Subnetting And Subnet Masks - Tripp Lite SNMP Solo MT-SE-37/02 Owner's Manual

number of octets reserved for the network ID and the number of
octets reserved for the host ID.
Class Value of First Network ID
Octet
A 1-126
B 128-191 first two octets
C 192-223
Any value between 0 and 255 is valid as a host ID octet except
for those values the InterNIC reserves for other purposes.
Value Purpose
0, 255 Subnet masking
Loopback testing and interprocess communication
127
on local devices
224-254 IGMP multicast and other special protocols

Subnetting and Subnet Masks

Subnetting divides a network address into subnetwork
addresses to accommodate more than one physical network on
a logical network.
For example: A Class B company has 100 LANs (Local Area
Networks) with 100 to 200 nodes on each LAN. To classify the
nodes by its LANs on one main network, this company
segments the network address into 100 subnetwork addresses.
(If the Class B network address is 150.1.x.x, the address can be
segmented further from 150.1.1.x through 150.1.100.x.)
A subnet mask is a 32-bit value that distinguishes the network
ID from the host ID for different subnetworks on the same
logical network. Like IP addresses, subnet masks consist of four
octets in dotted decimal notation. You can use subnet masks to
route and filter the transmission of IP packets among your
subnetworks. The value "255" is assigned to octets that belong
to the network ID, and the value "0" is assigned to octets that
belong to the host ID.
For the example above, if you want all the devices on the
subnetworks to receive each other's IP packets, set the subnet
mask to 255.255.0.0. If you want the devices on a single
subnetwork only to receive IP packets from other devices on its
Host ID
first octet last three octets
last two octets
first three last octet
octets
Appendix
Tripp Lite
Number of
Hosts
16,387,064
64,516
254
31