LEGRAND Omizzy, Руководство пользователя

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What is a computer network ?
A computer network is a set of computers linked
together via physical lines, and exchanging
information in the form of binary data.
IP address:
In an IP (Internet Protocol) network, every device has
a unique IP address.
This address is used to formally identify and locate
the device.
It is expressed in the form of four numbers from 0 to
255 (for example: 192.168.1.12).
An IP address is unique within one network: no
devices (computers, servers, cameras, etc) on
the network may have the same IP address, as this
would generate conflicts which could block
communication.
An IP address allocated to a device which
is connected directly to the Internet (public network)
is distinguished from that of a device in a LAN
(private network) which is not connected to the
Internet.
Only the following ranges of addresses can be used
for private networks:
- from 10.0.0.0 to 10.255.255.255
- from 172.16.0.0 to 172.31.255.255
- from 192.168.0.0 to 192.168.255.255
Addresses ending in 0 or 255 must not be used.
Network class and subnetwork mask:
IP addresses are divided into classes which represent
the extent of a network.
The class is given by the value of the subnetwork
mask.
Class A: 255.0.0.0
Class B: 255.255.0.0
Class C: 255.255.255.0
A “0” in a field indicates that the device can
communicate with all those which have the same
root.
Eg: A device which has the following address:
- IP address: 192.168.1.12
- Subnetwork mask: 255.255.255.0
can communicate with devices whose IP address
is between 192.168.1.1 and 192.168.1.254 (this
is a class C network).
Why does Omizzy™ have two IP addresses ?
The Omizzy™ server communicates with two
networks: the LAN and an external network via
modem and PPP link.
These two networks must never have the same
address.
What is a gateway ?
A gateway is a device which enables two networks
to communicate with one another.
On a LAN this function is generally performed by
a router.
In this case the gateway address to be entered on
Omizzy™ is the IP address of the router.
Appendix 1: Technical details on IP addressing