Festo SBOC-M-R1B-H, Руководство пользователя

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4. Commissioning
4-7
Festo GDCS-SBOC-EN en 1602a
Netmask Which numbers in an IP address now represent the net ID
and the host ID are defined by the specification of a so-
called “net mask”.
The telephone number of Festo Germany can be used as an
example to explain the IP address and the net mask:
00497113470
Which part of this telephone number is the dialling code and
which represents the subscriber number only becomes clear
when you also know: “The first 7 positions specify the dialling
code, the last 4 the subscriber number”. That is the “net
mask” for the above telephone number.
Net classes The net mask for IP addresses defines, with “0” as a posi­
tion marker, the bytes which are used for addressing the
station (host ID). Networks belong to different net classes,
depending on the number of these bytes:
Net class Netmask Explanation
A 255.0.0.0 Large network
B 255.255.0.0 Medium network
C 255.255.255.0 Small network with max. 254
stations
Tab. 4/1: The most important net classes with the net
masks that belong to them (example)
Gateway Networks with different net-IDs are connected to each other
via a router or gateway. If a station in a network is to send
data to stations in other networks, the IP address of the
gateway must be specified.