Calculating The Number Of Subnets And Nodes - D-Link DES-3326S User Manual

DES-3326S Layer 3 Fast Ethernet Switch User's Guide
The Default subnet masks are:
•
Class A – 11111111.00000000.00000000.00000000
•
Class B – 11111111.11111111.00000000.00000000
•
Class C – 1111111.11111111.11111111.00000000
Additional bits can be added to the default subnet mask for a
given Class to further subnet a network.
logical AND operation is performed between the subnet mask
and the IP address, the result defines the Subnet Address.
Some restrictions apply to subnet addresses. Addresses of all
"0"s and all "1"s are reserved for the local network (when a host
does not know it's network address) and for all hosts on the
network (the broadcast address). This also applies to subnets.
A subnet address cannot be all "0"s or all "1"s. A 1-bit subnet
mask is also not allowed.

Calculating the Number of Subnets and Nodes

To calculate the number of subnets and nodes, use the formula
(2 – 2) where n = the number of bits in either the subnet mask
n
or the node portion of the IP address. Multiplying the number
of subnets by the number of nodes available per subnet gives
the total number of nodes for the entire network.
Example
00001010.00101010.01001001.11010010
Class A IP address
11111111.11100000.00000000.00000000
Subnet Mask
00001010.00100000.00000000.00000000
Network Address
00001010.00101010.11111111.11111111
Broadcast Address
Switch Management and Operating Concepts
255.0.0.0
255.255.0.0
255.255.255.0
When a bitwise
10.42.73.210
255.224.0.0
10.32.0.0
10.32.255.255
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