SI-PROFINET RT User Guide
15
Issue Number: 2
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5.3
Setting the IP address
Each device on a network must have it's own unique IP address, if the network is not to
be connected to other networks or the Internet, then the assignment of the IP addresses
is not critical (although using a standard system is recommended). The issue of address
assignment becomes more important when connecting multiple networks together or
connecting to the Internet where there is a strong possibility of address duplication
unless a standard addressing system is used.
The IP address and subnet mask will be determined during the network configuration
setup and, along with the device name, programmed into the module during
parameterization.
When selecting IP addresses, the following points should be considered:
•
Reserve adequate address space
: Ensure you have enough reserve address
space on your chosen addressing scheme to allow for future expansion
•
Uniqueness
: Ensure all your addresses are unique
•
Avoid reserved addresses
: Some addresses are reserved and should not be
used. (e.g. 127.0.0.1 is a loop-back address)
•
Broadcast and system addresses
: The highest and lowest host addresses are
used for broadcasts and system addressing and should not be used
•
Use a system
: Adopt a scheme to assign IP addresses, for example, reserve
ranges of addresses for specific uses such as servers, routers, work stations etc.
5.4
IP address classes
IP addresses are grouped into five classes, each class has a specific set of addresses
and typical situation where it is used. When selecting the class of IP addresses to use,
consideration must be given to the number of subnets and hosts that are required.
Table 5-1
IP address class configuration
on page 15 shows how the class types are
defined.
Table 5-1 IP address class configuration
Network ID's and host ID's with all 0's or all 1's specify a broadcast address and are
therefore not included as valid networks.
Class
First byte
range
Valid networks
Number of
subnets
Host
component
Number of
hosts
A
1 - 126
1.0.0.1
to
126.255.255.254
126
x.y.z
16,777,214
B
128 - 191
128.0.0.1
to
191.254.255.254
16,382
y.z
65,534
C
192 - 223
192.0.0.1
to
223.255.254.254
2,097,150
z
254
D
224 - 239
Multicast group ID
E
240 - 255
Reserved
NOTE
