Transcript IP Addressing Part 2 - Computer Techniques, Inc.

CTI Technician Training
Internet Protocol
Part 2
Review
Is this address on your network?
Your info
208.8.16.7
255.255.255.224
No it is not.
Destination IP
208.8.16.47
Convert IP and subnet mask to binary.
11010000.00001000.00010000.00000111
11111111.11111111.11111111.11100000
11010000.00001000.00010000.00101111
Draw a line between network bits and host bits.
Convert Destination IP to binary.
Check to see if network bits match.
Don’t Match
Calculating hosts from a mask
Number of hosts per subnet can be calculated by finding
all of the possible host addresses. (Remember not to
count the network id and broadcast address.)
The formula used for calculating number of hosts is:
2n-2
n = number of host bits
You have to -2 because the network id and broadcast
address cannot be used as host addresses.
Subnetting
Definition
Dividing a larger network into smaller,
equally sized networks.
Example: If given a /16 network, it can be
divided into 256 separate /24 networks.
Calculating networks from a subnet mask
To find the number of subnets available, you must find
the difference of bits between the larger mask and the
smaller mask.
The formula used for calculating number of subnets is:
2n
n = number of bits difference
If given a /20 network, how many /24 networks can we
get out of it?
24 = 16
Finding valid network id’s
To find valid network id’s, you must first know the
network id of your large network.
Next, you need to know what size networks you would
like to subnet to.
Find the number of smaller networks you will have. (2n)
Find the value of the last bit of the smaller subnet mask.
This will be the increments to count by to find valid
network id’s. Continue counting by that number until you
reach the last network id.
Subnetting Example
You have been assigned 208.6.96.0 /20
How many /23 networks can you create?
2(23-20) = 23 = 8 networks
What are their network id’s?
Find the least significant bit position for /23
11111111.11111111.11111110.0000000
Count in increments of 2
208.6.96.0, 208.6.98.0, 208.6.100.0, 208.6.102.0,
208.6.104.0, 208.6.106.0, 208.6.108.0, 208.6.110.0
Variable Length Subnet Masks
VLSM simply means that your smaller
networks do not have to be the same size.
Example: If you have been provided a
/22, you can subnet one /23 and two /24
networks.
VLSM Example
A /21 network could be subnetted as follows:
/22
/22
/23
/23
/24
/24
/25
/25
/26
/26
/27 /27 /27 /27
/27
/27
/30 /30 /30 /30 /30 /30 /30 /30
/28
/28
/29
/29
/30
/30
Questions or Comments?
Adam Vocks - MCP, MCSE
Vice-President
Computer Techniques, Inc.
[email protected]