three octets 16,387,064
B 128-191 First two octets Last two octets 64,516
C 192-223 First three octets Last octet 254
Any value between 0 and 255 is valid as a host ID octet except for those values
the InterNIC reserves for other purposes
Value Purpose
0, 255 Subnet masking
127 Loopback testing and interprocess communication on local devices
224-254 IGMP multicast and other special protocols.
Subnetting and Subnet Masks
Subnetting divides a network address into sub-network addresses to
accommodate more than on physical network on a logical network.
For example:
A Class B company has 100 LANs (Local Area Networks) with 100 to 200 nodes
on each LAN. To classify the nodes by its LANs on one main network, this
company segments the network address into 100 sub-network addresses.
If the
Class B network address is 150.1.x.x, the address can be segmented further
from 150.1.1.x through 150.1.100.x
A subnet mask is a 32-bit value that distinguishes the network ID from the host
ID for different sub-networks on the same logical network.
Like IP addresses,
subnet masks consist of four octets in dotted decimal notation. You can use
subnet masks to route and filter the transmission of IP packets among your
sub-networks. The value “255” is assigned to octets that belong to the network
ID, and the value “0” is assigned to octets that belong to the host ID.
For the example above, if you want all the devices on the sub-networks to
receive each other’s IP packets, set the subnet mask to 255.255.0.0.
If you
want the devices on a single sub-network only to receive IP packets from other
devices on its own sub-network, set the subnet mask to 255.255.255.0 for the
devices on the sub-network.
Subnet Mask Routing and Filtering
0.0.0.0 IP packets are transmitted to all devices.
255.0.0.0 IP packets are only transmitted to devices that are IP that’s first octet
matches the sender’s IP address’s first octet.
255.255.0.0 IP packets are only transmitted to devices that are IP that’s first two
octets match the sender’s IP address’s first two octets.
255.255.255.0 IP packets are only transmitted to devices that are IP that’s first three
octets match the sender’s IP address’s first three octets.
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