Chapter 2 Subnetting IPv4 PDF

Chapter 2: Subnetting IP Address IPv4 Subnetting ITE I Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 1  Outlines  Overview of subnetting  Purpose of subnetting  Types of subnetting  Calculations of subnetting ITE 1 Chapter 6 © 2006 Cisco...

Chapter 2: Subnetting IP Address IPv4 Subnetting ITE I Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 1  Outlines  Overview of subnetting  Purpose of subnetting  Types of subnetting  Calculations of subnetting ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 2  What is a subnetting  Subnetting is a process of breaking large network in small networks known as subnets.  Subnetting means in simple barrowing bits for subnet  Allows Creating multiple network from a single address block.  subnetting is an essential technique used in networking to enhance performance, security, and manageability by dividing larger networks into smaller segments.  Each subnet can communicate directly with its devices while routers facilitate communication between different subnets. ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 3  Component of subnetting  A subnet consists of three main elements: 1.Network Address (Subnet ID): This is the first address in the subnet and identifies the subnet itself. 2.Broadcast Address: This is the last address in the subnet and is used to send packets to all devices within that subnet. 3.Subnet Mask: A bitmask that determines which portion of an IP address represents the network and which part represents the host. ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 4  Purpose of subnetting  Maximize addressing efficiency.  Extend the life of IPV4.  Easy to manage.  improves security  Subnetting reduces network traffic by removing collision and broadcast traffic,  Subnetting allows you to apply network security polices at the interconnection between subnets  Improve Network Performance: ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 5  CIDR [ Classless Inter Domain Routing]  CIDR is a slash notation of subnet mask.  CIDR tells us number of on bits in a network address CIDR/ Decimal Binary 25/ 128 10000000 26/ 192 11000000 27/ 224 11100000 28/ 240 11110000 29/ 248 11111000 30/ 252 11111100 ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 6  Subnet Mask  Subnet mask is a 32-bit number that divides an IP address into two parts: the network portion and the host portion.  It determines which part of the IP address identifies the network and which part identifies individual devices (hosts) within that network Class IP address Subnet Mask Binary CIDR/ A 1.0.0.0 255.0.0.0 1111111.00000000.00000000.00000000 24/ B 128.110.0. 255.255.0.0 1111111.1111111.00000000.00000000 16/ 0 C 192.168.1. 255.255.255.0 1111111.1111111.1111111.00000000 8/ 0 ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 7  Classful vs Classless addressing  Classful addressing is an IPv4 addressing architecture that divides addresses into five groups.  This older method divides IP addresses into fixed classes (A, B, C, D, E) based on their leading bits. Each class has a predefined number of networks and hosts, which can lead to inefficient use of IP addresses,  Example Dotted decimal CIDR/ 255.0.0.0 8/ 255.255.0.0 16/ 255.255.0.0 24/ ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 8  Classless  The solution would come in 1993, as Classless Inter-Domain Routing (CIDR) introduced the concept of classless addressing.  Classless addressing, however, decouples IP address ranges from a default subnet mask, allowing for variable-length subnet masking (VLSM).  Using classless addressing and VLSM, addresses can be allocated much more efficiently. This is because It enables more efficient use of the address space by allowing subnets of different sizes  Example Dotted decimal CIDR/ 255.128.0.0 9/ 255.192.0.0 10/ 255.224.0.0 11/ 255.240.0.0 12/ ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 9  Subnetting types  the two subnetting techniques used to divide IP networks are FLSM (Fixed Length Subnet Masking) and VLSM (Variable Length Subnet Masking)  FLSM creates subnets with have the same size and equal number of hots or same subnet  e.g. If a network is divided into four subnets, each subnet will have the same number of addresses.  Easier to manage and configure since all subnets are the same size. ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 10  VLSM  VLSM creates subnets with different subnet masks and sizes based on the specific needs of each subnet.  e.g. A network can have one subnet with a larger mask (more addresses) for a department that needs many hosts, and another subnet with a smaller mask for a department that needs fewer.  Optimizes IP address usage, reducing waste and accommodating varying host requirements. ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 11  Formulas & Variables ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 12  Example:-1  Given IP address 192.168.1.0  Create 2 subnets 192 168 1 0/24 11111111 11111111 11111111 00000000 N N N H –New CIDR length /25 255.255.255.128(Subnet Mask) 192 168 1 0/25 11111111 11111111 11111111 10000000  n = 1 [Number of host bit used in network] n  h = 7 [Remaining host bits] ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 13  Example:-1 cont.… –Total subnets ( 2^n ) :- 2^1 = 2. –Block size (256 - subnet mask) :- 256 - 128 = 128 –Valid subnets 0,128 –Valid host per subnets (2^h-2)=2^7-2=126 Subnets Subnet 1 Subnet 2 Network ID 192.168.1.0 192.168.1.128 First host 192.168.1.1 192.168.1.129 Last host 192.168.1.126 192.168.1.254 Broadcast ID 192.168.1.127 192.168.1.255 ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 14  Example:-2  Given IP address 192.168.1.0  Create 4 subnets 192 168 1 0/24 11111111 11111111 11111111 00000000 N N N H –New CIDR length /26 255.255.255.192(Subnet Mask) 192 168 1 0/26 11111111 11111111 11111111 11000000  n = 2 [Number of host bit used in network] n  h = 6 [Remaining host bits] ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 15  Example:-2 –Total subnets ( 2^n ) :- 22 = 4. –Block size (256 - subnet mask) :- 256 - 192 = 64. –Valid subnets ( Count blocks from 0) :- 0,64,128,192 –Total hosts (2h) :- 26 = 64 –Valid hosts per subnet ( 2^h- 2 ) :- 64 - 2 = 62 Subnets Subnet 1 Subnet 2 Subnet 3 Subnet 4 Network ID 0 64 128 192 First host 1 65 129 193 Last host 62 126 190 254 Broadcast ID 63 127 191 255 ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 16  END ITE 1 Chapter 6 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 17