User manual

FL SWITCH LM
2-2
PHOENIX CONTACT 7278_en_01
2.1.2.1 Valid IP Parameters
IP parameters comprise the following three elements: "IP address", "subnet mask", and
"default gateway/router".
Valid IP addresses are:
000.000.000.001 to 126.255.255.255
128.000.000.000 to 223.255.255.255
Valid multicast addresses are:
224.000.000.001 to 239.255.255.255
Valid subnet masks are:
255.000.000.000 to 255.255.255.252
Default gateway/router:
The IP address of the gateway/router must be in the same subnetwork as the address of
the switch.
2.1.2.2 Assigning IP Addresses
The IP address is a 32-bit address, which consists of a network part and a user part. The
network part consists of the network class and the network address.
There are currently five defined network classes; Classes A, B, and C are used in modern
applications, while Classes D and E are hardly ever used. It is therefore usually sufficient
if a network device only "recognizes" Classes A, B, and C.
Figure 2-1 Position of bits within the IP address
With binary representation of the IP address the network class is represented by the first
bits. The key factor is the number of "ones" before the first "zero". The assignment of
classes is shown in the following table. The empty cells in the table are not relevant to the
network class and are already used for the network address.
The bits for the network class are followed by those for the network address and the user
address. Depending on the network class, a different number of bits are available, both for
the network address (network ID) and the user address (host ID).
Bit 1 Bit 2 Bit 3 Bit 4 Bit 5
Class A 0
Class B 10
Class C 110
Class D 1110
Class E 11110
Network ID Host ID
Class A 7 bits 24 bits
Class B 14 bits 16 bits
Class C 21 bits 8 bits
Class D 28-bit multicast identifier
Class E 27 bits (reserved)
Bit 1 Bit 32
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