Determining Whether Devices Are On The Same Subnet - Extron electronics ISM 824 User Manual

Determining whether devices are on the same subnet

To determine the subnet, the local device's IP address is compared to the remote
device's IP address (figure A-6). Each address's octets 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 local
device's address and the remote device's IP address are unmasked.
Unmasked octets are compared (indicated by ? in figure A-6).
• If the subnet mask octet contains the value 0, the related octets of the local
device's and remote device's IP addresses are masked.
Masked octets are not compared (indicated by X in figure A-6).
If the unmasked octets of the two IP addresses match (indicated by = in figure A-6)
(example 1), the two addresses are on the same subnet.
If the two unmasked fields do not match (indicated by ≠ in figure A-6) (example 2
and example 3), the addresses are not on the same subnet.
Local IP Address:
Subnet Mask:
Remote IP Address:
Match?:
Figure A-6 — Comparing the IP addresses
ISM 824 Integrated Scaling Multiswitcher • Reference Information
Example 1 Example 2
192.168.254.254 192.168.254.254
255.255.0.0 (?.?.X.X) 255.255.0.0 (?.?.X.X)
192.168.2.25 190.190.2.25
≠.≠.X.X — No match
=.=.X.X — Match
(Same subnet) (Different subnet)
Example 3
192.168.254.254
255.255.0.0 (?.?.X.X)
192.190.2.25
=.≠.X.X — No match
(Different subnet)
A-7