Extron electronic Ultra Series - Manual (Page 188)

Ethernet Connection, cont’d
CrossPoint / MAV Matrix Switchers • Ethernet Connection A-6
Subnetting — A Primer
It is not the purpose of this manual to describe TCP/IP protocol in detail. However,
some understanding of TCP/IP subnetting (a subnet is a subset of a network — a
set of IP devices that have portions of their IP addresses in common) is necessary
in order to understand the interaction of the CrossPoint or MAV switcher and the
mail server gateway. To understand subnetting at the level required to install and
operate the CrossPoint or MAV switcher, you must understand the concepts of a
gateway, local and remote devices, IP addresses and octets, and subnet masks and
octets.
Gateways
The CrossPoint or MAV switcher can communicate with the e-mail server that the
switcher uses for e-mail notification directly (if they are on the same subnet) or
the communication can be routed via a gateway (a computer that provides a link
between different subnets).
Local and remote devices
The local and remote devices are defined from the point of view of the function
being described. In this manual, subnetting is an issue when you are using the
controlling PC to set TCP/IP and e-mail values in the CrossPoint or MAV switcher
(see “IP Settings/Options window” in chapter 5, “Matrix Software”, and “Email
Settings page” in chapter 6, “HTML Operation”). When you are setting up the
variables for e-mail notification, which may include subnetting, the matrix switcher
is the local device and the e-mail server is the remote device.
IP addresses and octets
Valid IP addresses consist of four 1-, 2-, or 3-digit numeric subfields, properly called
octets, separated by dots (periods) (figure A-4). 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.
192.168.254.254 Typical IP Address:
Octets
Figure A-4 — IP address and octets
Subnet masks and octets
The subnet mask (figure A-5) 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.
255.255.0.0 Typical Subnet Mask:
Octets
255 indicates that this octet will be
compared between two IP addresses.
0 indicates that this octet will not be
compared between two IP addresses.
Figure A-5 — Subnet mask and octets