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Oct 23, 2013 (3 years and 9 months ago)

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TCP/IP

TCP/IP Introduction

What is TCP/IP?



TCP/IP

is

a

name

given

to

the

collection

(or

suite)

of

networking

protocols

that

have

been

used

to

construct

the

global

Internet
.



TCP/IP

was

invented

by

Robert

Kahn

(

Member

of

ARPA

(Advance

Research

Project

Agency,A

Part

of

Department

of

Defence))

and

Vinton

G
.

in

year

1974
.

Vinton

has

invented

IP(Internet

Protocol)
.


The

TCP/IP

name

is

taken

from

two

of

the

fundamental

protocols

in

the

collection,

IP

and

TCP
.



TCP/IP

protocols

are

not

used

only

on

the

Internet
.

They

are

also

widely

used

to

build

private

networks(intranet),

that

may

or

may

not

be

connected

to

the

global

Internet
.


The

network,

implemented

with

the

TCP/IP

suite

of

protocols,

is

a

packet
-
switched

network
.


A

packet
-
switched

network

transmits

information

about

the

network

in

small

segments,

called

packets
.

For

example,

if

one

computer

transmits

a

lengthy

file

to

another

computer,

the

file

is

divided

into

many

packets

at

the

origin

and

then

reassembled

at

the

destination
.



The

TCP/IP

protocols

define

the

format

of

each

packet,

as

well

as

the

way

computers

on

the

networks

receive

and

retransmit

packets
.

This

definition

includes

the

origin

of

the

packet,

the

destination

of

the

packet,

the

length

of

the

packet,

and

the

type

of

packet
.




The TCP/IP Suite of Protocols




The

protocols

in

the

TCP/IP

suite

roughly

correspond

to

a

network

communications

model

defined

by

the

International

Organization

for

Standardization

(ISO)
.

This

model

is

called

the

Open

Systems

Interconnection

(OSI)

reference

model
.

The

OSI

model

describes

an

ideal

computer

network

system

in

which

communication

on

the

network

occurs

between

processes

at

discrete

and

identifiable

layers
.

Each

layer

on

a

given

host

provides

services

to

the

layers

above

it

and

receives

services

from

the

layers

below

it
.




Now

we

will

see

the

seven

layers

of

the

OSI

reference

model,

as

defined

by

ISO,

and

the

roughly

corresponding

layers

of

the

TCP/IP

protocol

suite
.



OSI Reference Model and Corresponding TCP/IP Layers


some of the more common protocols in the TCP/IP suite and the services they
provide:



Protocol



Service



Internet Protocol (IP)



Provides packet delivery services (routing) between






nodes.



Internet Control Message Protocol (ICMP)


Provides transmission of error and control messages





between hosts and routers.



Address Resolution Protocol (ARP)



Maps IP addresses to physical addresses.



Transmission Control Protocol (TCP)



Provides reliable data
-
stream delivery service





between end nodes.



User Datagram Protocol (UDP)



Provides unreliable datagram delivery service





between end nodes.



File Transfer Protocol(FTP)



Provides application
-
level services for file transfer.



TELNET



Provides terminal emulation.



Routing Information Protocol (RIP)



Enables the exchange of distance vector routing





information between routers.



Open Shortest Path First (OSPF)



Enables the exchange of link state routing





information between routers.



Exterior Gateway Protocol (EGP)



Enables the exchange of routing information between





exterior routers.




Overview of TCP/IP Protocol Usage



Applications

developed

for

TCP/IP

generally

use

several

of

the

protocols

in

the

suite
.

The

sum

of

the

layers

of

the

protocol

suite

is

also

known

as

the

protocol

stack
.

User

applications

communicate

with

the

top

layer

of

the

protocol

suite
.

The

top
-
level

protocol

layer

on

the

source

computer

passes

information

to

the

lower

layers

of

the

stack,

which

in

turn

pass

it

to

the

physical

network
.

The

physical

network

transfers

the

information

to

the

destination

computer
.

The

lower

layers

of

the

protocol

stack

on

the

destination

computer

pass

the

information

to

higher

layers,

which

in

turn

pass

it

to

the

destination

application
.


Each

protocol

layer

within

the

TCP/IP

suite

has

various

functions
;

these

functions

are

independent

of

the

other

layers


Now

we

will

see

the

TCP/IP

protocol

layers
.


TCP/IP Protocol Layers



An

application

for

transferring

files

with

TCP,

for

instance,

performs

the

following

operations

to

send

the

file

contents
:



The

Application

layer

passes

a

stream

of

bytes

to

the

Transport

layer

on

the

source

computer
.



The Transport layer divides the stream into TCP segments, adds a header with a
sequence number for that segment, and passes the segment to the Internet (IP) layer. A
checksum is computed over the TCP header and data.


The IP layer creates a packet with a data portion containing the TCP segment. The IP
layer adds a packet header containing source and destination IP addresses.


The IP layer also determines the physical address of the destination computer or
intermediate computer on the way to the destination host. It passes the packet and the
physical address to the Data
-
Link layer. A checksum is computed on the IP header.


The Data
-
Link layer transmits the IP packet in the data portion of a data
-
link frame to
the destination computer or an intermediate computer. If the packet is sent to an
intermediate computer, steps 4 through 7 are repeated until the destination computer is
reached.


Contd……..


At the destination computer, the Data
-
Link layer discards the data
-
link header and
passes the IP packet to the IP layer.



The IP layer checks the IP packet header. If the checksum contained in the header
does not match the checksum computed by the IP layer, it discards the packet.



If the checksums match, the IP layer passes the TCP segment to the TCP layer.



The TCP layer computes a checksum for the TCP header and data. If the computed
checksum does not match the checksum transmitted in the header, the TCP layer
discards the segment. If the checksum is correct and the segment is in the correct
sequence, the TCP layer sends an acknowledgment to the source computer and
passes the data to the application.



The application on the destination computer receives a stream of bytes, just as if it
were directly connected to the application on the source computer.






Transport Layer Protocols



The

Transport

layer

of

the

TCP/IP

protocol

suite

consists

of

two

protocols,

UDP

and

TCP
.

UDP

provides

an

unreliable

connectionless

delivery

service

to

send

and

receive

messages
.

TCP

adds

reliable

byte

stream
-
delivery

services

on

top

of

the

IP

datagram

delivery

service
.


Transmission Control Protocol


What

is

TCP?



Transmission

Control

Protocol

(TCP)

provides

a

reliable

byte
-
stream

transfer

service

between

two

endpoints

on

an

internet
.



TCP

depends

on

IP

to

move

packets

around

the

network

on

its

behalf
.

IP

is

inherently

unreliable,

so

TCP

protects

against

data

loss,

data

corruption,

packet

reordering

and

data

duplication

by

adding

checksums

and

sequence

numbers

to

transmitted

data

and,

on

the

receiving

side,

sending

back

packets

that

acknowledge

the

receipt

of

data
.


Before

sending

data

across

the

network,

TCP

establishes

a

connection

with

the

destination

via

an

exchange

of

management

packets
.

The

connection

is

destroyed,

again

via

an

exchange

of

management

packets,

when

the

application

that

was

using

TCP

indicates

that

no

more

data

will

be

transferred
.

In

OSI

terms,

TCP

is

a

Connection
-
Oriented

Acknowledged

Transport

protocol
.



TCP

has

a

multi
-
stage

flow
-
control

mechanism

which

continuously

adjusts

the

sender's

data

rate

in

an

attempt

to

achieve

maximum

data

throughput

while

avoiding

congestion

and

subsequent

packet

losses

in

the

network
.

It

also

attempts

to

make

the

best

use

of

network

resources

by

packing

as

much

data

as

possible

into

a

single

IP

packet
.



Contd
………
.





The

TCP

protocol

uses

full
-
duplex

transmission
.

Full

duplex

means

that

two

data

streams

can

flow

in

opposite

directions

simultaneously
.

Thus,

the

receiving

application

can

send

data

or

control

information

back

to

the

sending

application

while

the

sending

application

continues

to

send

data
.


The

TCP

protocol

gives

each

segment

a

sequence

number
.

At

the

receiving

end

of

the

connection,

TCP

checks

successive

sequence

numbers

to

ensure

that

all

the

segments

are

received

and

processed

in

the

order

of

the

sequence

numbers
.

The

receiving

end

sends

an

acknowledgment

to

the

sender

for

the

segments

received
.

TCP

enables

the

sender

to

have

several

outstanding

segments

before

the

receiver

must

return

an

acknowledgment
.

If

the

sending

node

does

not

receive

an

acknowledgment

for

a

segment

within

a

certain

time,

it

retransmits

that

segment
.

This

scheme,

called

positive

acknowledgment

with

retransmission
,

ensures

that

the

stream

delivery

is

reliable
.


The

TCP

data

unit

is

called

a

segment
;

the

name

is

due

to

the

fact

that

TCP

sends

a

block

of

bytes

from

the

byte

stream

between

sender

and

receiver
.

Now

we

will

see

the

structure

of

the

segment

and

about

the

different

fields

of

the

segments
:



TCP Segment Format.




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|

Source

Port

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Destination

Port

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|

Sequence

Number

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Acknowledgement

Number

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|Offset

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Flags

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Window

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|

Checksum

|

Urgent

Pointer

|


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|

Options
....

(Padding)

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|

Data
...


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Source

Port

and

Destination

Port
:

Identify

the

source

and

destination

ports

to

identify

the

end
-
to
-
end

connection

and

higher
-
layer

application
.


Sequence

Number
:

Contains

the

sequence

number

of

this

segment's

first

data

byte

in

the

overall

connection

byte

stream
;

since

the

sequence

number

refers

to

a

byte

count

rather

than

a

segment

count,

sequence

numbers

in

contiguous

TCP

segments

are

not

numbered

sequentially
.


Acknowledgment

Number
:

Used

by

the

sender

to

acknowledge

receipt

of

data
;

this

field

indicates

the

sequence

number

of

the

next

byte

expected

from

the

receiver
.


Data

Offset
:

Points

to

the

first

data

byte

in

this

segment
;

this

field,

then,

indicates

the

segment

header

length
.





Contd
……
..




Control Flags
:

A set of flags that control certain aspects of the TCP virtual connection. The
flags include:

Urgent Pointer Field Significant (URG)
:

When set, indicates that the current
segment contains urgent (or high
-
priority) data and that the Urgent Pointer field
value is valid.

Acknowledgment Field Significant (ACK)
:

When set, indicates that the value
contained in the Acknowledgment Number field is valid. This bit is usually set,
except during the first message during connection establishment.

Push Function (PSH)
:

Used when the transmitting application wants to force TCP
to immediately transmit the data that is currently buffered without waiting for the
buffer to fill; useful for transmitting small units of data.

Reset Connection (RST)
:

When set, immediately terminates the end
-
to
-
end TCP
connection.

Synchronize Sequence Numbers (SYN)
:

Set in the initial segments used to
establish a connection, indicating that the segments carry the initial sequence
number.

Finish (FIN)
:

Set to request normal termination of the TCP connection in the
direction this segment is traveling; completely closing the connection requires one
FIN segment in each direction.


Contd……...






Window
:

Used for flow control, contains the value of the
receive window size

which
is the number of transmitted bytes that the sender of this segment is willing to accept
from the receiver.


Checksum
:

Provides rudimentary bit error detection for the segment (including the
header and data).


Urgent Pointer
:

Urgent data is information that has been marked as high
-
priority by a
higher layer application; this data, in turn, usually bypasses normal TCP buffering and
is placed in a segment between the header and "normal" data. The Urgent Pointer,
valid when the URG flag is set, indicates the position of the first octet of nonexpedited
data in the segment.


Options
:

Used at connection establishment to negotiate a variety of options; maximum
segment size (MSS) is the most commonly used option.


Internet Protocol

What

is

IP?



Internet

Protocol

(IP)

is

the

central,

unifying

protocol

in

the

TCP/IP

suite
.

It

provides

the

basic

delivery

mechanism

for

packets

of

data

sent

between

all

systems

on

an

internet,

regardless

of

whether

the

systems

are

in

the

same

room

or

on

opposite

sides

of

the

world
.

All

other

protocols

in

the

TCP/IP

suite

depend

on

IP

to

carry

out

the

fundamental

function

of

moving

packets

across

the

internet
.


In

the

TCP/IP

protocol

suite,

all

packets

are

delivered

by

the

IP

datagram

delivery

service
.

Packet

delivery

is

not

guaranteed

by

this

service
.

A

packet

can

be

misdirected,

duplicated,

or

lost

on

the

way

to

its

destination
.

The

service

is

connectionless

because

all

packets

are

transmitted

independently

of

any

other

packets
.



To

keep

track

of

the

delivery

status,

TCP/IP

applications

using

the

IP

datagram

delivery

service

expect

to

receive

replies

from

the

destination

node
.



IP

defines

the

form

that

packets

must

take

and

the

ways

that

packets

are

handled

when

they

are

transmitted

or

received
.

The

form

the

packet

takes

is

called

an

I
P

datagram
.

It

is

the

basic

unit

of

information

that

is

passed

across

a

TCP/IP

network
.

The

IP

datagram

consists

of

a

header

and

a

data

section
.

The

header

section

contains

the

sender's

(source)

IP

address

and

the

receiver's

(destination)

IP

address

and

other

information
.



IP Datagram structure.



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|Version|

IHL

|

TOS

|

Total

Length

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Identification

|Flags|

Fragment

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Header

Checksum

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+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+


|

Source

Address

|


+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+


|

Destination

Address

|


+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+


|

Options
....

(Padding)

|


+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+


|

Data
...


+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-



Version
:

Specifies

the

IP

version

of

the

packet
.

The

current

version

of

IP

is

version

4
,

so

this

field

will

contain

the

binary

value

0100
.

Internet

Header

Length

(IHL)
:

Indicates

the

length

of

the

datagram

header

in

32

bit

(
4

octet)

words
.

A

minimum
-
length

header

is

20

octets,

so

this

field

always

has

a

value

of

at

least

5

(
0101
)
.


Type

of

Service

(TOS)
:

Allows

an

originating

host

to

request

different

classes

of

service

for

packets

it

transmits
.


Total

Length
:

Indicates

the

length

(in

bytes,

or

octets)

of

the

entire

packet,

including

both

header

and

data
.

Given

the

size

of

this

field,

the

maximum

size

of

an

IP

packet

is

64

KB,

or

65
,
535

bytes
.


Identification
:

Used

when

a

packet

is

fragmented

into

smaller

pieces

while

traversing

the

Internet,

this

identifier

is

assigned

by

the

transmitting

host

so

that

different

fragments

arriving

at

the

destination

can

be

associated

with

each

other

for

reassembly
.


Flags
:

Also

used

for

fragmentation

and

reassembly
.

The

first

bit

is

called

the

More

Fragments

(MF)

bit,

and

is

used

to

indicate

the

last

fragment

of

a

packet

so

that

the

receiver

knows

that

the

packet

can

be

reassembled
.

The

second

bit

is

the

Don't

Fragment

(DF)

bit,

which

suppresses

fragmentation
.

The

third

bit

is

unused

(and

always

set

to

0
)
.




Contd
………
.

Fragment

Offset
:

Indicates

the

position

of

this

fragment

in

the

original

packet
.

In

the

first

packet

of

a

fragment

stream,

the

offset

will

be

0
;

in

subsequent

fragments,

this

field

will

indicates

the

offset

in

increments

of

8

bytes
.


Time
-
to
-
Live

(TTL)
:

A

value

from

0

to

255
,

indicating

the

number

of

hops

that

this

packet

is

allowed

to

take

before

discarded

within

the

network
.

Every

router

that

sees

this

packet

will

decrement

the

TTL

value

by

one
;

if

it

gets

to

0
,

the

packet

will

be

discarded
.


Protocol
:

Indicates

the

higher

layer

protocol

contents

of

the

data

carried

in

the

packet
;

options

include

ICMP

(
1
),

TCP

(
6
),

UDP

(
17
),

or

OSPF

(
89
)
.


Header

Checksum
:

Carries

information

to

ensure

that

the

received

IP

header

is

error
-
free
.


Source

Address
:

IP

address

of

the

host

sending

the

packet
.


Destination

Address
:

IP

address

of

the

host

intended

to

receive

the

packet
.


Options
:

A

set

of

options

which

may

be

applied

to

any

given

packet,

such

as

sender
-
specified

source

routing

or

security

indication
.

The

option

list

may

use

up

to

40

bytes

(
10

words),

and

will

be

padded

to

a

word

boundary
.



Physical and IP Addresses


Each

node

has

a

physical

address

for

the

specific

hardware

device

that

connects

it

to

a

network
.



Physical

addresses

are

also

called

media

access

control

(MAC)

addresses
.



The

IP

address

for

a

node

is

a

logical

address

and

is

independent

of

any

particular

hardware

or

network

topology
.

It

has

the

same

form,

regardless

of

the

media

type
.

The

IP

address

is

a

4
-
byte

(
32
-
bit)

numeric

value

that

identifies

both

a

network

and

a

local

host

or

node

(computer

or

other

device)

on

that

network
.

The

4
-
byte

IP

address

is

usually

represented

in

dotted

decimal

notation
.

Each

byte

is

represented

by

a

decimal

number,

and

periods

separate

the

bytes,

for

example,

129
.
47
.
6
.
17
.


Assigning IP Network Addresses


For

a

node

using

the

TCP/IP

protocol

suite

to

communicate

with

other

nodes,

including

nodes

on

other

private

networks

and

on

the

Internet,

an

IP

network

address

is

required
.



If

you

are

accessing

the

Internet

through

an

Internet

Service

Provider

(ISP),

you

can

be

assigned

an

IP

address

by

your

ISP
.



The

addresses

for

all

the

nodes

on

the

network

must

meet

the

following

criteria
:


All

addresses

within

a

network

must

use

the

same

prefix
.

For

example,

any

node

on

network

129
.
47

must

have

an

address

in

the

form

129
.
47
.
x
.
x
.



Each node must have a unique IP address.


The

following

section

describes

how

to

select

an

address

class
.



Historic IP Address Classes


IP

addresses

are

32

bits

in

length

(As

in

Figure

below)
.

They

are

typically

written

as

a

sequence

of

four

numbers,

representing

the

decimal

value

of

each

of

the

address

bytes
.

Since

the

values

are

separated

by

periods,

the

notation

is

referred

to

as

dotted

decimal
.

A

sample

IP

address

is

208
.
162
.
106
.
17
.


IP Address Format:



1

1

1

1

1

1

1

1

1

1

2

2

2

2

2

2

2

2

2

2

3

3


0

1

2

3

4

5

6

7

8

9

0

1

2

3

4

5

6

7

8

9

0

1

2

3

4

5

6

7

8

9

0

1


--
+
-------------
+
------------------------------------------------


Class

A

|
0
|

NET_ID

|

HOST_ID

|


|
-
+
-
+
-----------
+
---------------
+
-------------------------------
|



Class

B

|
1
|
0
|

NET_ID

|

HOST_ID

|


|
-
+
-
+
-
+
-------------------------
+
---------------
+
---------------
|


Class

C

|
1
|
1
|
0
|

NET_ID

|

HOST_ID

|


|
-
+
-
+
-
+
-
+
---------------------------------------
+
---------------
|


Class

D

|
1
|
1
|
1
|
0
|

MULTICAST_ID

|


|
-
+
-
+
-
+
-
+
-------------------------------------------------------
|


Class

E

|
1
|
1
|
1
|
1
|

EXPERIMENTAL_ID

|


--
+
-
+
-
+
-
+
--------------------------------------------------------





IP

addresses

are

hierarchical

for

routing

purposes

and

are

subdivided

into

two

subfields
.

The

Network

Identifier

(NET_ID)

subfield

identifies

the

TCP/IP

subnetwork

connected

to

the

Internet
.

The

NET_ID

is

used

for

high
-
level

routing

between

networks,

much

the

same

way

as

the

country

code,

city

code,

or

area

code

is

used

in

the

telephone

network
.

The

Host

Identifier

(HOST_ID)

subfield

indicates

the

specific

host

within

a

subnetwork
.



To

accommodate

different

size

networks,

IP

defines

several

address

classes
.

Classes

A,

B,

and

C

are

used

for

host

addressing

and

the

only

difference

between

the

classes

is

the

length

of

the

NET_ID

subfield
:


Class

A

address

has

a

7
-
bit

NET_ID

and

24
-
bit

HOST_ID
.

Class

A

addresses

are

intended

for

very

large

networks

and

can

address

up

to

16
,
777
,
216

(
2
24
)

hosts

per

network
.

The

first

digit

of

a

Class

A

addresses

will

be

a

number

between

1

and

126
.

Relatively

few

Class

A

addresses

have

been

assigned
;

examples

include

4
.
0
.
0
.
0

(BBN

Planet)

and

9
.
0
.
0
.
0

(IBM)
.


Class

B

address

has

a

14
-
bit

NET_ID

and

16
-
bit

HOST_ID
.

Class

B

addresses

are

intended

for

moderate

sized

networks

and

can

address

up

to

65
,
536

(
2
16
)

hosts

per

network
.

The

first

digit

of

a

Class

B

address

will

be

a

number

between

128

and

191
.

The

Class

B

address

space

has

long

been

threatened

with

being

used

up

and

it

is

has

been

very

difficult

to

get

a

new

Class

B

address

for

some

time
.

Class

B

address

assignment

examples

include

128
.
138
.
0
.
0

(WestNet)

and

152
.
163
.
0
.
0

(America

Online)
.





Class

C

address

has

a

21
-
bit

NET_ID

and

8
-
bit

HOST_ID
.

These

addresses

are

intended

for

small

networks

and

can

address

only

up

to

254

(
2
8
-
2
)

hosts

per

network
.

The

first

digit

of

a

Class

C

address

will

be

a

number

between

192

and

223
.

Most

addresses

assigned

to

networks

today

are

Class

C

(or

sub
-
Class

C!)
;

examples

include

208
.
162
.
102
.
0

(Hill

Associates)

and

209
.
198
.
87
.
0

(SoverNet,

Bellows

Falls,

VT)
.


The

remaining

two

address

classes

are

used

for

special

functions

only

and

are

not

commonly

assigned

to

individual

hosts
.

Class

D

addresses

may

begin

with

a

value

between

224

and

239
,

and

are

used

for

IP

multicasting

(i
.
e
.
,

sending

a

single

datagram

to

multiple

hosts)
.


Class

E

addresses

begin

with

a

value

between

240

and

255
,

and

are

reserved

for

experimental

use
.




Several

address

values

are

reserved

and/or

have

special

meaning
.

A

HOST_ID

of

0

(as

used

above)

is

a

dummy

value

reserved

as

a

place

holder

when

referring

to

an

entire

subnetwork
;

the

address

208
.
162
.
106
.
0
,

then,

refers

to

the

Class

C

address

with

a

NET_ID

of

208
.
162
.
106
.

A

HOST_ID

of

all

ones

(usually

written

"
255
"

when

referring

to

an

all
-
ones

byte,

but

also

denoted

as

"
-
1
")

is

a

broadcast

address

and

refers

to

all

hosts

on

a

network
.

A

NET_ID

value

of

127

is

used

for

loopback

testing

and

the

specific

host

address

127
.
0
.
0
.
1

refers

to

the

localhost
.






IP version 6

The

official

version

of

IP

that

has

been

in

use

since

the

early

1980
s

is

version

4
.

Due

to

the

tremendous

growth

of

the

Internet

and

new

emerging

applications,

it

was

recognized

that

a

new

version

of

IP

was

becoming

necessary
.

In

late

1995
,

IP

version

6

(IPv
6
)

was

entered

into

the

Internet

Standards

Track
.

IPv
6

is

the

Internet

Engineering

Task

Force's

next
-
generation

Internet

communications

protocol

having

new

features
.

IPv
6

is

designed

as

an

evolution

from

IPv
4
,

rather

than

a

radical

change
.

IPv
6

is

fairly

well

defined

but

is

not

yet

widely

deployed
.

Primary

areas

of

change

relate

to
:




Increasing

the

IP

address

size

to

128

bits





Better

support

for

traffic

types

with

different

quality
-
of
-
service



objectives




Extensions

to

support

authentication,

data

integrity,

and

data



confidentiality








IPv
4

has

address

limitations,

performance

problems

and

a

raft

of

other

deficiencies
.

All

need

to

be

addressed

for

the

Internet

and

related

IP

technologies

to

move

forward

-

especially

in

light

of

the

Internet's

exploding

popularity

and

growing

use

as

a

multimedia

delivery

system
.



As

the

use

of

Internet

and

IP
-
related

technologies

increases,

the

strains

placed

on

IPv
4

become

more

evident
.

Big

companies

are

having

trouble

getting

addresses

for

new

users
.

New

applications

with

multimedia

capabilities

are

being

delayed

or

not

deployed

at

all

because

there

is

no

way

to

prioritize

traffic

flow
.

Administrators

find

it

difficult

to

add,

delete

and

change

accounts

on

large

IP
-
based

networks
.


What are the new features of IPv6 and how they could benefit
corporations and Internet users over the coming years.


Probably the biggest and most talked about new component IPv6 brings to the table
is a larger address space. Addresses define a specific node on the network where
data, such as mail or file transfers should be sent. Most people are familiar with
Internet addresses, such as xyz@nww.com.


Addressing has been the bane of the Internet's existence for years. Most experts
expect the current stockpile of 4.3 billion IPv4
-
based addresses to be eaten up in the
next few years.


IPv6 has a 128
-
bit address space versus IPv4's 32
-
bit space, which will allow for a
geometric increase in the number of possible addresses. This means a far greater
number of users will be able to tie directly into the 'Net. It should also increase the
scalability of IP
-
based networks in the corporate environment.


IPv6 will also divvy up addresses differently. The idea is to reserve groups of
addresses for specific types of use and leave lots of unallocated address space for
future growth. For example, IPv4 devices will keep their existing eight
-
digit
designations, but ISPs will get a three
-
digit code that will remain unique to those
vendors. Other designations will be reserved for local use or deployment by devices
that support advanced functions such as multicast operations.


Contd……..


Addressing isn't the only issue being addressed in IPv6. In order to speed up IPv6
transmissions, the protocol's header has been greatly simplified with unused fields
being made optional. Headers are the part of a transmission that guide data to its
proper destination. With this improved header, data should traverse IP
-
based nets
much more quickly and with less overhead.


Other new components of IPv6 include technology that would prioritize the flow of
IP
-
based traffic over an TCP/IP backbone. Called "flow labeling," the feature would
provide a standard way for workstations or hosts to specify special handling of
certain traffic types. The feature is important for future multimedia or other
applications that generate lots of interactive traffic. For example, an important
videoconference could be labeled to ensure it receives transmission priority over,
say, routing remote file transfers.