Extron Electronics MGP Pro Series User Guide - Manual (Page 116)

MGP Pro Series • Reference Information 110
Exiting Telnet (Quit command)
Exit the Telnet utility by entering quit at the Telnet prompt. If you are connected to the
MGP Pro, access the Telnet prompt by entering the Escape sequence ( ] >).
Subnetting, a Primer
A subnet is a subset of a network — a set of IP devices that have portions of their IP
addresses in common. It is not the purpose of this guide to describe TCP/IP protocol
in detail. However, some understanding of TCP/IP subnetting is necessary in order to
understand the interaction of the MGP Pro and the mail server gateway. To understand
subnetting at the level required to install and operate the MGP Pro, you must understand
the concepts of a gateway, local and remote devices, IP addresses and octets, and subnet
masks and octets.
Gateways
The MGP Pro can communicate with the e-mail server that it 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 guide, subnetting is an issue when you are using the controlling computer
to set TCP/IP and e-mail values via SIS commands on the MGP Pro (see
IP Setup
Commands beginning on page 73 and Email Commands , also on page 73). When you
are setting up the variables for e-mail notification, the MGP Pro 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 sub-fields, called “octets,” which
are separated by dots (periods) (figure 49). Each octet can be numbered from 000 through
255. Leading zeros, up to 3 digits total per octet, are optional. Values of 256 and above are
invalid.
192.168.254.254 Typical IP Address:
Octets
Figure 48. IP Address and Octets
Subnet masks and octets
The subnet mask (figure 50) 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 zeros, up
to 3 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 49. Subnet Mask and Octets