vlsm and supernetting

Presentation On

VLSM & Supernetting

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Group Members:1. Md. Omor Faruk ID: 151-15-54442. Nahian Ahmed ID: 151-15-51373. Monsur Ahmed Shafiq ID: 151-15-54394. Md. Sajibul Hasan ID: 151-15-49865. Md. Taikul Islam ID: 151-15-5144

05/02/2023 VLSM & Supernetting

Contains:• Introduction• History of VLSM • Basic knowledge about Subnet Masking• Process of Subnet Masking• Steps of Variable Length Subnet Masking(VLSM)• Implementing VLSM• History of Supernetting• Basic knowledge about Supernetting• Steps of Supernetting• Implementation of Supernetting


History of VLSMClassless Inter-Domain Routing (CIDR) is a method for allocating IP addresses and IP routing. The Internet Engineering Task Force introduced CIDR in 1993 to replace the previous addressing architecture of classful network design in the Internet.

Classless Inter-Domain Routing is based on variable-length subnet masking (VLSM), which allows a network to be divided into variously sized subnets, providing the opportunity to size a network more appropriately for local needs.

What is VLSM ?

• Subnetting of a subnet.• The more realistic way of Subnetting.• To make the most efficient use of all the bits of a

network.• Prevent network and host from waste.


•Steps of VLSM:

• Find the largest segment which need largest number of hosts address.• Do Subnetting to fulfill the requirement of largest segment.• Assign the appropriate subnet mask for the largest segment.• For second largest segments, take one of these newly created subnets and

use different subnet mask for this one.• It will cover from the large number host first.• Repeat this process until the last network.


VLSM Examples

VLSM Examples(cont.)• We have 192.168.1.1/24

192.168.1.1/24192.168.1.1/24

192.168.1.0/25126 Hosts

192.168.1.128/25126 Hosts


192.168.1.0/25

192.168.1.0/2662 Hosts

192.168.1.64/2662 Hosts

Assign To A which need 50 hosts Assign To B which need 50 hosts


192.168.1.128/25

192.168.1.128/2662 Hosts

192.168.1.192/2662 Hosts

Assign To C which need 40 hosts We can assign in D but ……


192.168.1.192/26

192.168.1.192/2730 Hosts

192.168.1.224/2730 Hosts

Assign To D which need 20 hosts May be in future……

Why use VLSM • Because of Addressing crisis.• The Internet Engineering Task Force identified two problems in

1992 ----IPv4 may not enough in future----Rapid increase of internet user.

**Freedom to use different subnet masks for networks within a single autonomous system.

Advantage of VLSM• We can divide our Network in to many area.• It helps ISP to allocate more host.• Save our Host IP Addresses.• VLSM is supported by : 1.OSPF 2.Integrated IS-IS 3.RIPv2 4.Static Routing

VLSM VS CIDRVLSM: 1 bit subnetting of Network address.

CIDR : IP network is represented by a prefix, which is an IP address and some indication of the length of the mask

VLSM VS Supernetting

Introduction of Supernetting


• Reverse process of VLSM

• Creating larger network.

• Combination of two or more networks (or subnets).

• This method facilitates regional route aggregation.

Basic Knowledge of Supernetting:

• Need two or more Network or Subnets.• Make the decimal network into binary value.• Counting 0 and 1.• Supernetting requires the use of routing protocols

that support Classless Inter-Domain Routing (CIDR).


Steps of Supernetting:

• Contain many IP or network.• Write down IP serially then convert into binary.• Find matching from left site and underline upto match.• Write upto match and make “0” zero upto end.• Put dot (.) after the (8) eight interval.• Make decimal from the binay of each portion which will be

the new network address.• Make all (1) upto match and zero upto end which will be the

musk.


Supernetting Scenario

Implementation of Supernetting:

Make a Summation of the following network: 192.168.98.0 , 192.168.99.0 , 192.168.100.0 , 192.168.101.0, 192.168.102.0 , 192.168.105.0

Firstly, the addresses are converted to binary format and aligned in a list:



Results:

Secondly, the bits at which the common pattern of digits ends are located. These common bits are shown in red.

Lastly, the number of common bits is counted. The summary route is found by setting the remaining bits to zero, as shown below. It is followed by a slash and then the number of common bits.

The summarized route is 192.168.96.0/20. The subnet mask is 255.255.240.0.

Advantages & Disadvantage of Supernetting:Advantages:• Control and reduce the network traffic.• Helpful to solve the problem of lacking IP addresses.• To minimize the size of the routing tables.In the near future the newer Wireless Scalable Access System models will use smart supernetting device.

Disadvantages:• It cannot cover different area of a network when combined.• All the networks should be in the same class.

Thank You!If You Have any Question

vlsm and supernetting

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