(MAHARANA PRATAP UNIVERSITY OF AGRICULTURE & TECHNOLOGY) Udaipur (Raj.)

A PROJECT REPORT ON INTERNET

PROTOCOL (IP) ADDRESSING

Submitted by:

Ali Asgar Ashiq Hussain

Abhimanyu Kapoor

BE II Year IT

CTAE, Udaipur

Submitted to:

Mr. Dharam Singh

Training In-charge

Department of Information Technology

CTAE, Udaipur

ACKNOWLEDGEMENT

The beatitude, bliss and euphoria that accompany the successful competition

of any task would not be completed without the expression of appreciation of

simple virtues to the people who made it possible. So with reverence, veneration

and honor I acknowledge all those whose guidance and encouragement has made

me successful in winding up this.

First I would like to express my gratitude to Mr. Naveen Malkani for

his valuable guidance encouragement during the completion of training. He was a

major support to me throughout my training, being available with his ideas,

inspiration and encouragement. It is through their masterful guidance that I have

been able to complete my practical training.

The successful completion of training is generally not an individual effort. It

is an outcome of the cumulative effort of a number of persons, each having their

own importance to the objective. This section is a vote of thanks and gratitude all

those persons who have directly or indirectly contributed in their own special way

towards the completion of this dissertation.

Ali Asgar Ashiq Hussain

INTRODUCTION

The internet as we see today is a network of networks, a virtual world

where any computer on internet appears to be connected to every other

computer present on Internet.

The glue that holds the internet together is the IP (Internet Protocol). It

was designed from beginning with internetworking in mind. Its job is to

provide is to provide best-efforts way to transport datagrams from

source to destination, without regard to whether these machines are on

the same network or whether there are other networks in between them.

The Internet Protocol also has the task of routing data packets between

networks, and IP Addresses specify the locations of the source and

destination nodes in the topology of the routing system.

The above window is used to manually configure the IP Address of any

PC running Microsoft Windows. In this the first half is used to configure

IP Address and the second half is used to configure the DNS server.

When the Obtain an IP address automatically is checked the computer

itself finds a DHCP server in the network and obtains an IP address

dynamically from it.

When the Use the following IP address is checked we can manually

assign an IP address to the current Network Interface. It has 3 entries:

IP address: The IP address to be assigned to current Network

Interface.

Subnet Mask: This entry is done automatically by the computer

seeing the IP address assigned. It can also be assigned manually.

Default Gateway: This entry is the IP address of the Gateway

through which the computer can connect to other networks.

IP ADDRESS

An Internet Protocol (IP) address is a numerical identification and

logical address that is assigned to devices participating in a computer

network utilizing the Internet Protocol for communication between its

nodes. Although IP addresses are stored as binary numbers, they are

usually displayed in human-readable notations, such as 208.77.188.166

(for IPv4), and 2001:db8:0:1234:0:567:1:1 (for IPv6).

The designers of TCP/IP defined an IP address as a 32-bit number and

this system, now named Internet Protocol Version 4 (IPv4), is still in use

today. However, due to the enormous growth of the Internet and the

resulting depletion of the address space, a new addressing system (IPv6),

using 128 bits for the address, was developed in 1995 and last

standardized in 1998.

Every host and router on the internet has an IP address, which encodes

its network number and host number. The combination is unique: in

principle, no two machines on the internet have the same IP address. An

IP address does not actually refer to a host, it really refers to network

interface, so if a host is on two network, it must have two IP addresses.

IP versions

The Internet Protocol (IP) has two versions currently in use, the IPv4

and the IPv6. Because of its prevalence, the generic term IP address

typically still refers to the addresses defined by IPv4.

IP version 4 addresses

IPv4 uses 32-bit (4-byte) addresses, which limits the address space to

4,294,967,296 (232

) possible unique addresses. IPv4 reserves some

addresses for special purposes such as private networks (~18 million

addresses) or multicast addresses (~270 million addresses). This reduces

the number of addresses that can be allocated to end users and, as the

number of addresses available is consumed, IPv4 address exhaustion is

inevitable. This foreseeable shortage was the primary motivation for

developing IPv6, which is in various deployment stages around the

world and is the only strategy for IPv4 replacement and continued

Internet expansion.

IPv4 addresses are usually represented in dot-decimal notation (four

numbers, each ranging from 0 to 255, separated by dots, e.g.

208.77.188.166). Each part represents 8 bits of the address, and is

therefore called an octet.

IPv4 Header:

IPv4 networks

In the early stages of development of the Internet protocol network

administrators interpreted an IP address as a structure of network

number and host number. The highest order octet (most significant eight

bits) was designated the network number and the rest of the bits were

called the host identifier and were used for host numbering within a

network. This method soon proved inadequate as additional networks

developed that were independent from the existing networks already

designated by a network number. The Internet addressing specification

was revised with the introduction of Classful Network Architecture.

IP Address Classes Classful network design allowed for a larger number of individual

network assignments. The first four bits of the most significant octet of

an IP address was defined as the class of the address. Three classes, A,

B, and C were defined for universal unicast addressing and Class D was

defined for multicast and Class E was reserved for future use.

Depending on the class derived, the network identification was based on

octet boundary segments of the entire address. Each class used

successively additional octets in the network identifier, thus reducing the

possible number of hosts in the higher order classes (B and C). The

following table gives an overview of this system.

Table

Class A: Class A addresses are specified to networks with large number

of total hosts. Class A allows for 126 networks by using the first octet

for the network ID. The first bit in this octet, is always set and fixed to

zero. And next seven bits in the octet is all set to one, which then

complete network ID. The 24 bits in the remaining octets represent the

hosts ID, allowing 126 networks and approximately 17 million hosts per

network. Class A network number values begin at 1 and end at 127.

Class B: Class B addresses are specified to medium to large sized of

networks. Class B allows for 16,384 networks by using the first two

octets for the network ID. The two bits in the first octet are always set

and fixed to 1 0. The remaining 6 bits, together with the next octet,

complete network ID. The 16 bits in the third and fourth octet represent

host ID, allowing for approximately 65,000 hosts per network. Class B

network number values begin at 128 and end at 191.

Class C: Class C addresses are used in small local area networks

(LANs). Class C allows for approximately 2 million networks by using

the first three octets for the network ID. In class C address three bits are

always set and fixed to 1 1 0. And in the first three octets 21 bits

complete the total network ID. The 8 bits of the last octet represent the

host ID allowing for 254 hosts per one network. Class C network

number values begin at 192 and end at 223.

Class D and E: Classes D and E are not allocated to hosts. Class D

addresses are used for multicasting, and class E addresses are not

available for general use: they are reserved for future purposes.

Subnet Mask The subnet mask is used by the TCP/IP protocol to determine whether a

host is on the local subnet or on a remote network.

In TCP/IP, the parts of the IP address that are used as the network and

host addresses are not fixed, so the network and host addresses above

cannot be determined unless you have more information. This

information is supplied in another 32-bit number called a subnet mask.

Applying a subnet mask to an IP address allows you to identify the

network and node parts of the address. The network bits are represented

by the 1s in the mask, and the node bits are represented by the 0s.

Performing a bitwise logical AND operation between the IP address and

the subnet mask results in the Network Address or Number. The router

uses the Boolean AND operation with an incoming IP address to ‘lose’

the host portion of the IP addresses i.e. the bits that are '0', and match the

network portion with its routing table. From this, the router can

determine out of which interface to send the datagram. This means that

the 'Don't care bits' are represented by binary 0's whilst the 'Do care bits'

are represented by binary 1's.

For example, using our test IP address and the default Class B subnet

mask, we get:

10001100.10110011.11110000.11001000 140.179.240.200 Class B IP

Address

11111111.11111111.00000000.00000000 255.255.000.000 Default

Class B Subnet Mask

--------------------------------------------------------

10001100.10110011.00000000.00000000 140.179.000.000 Network

Address

Default subnet masks:

Class A - 255.0.0.0 - 11111111.00000000.00000000.00000000

Class B - 255.255.0.0 - 11111111.11111111.00000000.00000000

Class C - 255.255.255.0 -

11111111.11111111.11111111.00000000

The same mask is applied throughout the physical networks that share

the same subnet part of the IP address. All devices connected to the

networks that compose the subnet must have the same mask.

Subnets All hosts on a network must have the same network number. This

property of IP addressing can cause problems as networks grow. The

problem is the rule that a single class A, B or C address refers to one

network not a collection of LANs. Thus when many computers are

connected the broadcast requests and other network traffic lead to

network blockages. To avoid this situation we have two options:

Acquire a new network address for each network

Divide the current network into more sub-networks.

Getting a new network address for each sub-network may not be

economical and the IP addresses of the current network get wasted.

The solution is to allow a network to be split into several parts for

internal use but still act like a single network to the outside world. The

parts of the networks are called Subnets.

Sub-netting breaks a network into smaller realms that may use existing

address space more efficiently, and, when physically separated, may

prevent excessive rates of Ethernet packet collision in a larger network.

The technique of sub-netting can operate in both IPv4 and IPv6

networks. The IP address is divided into two parts: the network address

and the host identifier.

Variable Length Subnet Mask

Variable Length Subnet Mask (VLSM) is used by the ISPs to reduce

Wastage of IP Addresses.

A Variable Length Subnet Mask (VLSM) is a means of allocating IP

addressing resources to subnets according to their individual need rather

than some general network-wide rule.

For Example: We require 6 different sub-networks having different

number of computers. Since we require maximum 30 computers in any

network we can take 3 MSBs of Host ID into network ID.

The following comparison shows the wastage of IP Addresses in

Subnetting and VLSM technique:

Requirement

(A)

Subnetting

Before

VLSM (B)

Wastage

(B-A)

Sub-netting

After

VLSM(C)

Wastage

(C-A)

30 30 00 30 00

20 30 10 20 10

10 30 20 14 04

08 30 22 14 06

04 30 26 06 02

02 30 28 02 00

74 180 106 86 22

The VLSM was introduced as a technique to delay the IPv4 Exhaustion.

It was based not on the number of sub-networks required but on the

number of hosts in any particular network. This technique considerably

reduced IP wastage but lead to another problem of routing. VLSM was

not supported by many older routers and switches and hence

implementing them required some hardware up-gradation which was not

economical.

The comparison between IP Network IDs for Subnetting and VLSM

Simple Subnetting Variable Length Subnet Mask

Network ID Subnet Mask Network ID Subnet Mask

192.168.0.32 255.255.255.224 192.168.0.32 255.255.255.224

192.168.0.64 255.255.255.224 192.168.0.64 255.255.255.224

192.168.0.96 255.255.255.224 192.168.0.96 255.255.255.240

192.168.0.128 255.255.255.224 192.168.0.112 255.255.255.240

192.168.0.160 255.255.255.224 192.168.0.128 255.255.255.248

192.168.0.192 255.255.255.224 192.168.0.136 255.255.255.252

Private IP Addresses

In the Internet addressing architecture, a Private Network is a network

that uses private IP address space, following the standards set by RFC

1918 and RFC 4193. These addresses are commonly used for home,

office, and enterprise local area networks (LANs), when globally

routable addresses are not mandatory, or are not available for the

intended network applications. Private IP address spaces were originally

defined in an effort to delay IPv4 address exhaustion, but they are also a

feature of the next generation Internet Protocol, IPv6.

These addresses are characterized as private because they are not

globally delegated, meaning they are not allocated to any specific

organization, and IP packets addressed by them cannot be transmitted

onto the public Internet. Anyone may use these addresses without

approval from a regional Internet registry (RIR). If such a private

network needs to connect to the Internet, it must use either a network

address translator (NAT) gateway, or a proxy server.

The most common use of these addresses is in residential networks,

since most Internet service providers (ISPs) only allocate a single

routable IP address to each residential customer, but many homes have

more than one networked device, for example, several computers and a

video game console. In this situation, a NAT gateway is usually used to

enable Internet connectivity to multiple hosts. Private addresses are also

commonly used in corporate networks, which for security reasons, are

not connected directly to the Internet. In both cases, private addresses

are often seen as enhancing security for the internal network, since it is

difficult for an Internet host to connect directly to an internal system.

The Internet Engineering Task Force (IETF) has directed the Internet

Assigned Numbers Authority (IANA) to reserve the following IPv4

address ranges for private networks, as published in RFC 1918:

RFC19

18

name

IP address

range

number

of

address

es

classful descrip

tion

largest CIDR bl

ock (subnet

mask)

hos

t id

siz

e

24-bit

block

10.0.0.0 –

10.255.255.2

55

16,777,2

16 single class A

10.0.0.0/8

(255.0.0.0)

24

bits

20-bit

block

172.16.0.0 –

172.31.255.2

55

1,048,57

6

16 contiguous

class B's

172.16.0.0/12

(255.240.0.0)

20

bits

16-bit

block

192.168.0.0 –

192.168.255.

255

65,536 256 contiguous

class C's

192.168.0.0/16

(255.255.0.0)

16

bits

Public IP Addresses

The IP Addresses provided by the Internet Service Providers (ISPs) are

called Public IP Addresses. These addresses are recognizable on the

internet and any machine connecting to internet must have a Public IP

Address. These addresses are provided by the Regional Internet

Registries to the ISPs.

The machines which are assigned Private IP Address must go on the

Internet via NAT server having Public IP Address.

The IP Address Ranges not included in the Private IP Address Ranges

are Public IP Ranges.

Broadcast Address

Broadcast address refers to the ability to address a message that is

broadcast to all stations or hosts on a network. Ethernet networks are

shared-media networks in which computers transmit signals on a cable

that all other computers attached to the cable can receive. Thus, all the

computers are part of the same "broadcast domain."

A broadcast address is an IP address that allows you to target all systems

on a specific subnet instead of single hosts. The broadcast address of any

IP address can be calculated by taking the bit compliment of the subnet

mask, sometimes referred to as the reverse mask, and then applying it

with a bitwise OR calculation to the IP address in question.

Normally, one computer transmits frames to only one other computer on

the network by placing the MAC address of the destination computer in

the frame. This frame is then transmitted on the shared media. Even

though other computers see this frame on the network, only the target

receives it. A broadcast message is addressed to all stations on the

network. The destination address in a broadcast message consists of all

1s (0xFFFFFFFF). All stations automatically receive frames with this

address. Normally, broadcast messages are sent for network

management and diagnostic purposes.

On IP networks, the IP address 255.255.255.255 (in binary, all 1s) is the

general broadcast address. You can't use this address to broadcast a

message to every user on the Internet because routers block it, so all you

end up doing is broadcasting it to all hosts on your own network. The

broadcast address for a specific network includes all 1s in the host

portion of the IP address. For example, on the class C network

192.168.1.0, the last byte indicates the host address (a 0 in this position

doesn't refer to any host, but provides a way to refer to the entire

network). The value 255 in this position fills it with all 1s, which

indicates the network broadcast address, so packets sent to

192.168.1.255 are sent to all hosts on the network.

Drawbacks of IPv4

On today’s Internet, IPv4 has the following disadvantages:

Limited address space. The most visible and urgent problem with

using IPv4 on the modern Internet is the rapid depletion of public

addresses. Due to the initial address class allocation practices of

the early Internet, public IPv4 addresses are becoming scarce.

Flat routing infrastructure, i.e. the IP address ranges are not

allocated according to any meaningful hierarchy. In the early

Internet, address prefixes were not allocated to create a

summarizable, hierarchical routing infrastructure. Instead,

individual address prefixes were assigned and each address prefix

became a new route in the routing tables of the Internet backbone

routers. Today’s Internet is a mixture of flat and hierarchical

routing, but there are still more than 85,000 routes in the routing

tables of Internet backbone routers. Thus to reach a router from

one country to another the packet might need to go to a backbone

router in a third country thereby increasing cost and delay.

Security for IPv4 is specified by the use of Internet Protocol

security (IPSec). However, IPSec is optional for IPv4

implementations. Because an application cannot rely on IPSec

being present to secure traffic, an application might resort to other

security standards or a proprietary security scheme. The need for

built-in security is even more important today, when we face an

increasingly hostile environment on the Internet.

Another drawback was the 32 bit header which had much of the

values which were generally never used and which only increased

the bandwidth usage.

A final challenge has been the real-time delivery of multimedia

content and the necessary bandwidth allocation that goes along

with it. A bandwidth allocation method called Quality of Service

(QoS) has been used with IPv4. While QoS does work, there are a

number of different interpretations of the IPv4 QoS standards. This

means that not all QoS-compliant devices are compatible with one

another.

Internet Protocol Version 6

Internet Protocol version 6 (IPv6) is the next-generation Internet

Protocol version designated as the successor to IPv4, the first

implementation used in the Internet that is still in dominant use

currently. It is an Internet Layer protocol for packet-

switched internetworks. The main driving force for the redesign of

Internet Protocol is the foreseeable IPv4 address exhaustion.

The rapid exhaustion of IPv4 address space, despite conservation

techniques, prompted the Internet Engineering Task Force (IETF) to

explore new technologies to expand the Internet's addressing capability.

The permanent solution was deemed to be a redesign of the Internet

Protocol itself. This next generation of the Internet Protocol, aimed to

replace IPv4 on the Internet, was eventually named Internet Protocol

Version 6 (IPv6) in 1995.IPv6 has a vastly larger address space than

IPv4. This results from the use of a 128-bit address, whereas IPv4 uses

only 32 bits. The new address space thus supports 2128

(about 3.4×1038

)

addresses.

This expansion provides flexibility in allocating addresses and routing

traffic and eliminates the primary need for network address

translation (NAT), which gained widespread deployment as an effort to

alleviate IPv4 address exhaustion.

The new design is not based on the goal to provide a sufficient quantity

of addresses alone, but rather to allow efficient aggregation of subnet

routing prefixes to occur at routing nodes. As a result, routing table sizes

are smaller, and the smallest possible individual allocation is a subnet

for 264

hosts, which is the size of the square of the size of the entire IPv4

Internet. IPv6 has facilities that automatically change the routing prefix

of entire networks should the global connectivity or the routing policy

change without requiring internal redesign or renumbering.

Benefits of IPv6

Hierarchical routing infrastructure The Internet is hierarchical in nature, and the IPv6 protocol is designed

with this in mind. Think about it. The computer you're using right now

doesn't have a direct connection to an Internet backbone. Instead, you're

probably behind a NAT firewall, which is connected to an ISP. That ISP

may be connected to another ISP or to a backbone router. Either way, a

packet must make quite a few hops to go from an Internet backbone

router to you.

The IPv6 protocol is designed so that Internet backbone routers will

have much smaller routing tables than they have now. Instead of

knowing every possible route, the routing tables will include routes to

only those routers connected directly to them. The IPv6 protocol will

contain the rest of the information necessary for a packet to reach its

destination.

IPv6 addresses that are reachable on the IPv6 portion of the Internet,

known as global addresses, have enough address space for the hierarchy

of Internet service providers (ISPs) that typically exist between an

organization or home and the backbone of the Internet. Global addresses

are designed to be summarizable and hierarchical, resulting in relatively

few routing entries in the routing tables of Internet backbone routers.

Network security Network security is integrated into the design of the IPv6

architecture. Internet Protocol Security (IPSec) was originally developed

for IPv6, but found widespread optional deployment first in IPv4 (into

which it was back-engineered). The IPv6 specifications

mandate IPSec implementation as a fundamental interoperability

requirement.

The IPv6 protocol has a newly designed IP header. It's designed to make

the protocol more efficient by keeping overhead to a minimum. An IP

packet header is made up of required components and optional

components; in IPv6, the required components are moved to the front of

the header. Optional components are moved to an extension header. This

means that if optional components aren't used, the extension headers

aren't necessary, reducing the packet size.

The downside to the new header is that it isn't compatible with IPv4. If a

router is to handle both IPv4 and IPv6, it must be configured to

recognize both protocols. You can't just set up a router to recognize IPv6

and expect it to be backward-compatible with IPv4.

New configuration options

One of the coolest things about IPv6 is the way it's configured. While

you can still manually configure IPv6, or lease an address from a DHCP

server, there is a new automatic configuration option available. If an un-

configured PC tries to connect to a network that doesn't offer a DHCP

server, the PC can look at either the network's router or the other PCs on

the network and determine an address that would be appropriate for it to

use. This technique is referred to as link local addressing.

Standardized QoS support

IPv6 also includes standardized support for QoS. The QoS

implementation is set up so that routers can identify packets belonging to

an individual QoS flow. This allows those routers to allocate the

necessary amount of bandwidth to those packets. Furthermore, QoS

instructions are included in the IPv6 packet header. This means that the

packet body can be encrypted, but QoS will still function because the

header portion containing the QoS instructions is not encrypted. This

will make it possible to send streaming audio and video over the Internet

with IPSec encryption, but in a manner that guarantees adequate

bandwidth for real-time playback.

Comparison of IPv4 and IPv6 Description IPv4 IPv6

Address 32 bits long (4 bytes).

Address is composed

of a network and a

host portion, which

depend on address

class. Various address

classes are defined: A,

B, C, D, or E

depending on initial

few bits. The total

number of IPv4

addresses is

4,294,967,296.

The text form of the

IPv4 address is

nnn.nnn.nnn.nnn,

where 0<=nnn<=255,

and each n is a

decimal digit. Leading

zeros can be omitted.

Maximum number of

print characters is 15,

not counting a mask.

128 bits long (16 bytes). Basic

architecture is 64 bits for the

network number and 64 bits for the

host number. Often, the host

portion of an IPv6 address (or part

of it) will be derived from a MAC

address or other interface

identifier.

Depending on the subnet prefix,

IPv6 has a more complicated

architecture than IPv4.

The number of IPv6 addresses is

1028

(79 228 162 514 264 337 593

543 950 336) times larger than the

number of IPv4 addresses. The text

form of the IPv6 address is

xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:x

xxx:xxxx, where each x is a

hexadecimal digit, representing 4

bits. Leading zeros can be omitted.

The double colon (::) can be used

once in the text form of an address,

to designate any number of 0 bits.

For example,::ffff:10.120.78.40 is

an IPv4-mapped IPv6 address.

Address

allocation

Originally, addresses

were allocated by

Allocation is in the earliest stages.

The Internet Engineering Task

Description IPv4 IPv6

network class. As

address space is

depleted, smaller

allocations using

Classless Inter-

Domain Routing

(CIDR) are made.

Allocation has not

been balanced among

institutions and

nations.

Force (IETF) and Internet

Architecture Board (IAB) have

recommended that essentially

every organization, home, or entity

be allocated a/48 subnet prefix

length. This would leave 16 bits for

the organization to do subnetting.

The address space is large enough

to give every person in the world

their own /48 subnet prefix length.

Address

mask

Used to designate

network from host

portion.

Not used.

Address

prefix

Sometimes used to

designate network

from host portion.

Sometimes written

as /nn suffix on

presentation form of

address.

Used to designate the subnet prefix

of an address. Written as /nnn (up

to 3 decimal digits, 0 <= nnn <=

128) suffix after the print form. An

example is fe80::982:2a5c/10,

where the first 10 bits comprise the

subnet prefix.

Address

Resolution

Protocol

(ARP)

Address Resolution

Protocol is used by

IPv4 to find a physical

address, such as the

MAC or link address,

associated with an

IPv4 address.

IPv6 embeds these functions

within IP itself as part of the

algorithms for stateless auto-

configuration and neighbor

discovery using Internet Control

Message Protocol version 6

(ICMPv6). Hence, there is no such

thing as ARP6.

Description IPv4 IPv6

Address

scope

For unicast addresses,

the concept does not

apply. There are

designated private

address ranges and

loopback. Outside of

that, addresses are

assumed to be global.

In IPv6, address scope is part of

the architecture. Unicast addresses

have two defined scopes, including

link-local and global; and multicast

addresses have 14 scopes. Default

address selection for both source

and destination takes scope into

account.

Address

types

Unicast, multicast,

and broadcast.

Unicast, multicast, and anycast.

Configuratio

n You must configure a

newly installed

system before it can

communicate with

other systems; that is,

IP addresses and

routes must be

assigned.

Configuration is optional,

depending on functions required.

IPv6 can be used with any Ethernet

adapter and can be run over the

loopback interface. IPv6 interfaces

are self-configuring using IPv6

stateless auto-configuration. You

can also manually configure the

IPv6 interface. So, the system will

be able to communicate with other

IPv6 systems that are local and

remote, depending on the type of

network and whether an IPv6

router exists.

Fragments When a packet is too

big for the next link

over which it is to

travel, it can be

fragmented by the

sender (host or

For IPv6, fragmentation can only

occur at the source node, and

reassembly is only done at the

destination node. The

fragmentation extension header is

Description IPv4 IPv6

router). used.

IP header Variable length of 20-

60 bytes, depending

on IP options present.

Fixed length of 40 bytes. There are

no IP header options. Generally,

the IPv6 header is simpler than the

IPv4 header.

IP header

options

Various options that

might accompany an

IP header (before any

transport header).

The IPv6 header has no options.

Instead, IPv6 adds additional

(optional) extension headers. The

extension headers are AH and ESP

(unchanged from IPv4), hop-by-

hop, routing, fragment, and

destination. Currently, IPv6

supports some extension headers.

IP header

Type of

Service

(TOS) byte

Used by QoS and

differentiated services

to designate a traffic

class.

Designates the IPv6 traffic class,

similarly to IPv4. Uses different

codes. Currently, IPv6 does not

support TOS.

Loopback

address

An interface with an

address

of 127.*.*.*(typically

127.0.0.1) that can

only be used by a

node to send packets

to itself. The physical

interface (line

description) is named

LOOPBACK.

The concept is the same as in IPv4.

The single loopback address

is0000:0000:0000:0000:0000:0000

:0000:0001or ::1 (shortened

version). The virtual physical

interface is named LOOPBACK.

Maximum

Transmissio

n Unit

(MTU)

Maximum

transmission unit of a

link is the maximum

number of bytes that a

IPv6 has an architected lower

bound on MTU of 1280 bytes. That

is, IPv6 will not fragment packets

below this limit. To send IPv6 over

Description IPv4 IPv6

particular link type,

such as Ethernet or

modem, supports. For

IPv4, 576 is the

typical minimum.

a link with less than 1280 MTU,

the link-layer must transparently

fragment and defragment the IPv6

packets.

Network

Address

Translation

(NAT)

Basic firewall

functions integrated

into TCP/IP

configured using

iSeries Navigator.

Currently, NAT does not support

IPv6. More generally, IPv6 does

not require NAT. The expanded

address space of IPv6 eliminates

the address shortage problem and

enables easier renumbering.

Node info

query

Does not exist. A simple and convenient network

tool that should work like ping,

except with content: an IPv6 node

may query another IPv6 node for

the target's DNS name, IPv6

unicast address, or IPv4 address.

Currently, not supported.

PING Basic TCP/IP tool to

test reach ability.

Same for IPv6 and IPv6 is

supported.

Private and

public

addresses

All IPv4 addresses are

public, except for

three address ranges

that have been

designated as private

by IETF :10.*.*.*

(10/8),172.16.0.0 thro

ugh172.31.255.255

(172.16/12) ,

and192.168.*.*

(192.168/16). Private

address domains are

commonly used

IPv6 has an analogous concept, but

with important differences.

Addresses are public or temporary,

previously termed anonymous.

Unlike IPv4 private addresses,

temporary addresses can be

globally routed. The motivation is

also different; IPv6 temporary

addresses are meant to shield the

identity of a client when it initiates

communication (a privacy

concern). Temporary addresses

Description IPv4 IPv6

within organizations.

Private addresses

cannot be routed

across the Internet.

have a limited lifetime, and do not

contain an interface identifier that

is a link (MAC) address. They are

generally indistinguishable from

public addresses.

IPv6 has the notion of limited

address scope using its architected

scope designations.

Quality of

service

(QoS)

Quality of service

allows you to request

packet priority and

bandwidth for TCP/IP

applications.

Currently, the i5/OS

implementation of QoS does not

support IPv6.

Renumberin

g

Done by manual

reconfiguration, with

the possible exception

of DHCP. Generally,

for a site or

organization, a

difficult and

troublesome process

to avoid if possible.

Is an important architectural

element of IPv6, and is largely

automatic, especially within

the/48 prefix.

Route Logically, a mapping

of a set of IP

addresses (might

contain only one) to a

physical interface and

a single next-hop IP

address. IP packets

whose destination

address is defined as

part of the set are

Conceptually, similar to IPv4. One

important difference: IPv6 routes

are associated (bound) to a

physical interface (a link, such as

ETH03) rather than an interface.

One reason that a route is

associated with a physical interface

is because source address selection

functions differently for IPv6 than

Description IPv4 IPv6

forwarded to the next

hop using the line.

IPv4 routes are

associated with an

IPv4 interface, hence,

an IPv4 address.

The default route is

*DFTROUTE.

for IPv4.