Ip Addresses And Octets; Subnet Masks And Octets; Determining Whether Devices Are On The Same Subnet - Extron electronics FOX Matrix 320x User Manual

IP Addresses and Octets

Valid IP addresses consist of four 1-, 2-, or 3-digit numeric subfields, properly called
"octets," separated by dots (periods) (see figure 53). Each octet can be numbered from 000
through 255. Leading zeroes, up to three digits total per octet, are optional. Values of 256
and above are invalid.
Typical IP Address:
Figure 53.

Subnet Masks and Octets

The subnet mask (see figure 54) is used to determine whether the local and remote devices
are on the same subnet or different subnets. The subnet mask consists of four numeric
octets separated by dots. Each octet can be numbered from 000 through 255. Leading
zeroes, up to three digits total per octet, are optional. Each octet typically contains either
255 or 0. The octets determine whether or not the same octets of two IP addresses will be
compared when determining if two devices are on the same subnet.
255 indicates that this octet will be
compared between two IP addresses.
Typical Subnet Mask:
Figure 54.

Determining Whether Devices Are on the Same Subnet

To determine the subnet, the IP address of the local device is compared to the IP address
of the remote device (see figure 55). The octets of each address are compared or not
compared, depending on the value in the related subnet mask octet.
• If a subnet mask octet contains the value 255, the related octets of the IP addresses of
the local device and the remote device are unmasked.
Unmasked octets are compared (indicated by
• If the subnet mask octet contains the value 0, the related octets of the IP addresses of
the local device and remote device are masked.
Masked octets are not compared (indicated by
If the unmasked octets of the two IP addresses match (indicated by
the two addresses are on the same subnet.
If the two unmasked fields do not match (indicated by
example 3), the addresses are not on the same subnet.
Local IP Address:
Subnet Mask:
Remote IP Address:
Figure 55.
192.168.254.254
Octets
Typical IP Address
0 indicates that this octet will not be
compared between two IP addresses.
255.255.0.0
Octets
Typical Subnet Mask
Example 1
192.168.254.254
255.255.0.0 (?.?.X.X)
192.168.2.25
Match?: =.=.X.X — Match
(Same subnet)
Comparing the IP Addresses of the Local and Remote Devices
FOX Matrix 320x and FOX Matrix 14400 • Ethernet Connection
? in figure 55).
X in figure 55).
=
in figure 55, example 1),
≠
in figure 55, example 2 and
Example 2 Example 3
192.168.254.254 192.168.254.254
255.255.0.0 (?.?.X.X) 255.255.0.0 (?.?.X.X)
190.190.2.25 192.190.2.25
— No match =.≠.X.X
≠.≠.X.X
(Different subnet) (Different
— No match
subnet)
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