IP Addressing

What is an IP Address?

An Internet Protocol (IP) address is a number

that identifies a device on a computer network.

IP HISTORY AND MANAGEMENT

User

Assignment

ISP

Allocation

RIR*Allocation

IANAIP

Address Management Today

IETF

RIR : Representative of ISP

In 1992 – 2001

Recent years: 2002 – 2009

2004:

Establishment of the Number Resource Organisation

RIR (Regional Internet Registries A regional Internet registry (RIR) is an organization

overseeing the allocation and registration of Internet Number resources within a particular region of the world. Resources include IP addresses.

There are currently five RIRs in operation:

American Registry for Internet Numbers (ARIN) for North America and parts of the Caribbean

RIPE Network Coordination Centre (RIPE NCC) for Europe, the Middle East and Central Asia

Asia-Pacific Network Information Centre (APNIC) for Asia and the Pacific region

Latin American and Caribbean Internet Addresses Registry (LACNIC) for Latin America and parts of the Caribbean region

African Network Information Centre (AfriNIC) for Africa

Address consists of 32 Bits Represented in A.B.C.D where A represent

Decimal Value of 8 Bits or 1 Byte A range from 0-255.

IPv4

Few Examples of Binary conversions Binary to Decimal Decimal to Binary

Binary Understanding

Unicast◦ One to One Communication

Multicast◦ One to Many Communication

Broadcast◦ One to All Communication

Ways of Communication

Type of Communication (Contd)

A Class B Class C Class D Class (Reserve for Multicasting) E Class (Reserve for Scientific Research)

IP Address Classes

IP Classes

IP Address◦ Network Bits

Common among all the users on same Network◦ Host Bits

Unique Bits to Identify the Host on the LAN segment

Understanding IP Address

Network – ID ◦ Represent all the Host on the Network◦ Cannot be assigned to Users◦ When all the HOSTID portion bits of an IP address are zero’s then it is

called Network Address.

class A 10.0.0.0 class B 172.16.0.0 class C 192.168.10.0

Broadcast – ID◦ Address to send Packet to all the Host on the Network◦ Cannot be assigned to the Users◦ When all the HOSTID portion bits of an IP address are one’s then it is

called Broadcast Address.

class A 10.255.255.255 class B 172.16.255.255 class C 192.168.10.255

Addresses

Host – ID ◦ Address assigned to Host on the Network◦ All Host must have the Unique Host-ID

Default Address◦ When all the NETID as well as HOSTID portion bits of an IP address are 0’s

then it is used for Default Routing (CISCO Routers) Address 0.0.0.0

Loopback Addresses (Self Testing)

Address 127.0.0.0

APIPA Address(Automatic Private IP Address) Address 169.254.0.0

Subnet Mask:- It is used to represent the Network bits in the IP address.◦ 1 represent the corresponding bit in IP address is

Network Bit◦ 0 represent the corresponding bit in IP address is

Host BitSubnet Mask Helps to identify the Host in the Given

Network-IdEx.192.168.0.0 255.255.255.0

Subnet Mask

Class Less Inter domain Range◦ It is the Decimal representation of the no. of

Network bits in the IP Address

For Example◦ 192.168.0.0 /24◦ 172.16.0.0 /16◦ 10.0.0.0 /8

CIDR

Subnetting:- Is concept to break down the bigger Network into two or more than two smaller Network.

Subnetting

To identify subnets, you will “borrow” bits from the host ID portion of the IP address:

The number of subnets available depends on the number of bits borrowed. The available number of subnets = 2s, I which s is the

number of bits borrowed.The number of hosts per subnet available depends

upon the number of host ID bits not borrowed. The available number of hosts per subnet = 2h -2, in

which h is the number of host bits not borrowed. One address is reserved as the network address. One address is reserved as the broadcast address.

Subnetting Review

Possible Subnets and Hosts for a Class C Network

Possible Subnets and Hosts for a Class B Network

Possible Subnets and Hosts for a Class A Network

IP-SUBNET ZERO OR FLSM Subnetting is based up on NETID portion bits. In this case we need to borrow some bits from Host ID portion that

depends up on the number of subnets For e.g 192.168.10.0/26

Step 1: Identify the total number of subnets (how many)? 2n = number of subnets 22 = 4Where n are the number of borrowed bits from hostId portion. Step 2: Identify the the total number of hosts for each subnets (how many)? 2m - 2 = number of valid hosts 26 – 2 = 62Where m are remaining number of bits in hostid portion.

Step 3: Calculate Subnet Mask and Range. 11111111 11111111 11111111 11000000 255 .255 .255 .192 Range:256 - 192 = 64

Step 4: Identify the total number of subnets (Which one)? (i) 192.168.10.0 (ii) 192.168.10.64 (iii) 192.168.10.128 (iv) 192.168.10.192Step 5: Identify the valid number of host for each subnet (which one)? (i) 192.168.10.1 -- 192.168.10.62 (ii) 192.168.10.65 -- 192.168.10.126 (iii)192.168.10.129 -- 192.168.10.190 (iv) 192.168.10.193 -- 192.168.10.254 Step 6:Identify the broadcast address for each subnet? (i) 192.168.10.63 (ii) 192.168.10.127 (iii)192.168.10.191 (iv)192.168.10.255

Subnet a network with a private network address of 172.16.0.0./16 so that it provides 100 subnets and maximizes the number of host addresses for each subnet.

◦ How many bits will need to be borrowed?◦ What is the new subnet mask?◦ What are the first four subnets?◦ What are the range of host addresses for the four

subnets?

Subnetting Review Exercise

Subnetting has limitation of only Splitting the network into smaller symmetrical networks.

Variable Length Subnet Mask (VLSM)◦ VLSM Provides the use of Subnetting in more

effective way.◦ Allow to splitting the network into smaller

asymmetrical networks.Ex :- 192.168.1.0/25, 192.168.1.128/26,

192.168.1.192/27, 192.168.1.224/28, 192.168.1.240/29

VLSM

What Is a Variable-Length Subnet Mask?

Subnet 172.16.14.0/24 is divided into smaller subnets.

– Subnet with one mask (/27).

– Then further subnet one of the unused /27 subnets into multiple /30 subnets.

A Working VLSM Example

A Working VLSM Example (Cont.)

A Working VLSM Example (Cont.)

A Working VLSM Example (Cont.)

Understanding Route Summarization

Routing protocols can summarize addresses of several networks into one address.

◦ Classful routing protocols do not include the subnet mask with the network in the routing advertisement.

◦ Within the same network, consistency of the subnet masks is assumed, one subnet mask for the entire network.

◦ Summary routes are exchanged between foreign networks.◦ Examples of classful routing protocols include:

RIPv1 IGRP

Note: Classful routing protocols are legacy routing protocols typically used to address compatibility issues. RIP version 1 and Interior Gateway Routing Protocol (IGRP) are introduced to provide examples.

Classful Routing Overview

Classless routing protocols include the subnet mask with the network in the advertisement.

Classless routing protocols support VLSM; one network can have multiple masks.

Summary routes must be manually controlled within the network.Examples of classless routing protocols include: RIPv2, EIGRP, OSPF

RIPv2 and EIGRP act classful by default, and summary routes are exchanged between foreign networks. The no auto-summary command forces these

protocols to behave as if they are classless.

Classless Routing Overview

Summarizing Within an Octet

Summarizing Addresses in a VLSM-Designed Network

Route Summarization Operation in Cisco Routers

192.16.5.33 /32        Host192.16.5.32 /27 Subnet192.16.5.0 /24 Network192.16.0.0 /16 Block of Networks0.0.0.0 /0 Default

Supports host-specific routes, blocks of networks, and default routes

Routers use longest prefix match

Summarizing Routes in a Discontiguous Network

Classful RIPv1 and IGRP do not advertise subnets, and therefore cannot support discontiguous subnets.

Classless OSPF, EIGRP, and RIPv2 can advertise subnets, and therefore can support discontiguous subnets.

◦ Subnetting lets you efficiently allocate addresses by taking one large broadcast domain and breaking it up into smaller more manageable broadcast domains.

◦ VLSMs let you more efficiently allocate IP addresses by adding multiple layers of the addressing hierarchy.

◦ The benefits of route summarization include smaller routing tables and the ability to isolate topology changes.

Summary

1. 255.0.0.0:/82. 255.128.0.0:/93. 255.192.0.0:/10 4. 255.224.0.0:/11 5. 255.240.0.0:/12 6. 255.248.0.0:/13 7. 255.252.0.0:/14 8. 255.254.0.0:/15 9. 255.255.0.0:/1610.255.255.128.0:/17 11.255.255.192.0:/18 12.255.255.224.0:/19 13.255.255.240.0:/2014.255.255.248.0:/21 15.255.255.252.0:/2216.255.255.254.0:/23 

A：

17. 255.255.255.0:/24

18. 255.255.255.128:/25 

19. 255.255.255.192:/26

20. 255.255.255.224:/27

21. 255.255.255.240:/28

22. 255.255.255.248:/29

23. 255.255.255.252:/30 

Addressing Summary ExampleAddressing Summary Example

10101100

11111111

10101100

00010000

11111111

00010000

11111111

00000010

10100000

11000000

10000000

00000010

10101100 00010000 00000010 10111111

10101100 00010000 00000010 10000001

10101100 00010000 00000010 10111110

Host

Mask

Subnet

Broadcast

Last

First

172.16.2.160

255.255.255.192

172.16.2.128

172.16.2.191

172.16.2.129

172.16.2.190

1

2

3

4

56

7

89

16172 2 160

B：