Computer-Network-PowerPoint-Slide

1. WELCOME
PRESENTATION:
Variable Length Subnet
Masking (VLSM)

2. “
Md Moynul Hossain Sir
Name:
I’d: 201-15-3326
Sec: PC-Q
Student Of DIU…
Name: Adnan Faizal
I’d: 201-15-3472
Sec: PC-Q
Student Of DIU…
Name: Monoronjon Dutta
I’d: 201-15-3660
Sec: PC-Q
Student Of DIU…
Name: Fawziyah Akter
I’d: 201-15-3595
Sec: PC-Q
Student Of DIU…
Lecturer at CSE
Daffodil International
University

3. => Several new methods of addressing were created so that
usage of IP space was more efficient. The first of these
methods is called Variable-Length Subnet Masking (VLSM).
Subnetting had long been a way to better utilize address
space. Subnets divide a single network into smaller pieces.
This is done by taking bits from the host portion of the
address to use in the creation of a “sub” network.
For example, take the class B network 147.208.0.0. The
default network mask is 255.255.0.0, and the last two octets
contain the host portion of the address. To use this address
space more efficiently, we could take all eight bits of the third
octet for the subnet.
Introduction to
(VLSM)

4. “
VLSM stands for Variable Length Subnet Mask where
the subnet design uses more than one mask in the
same network which means more than one mask is
used for different subnets of a single class A, B, C or a
network. It is used to increase the usability of subnets
as they can be of variable size. It is also defined as the
process of subnetting of a subnet.
=>Variable-length subnet mask
=>Classful allows only one subnet in a network
>one subnet in an autonomous system
=>Maximizing the use of address (Subnet Zero)
=>“Subnetting a Subnet”
=>Routing that support VLSM
=>OSPF, Integrated IS-IS, EIGRP, RIPv2, and static routing.
What is (VLSM) ?

5. Why VLSM ?
⇒ VLSM provides many benefits for real networks, mainly related to how you
allocate and use your IP address space. Because a mask defines the size of
the subnet (the number of host addresses in the subnet), VLSM allows
engineers to better match the need for addresses with the size of the
subnet.
VLSM Provides for route summarization on non- classfull boundaries. Such
as:
# Reduces the size of a routing table.

6. Configuration of VLSM
This Figure shows a typical choice of using a
/30 prefix (mask 255.255.255.252) on point-
to-point serial links, with mask /24
(255.255.255.0) on the LAN subnets. All
subnets are of Class A network 10.0.0.0, with
two masks being used, therefore meeting the
definition of VLSM.
VLSM is simply a side effect of using the
ip address interface subcommand.
Routers collectively configure VLSM by
virtue of having IP addresses in the
same classful network but with different
masks.

7. Procidure Of (VLSM)
Step 01: Make a list of Subnets possible.

8. Step 02:
Sort the requirements of IPs in descending order (Highest to Lowest).
• Sales 100
• Purchase 50
• Accounts 25
• Management 5

9. Step 03:
Allocate the highest range of IPs to the highest requirement, so let's
assign 192.168.1.0 /25 (255.255.255.128) to the Sales department.
This IP subnet with Network number 192.168.1.0 has 126 valid Host IP
addresses which satisfy the requirement of the Sales department. The
subnet mask used for this subnet has 10000000 as the last octet.

10. Step 04:
Allocate the next highest range, so let's assign 192.168.1.128 /26
(255.255.255.192) to the Purchase department. This IP subnet with
Network number 192.168.1.128 has 62 valid Host IP Addresses which
can be easily assigned to all the PCs of the Purchase department. The
subnet mask used has 11000000 in the last octet.

11. Step 05:
Allocate the next highest range, i.e. Accounts. The requirement of 25
IPs can be fulfilled with 192.168.1.192 /27 (255.255.255.224) IP
subnet, which contains 30 valid host IPs. The network number of
Accounts department will be 192.168.1.192. The last octet of subnet
mask is 11100000.

12. Step 06:
Allocate the next highest range to Management. The
Management department contains only 5 computers. The
subnet 192.168.1.224 /29 with the Mask 255.255.255.248
has exactly 6 valid host IP addresses. So this can be assigned
to Management. The last octet of the subnet mask will
contain 11111000.
By using VLSM, the administrator can subnet the IP subnet in
such a way that least number of IP addresses are wasted.
Even after assigning IPs to every department, the
administrator, in this example, is still left with plenty of IP
addresses which was not possible if he has used CIDR.

13. Have You Any Query?
THANK YOU..