05 – Internet Protocol

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Transcript 05 – Internet Protocol

Internet Protocol
BS IT 4th Semester
By: Muhammad Hanif
Goals….

Many people fail in life, not for lack of ability
or brains or even courage but simply
because they have never organized their
energies around a goal.
‐ Elbert Hubbard

It's how you deal with failure that
determines how you achieve success.
‐ David Feherty
Network layer in an internetwork
Network Layer

Source
◦ Creating a packet from the Segments.
 The header contains source and destination IP addresses.
◦ Checking the routing table to find the path.
◦ If the packet is larger than MTU, fragment it.

Router
◦ Routing the packet by consulting the routing table
for each incoming packet and find the path that the
packet must be sent to.

Destination
◦ Address verification.
◦ Removing the Packets header from the packets and
pass it to Transport layer.
IPV4
The Internet Protocol version 4 (IPv4) is the delivery
mechanism used by the TCP/IP protocols.
Position of IPv4 in TCP/IP protocol
suite
IPv4 datagram format
IPv4 Header
Variable length: 20-60 byte
 Contains routing information

IPv4 Format
Version (4-bit): currently 4.
 Header length (4-bit): the length of the IP header in 4-byte unit.
 Type of Services(TOS):

◦ This field was not used earlier because of the lack of standard

Total length
◦ to defines the total length of the datagram including the header in
bytes.
◦ 16-bit number, the maximum IP size is limited to 216 bytes, or 64
Kbytes.
IPv4 Format

Identification
◦ A source node gives a unique ID to each packet.

Time to Live (TTL)
◦ A packet has a limited lifetime in the network to
avoid deadly packets.
◦ Designed to hold a timestamp, and decreased by
each router. A packet is discarded by a router if
TTL is zero.

Protocol
◦ What other protocols are in payload
IPv4 Format

Header checksum
◦ The checksum is use for error correction.
Source IP address and Destination IP
address
 Options

◦ For new protocols

Padding
◦ To make the header a multiple of 32-bit words
Fragmentation



A IP packet can travel through many different networks
using different Layer 2 (Data Link layers).
The source node has no idea of the path and data link
layer its packets will travel.
MTU
◦ Each Data Link layer has its own frame format and limitation.
◦ One of such limitation is the maximum size of the frame, which is
imposed by software, hardware, performance, and standards.
MTUs for some networks
Fragmentation of IP
The source node usually does not fragment the
packet. Instead, Layer 4 will segment the data into
a size that can fit into Layer 3 and Layer 2 of the
source.
 But, there is a possibility that a packet travel
through a link whose MTU is smaller than one of
the source node.

◦ Then, the packet must be fragmented to go forward the
next hop.
◦ Each fragment has its own header mostly repeated from
the original packet.
◦ A fragmented packet can be further fragmented into
even smaller packet.
◦ Fragmented packets will be re-assembled at the final
destination.
Fields for Fragmentation

Identification
◦ The source host generates the unique ID

Flags (3-bits)
◦ Unused bit
◦ DF bit (Don’t Fragment)
 1 – force the router not to fragment the packet. If the packet length is
greater than the MTU, the router will discard the packet and send an
error message to the source
◦ MF bit (More Fragment)
 1 – tell the destination whether or not more fragments follow

Offset
◦ Unit of 8-byte
◦ Allows a receiver to determine the place of a particular
fragment in the original IP datagram, measured in units
of 8-byte blocks.
Header Checksum
Used for error checking of the header.
 At each hop, the checksum of the header is
compared to the value of this field. If a
header checksum is found to be
mismatched, the packet is discarded.

IP Addresses:
Classful Addressing
BS IT 4th Semester
By: Muhammad Hanif
Remember …..

“The more you understand the
less you have to remember.”
Craig A. McCraw

“Develop a passion for learning. If
you do, you’ll never cease to
grow.”
Anthony J. D’Angelo
Addressing
IP Addresses:
Classful Addressing
Lecture overview
IPv4 (IP version 4) Addressing
 For efficient routing, IP addresses are
organized in Networks

◦ Classful addressing
◦ Subnetting
◦ Classless addressing
IP addressing basics
The Internet is used to “move” data from
host to host
 All devices connected to the Internet must
have a globally unique IP address

◦ No two devices can have the same public IP address
◦ This address can be permanent or temporary

IPv4 addresses are 32 bits (= 4 octets) long
◦ This gives 2^32 ~ 4.29 billion addresses
Notation

IPv4 addresses can be written using
the following notation
◦ Binary
◦ Dotted Decimal
◦ Hexadecimal
Binary and Decimal
Exercise
120.120.1.98
 11111110. 10011010. 00110110.
00000101

Solution
120.120.1.98
 11111110. 10011010. 00110110.
00000101
 01111000 .01111000 .00000001.
01100010
 254.154.54.5

Classful addressing

IP addresses were divided into 5
classes: A,B,C,D and E
◦ This is the original scheme known as classful
addressing
◦ From mid‐90’s, classless addressing is introduced
◦ However, classful addressing is still used
Finding the class in binary notation
Exercises
1. Find the class of these IP addresses:
◦ a) 11000001 10000011 00011011 11111111
◦ b) 10000001 10000011 00011011 11111111
2. How many class B addresses are there
altogether?
3. What is the range of class B addresses?
Answer this by giving the first and last class
B addresses in dotted decimal notation.
Solution
1.
a) First 3 bits are 110 ‐> Class C.
b) First 2 bits are 10 ‐> Class B.
2. Class B addresses: the first two bits are
10 then followed by 30 bits of 1/0
2^30 addresses
 3.The first and last class B addresses in
binary are:
◦ 10000000 00000000 00000000 00000000
◦ 10111111 11111111 11111111 11111111

In dotted decimal notation, they are:
◦ 128.0.0.0 and 191.255.255.255
Finding the class in decimal notation
NetID and HostID

IP addresses in classes A,B and C are
divided into Netid and Hostid
◦ Netid: Identifying the network
◦ Hostid: Identifying a host within the network

Hosts within a network
◦ Have the same netid
◦ But different hostid
NetID and HostID
Classes and blocks
Classes and blocks

Class A is divided into 128 blocks
◦
◦
◦
◦

Each block has a different netid
1st block: 0.0.0.0 to 0.255.255.255 (netid = 0)
2nd block: 1.0.0.0 to 1.255.255.255 (netid = 1)
Last block: 127.0.0.0 to 127.255.255.255 (netid = 127)
Network address: the first address of the block
Blocks in class A
Blocks in class B
Blocks in class C
Use of addresses

Classes A, B and C addresses can be
assigned to hosts, router ports etc
◦ They are also known as unicast addresses

Class D addresses are for multicast
◦ Multicast: One sender, multiple recipients

Class E addresses are reserved for
special purposes
Network addresses
The network address is the first address in
the block
 The network address defines the network
to the rest of the Internet

◦ Routers route packets based on network address

Given the network address, we can find the
class of the address and the range of the
address in the block
IP Version 6 (IPv6)
BS IT 4th Semester
By: Muhammad Hanif
Challenges in Life….



Sharks and Fish
The Japanese have always loved fresh fish.
But the waters close to Japan have not
held many fish for decades.
So to feed the Japanese population, Fishing
boats got bigger and went farther than
ever.The farther the fishermen went, the
longer it took to bring in the fish. If the
return trip took more than a few days, the
fish were not fresh.The Japanese did not
like the taste.
To solve this problem: …………………..
Challenges in Life…

Sharks and Fish………..

To keep the fish tasting fresh, the Japanese fishing companies still put the
fish in the tanks.
But now they add a small shark to each tank. The shark eats a few fish, but
most of the fish arrive in a very lively state. The fish are challenged.

Have you realized that some of us are also living in a pond but most
of the time tired & dull, So we need a Shark in our life to keep us
awake and moving?

Basically in our lives Sharks are new challenges to keep us active
and lively. Some times blessings come in disguise!
Agenda
Why IPv6?
 IPv6 History
 IPv6 Addressing
 IPv6 Datagram
 Transition from IPv4 to IPv6

Motivations for IPv6
IPv4 addresses are running out
 IPv4 addresses are not enough
 Encryption and authentication not provided
by IPv4

Conception of IPv6

Internet Protocol version 6 (RFC)
◦ Over 200 related RFCs
 IPv6 -RFC 2460
 IPv6 Neighbor Discovery –RFC 2461
 IPv6 Auto Configuration –RFC 2462
A new type of IP address
 A new type of IP packet

What Happened to IPv5?
0
IP
1
IP
2
IP
3
IP
4
IPv4
5
ST
6
IPv6
7
CATNIP
8
Pip
9
TUBA
10‐15







March 1977 version
January 1978 version
February 1978 version A
February 1978 version B
September 1981 version
Stream Transport
December 1998 version
IPng evaluation
IPng evaluation
IPng evaluation
unassigned
(deprecated)
(deprecated)
(deprecated)
(deprecated)
(current widespread)
(not a new IP, little use)
(formerly SIP, SIPP)
(formerly TP/IX; deprecated)
(deprecated)
(deprecated)
SIP = Simple Internet Protocol
SIPP = Simple Internet Protocol Plus
CATNIP = Common Address Technology for Next‐Generation IP ,
TP/IX = RFC 1475
Pip = Paul’s IP? RFC 1621
TUBA = TCP and UDP with Bigger Addresses , RFC 1347
Deprecated = Express strong disapproval
What happened to IPv5
Version 5 in IP header was assigned to
Streaming Protocol.
 Experimental non-IP real-time streaming
protocol.
 Never widely used
 RFC 1819

Features of IPv6
Expanded address space: 128‐bit
address (32‐bit for IPv4)
 Support for

◦
◦
◦
◦
Real‐time service
Mobile IP
Security
Note: Most of these services are added onto
IPv4 but IPv6 must support them
IPv6 addressing

128 bits means you can have 2^128
addresses, which is
340,282,366,920,938,463,463,374,607,
431,768,211,456 = 340 trillion trillion
trillion addresses
◦ This is approximately 3.4 x 10^38
◦ Compare with 4 x 10^9 IPv4 addresses, IPv6 has
10^29 times more Addresses
◦ 67 billion billion addresses per cm2 of the
planet surface
IPv6 address format
2001:0DA8:E800:0000:0260:3EFF:FE47:0001

8 groups of 4 hexadecimal digits
◦ Each group represents 16 bits
◦ Separator is “:”
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IPv6 address format
2001:0DA8:E800:0000:0260:3EFF:FE47:0001
2001:DA8:E800:0:260:3EFF:FE47:1
2001:0DA8:E800:0000:0000:0000:0000:0001
2001:DA8:E800::1
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IP Datagram
IPv4 Header
Header: from IPv4 to IPv6
Changed
Removed
IPv6 Header Format
IPv6 header

IPv6 header is simpler than IPv4
◦ IPv4: 14 fields, variable length (20 bytes +)
◦ IPv6: 8 fields, fixed length (40 bytes)

Header fields eliminated in IPv6
◦
◦
◦
◦
◦

Header Length
Identification
Flag
Fragmentation Offset
Checksum
Header fields enhanced in IPv6
◦ Traffic Class
◦ Flow Label
IP V6 Header
Version –4 bits –Identifies the version of
IP protocol
 0100 (4) for IPv4
 0110 (6) for IPv6

IP V6 Header
Traffic Class –8 bits –Allows originating
nodes and/or routers to distinguish
between different classes or priorities of
IPv6 packets
 QoS is an example implementation

IP V6 Header
Flow Label –20 bits –Used to “label” a
flow of traffic.
 RFC 1809 “Using the Flow Label Field in
IPv6”

IP V6 Header
Payload Length –16 bits –Length, in
octets, of the payload
 Payload = 65536 bytes

IP V6 Header
Next Header –8 bits – Identifies the type
of header immediately following the IPv6
header;
 Identifies the “extension” header
immediately following
 Packet may have zero, one, or more
extension headers

IP V6 Header

Hop Limit –8 bits –Maximum number of
hops IPv6 packet can be forwarded.
◦ Similar to IPv4 TTL.
IP V6 Header

Source Address –128-bits
◦ versus IPv4 32-bit

Destination Address –128-bits
◦ versus IPv4 32-bit
Tunnelling Mechanisms

How they work:
◦ Encapsulation of IPv6 packets within IPv4 packets
and vice versa
◦ The tunnel's end point performs the necessary
operations on the protocol:
 Reconnection of fragmented packets
 Packet forwarding in the IPv6 network
◦ Nodes performing the encapsulation and
decapsulation operation have to be dual stack
Transition Mechanisms

Dual Stacks
◦ IPv4/IPv6 coexistence on one device

Tunnels
◦ For tunneling IPv6 across IPv4 clouds
◦ Later, for tunneling IPv4 across IPv6 clouds
◦ IPv6 <‐> IPv6 and IPv4 <‐> IPv4

Translators
◦ IPv6 <‐> IPv4
IPv6 transition

IPv6 tunnel over IPv4
IPv4
Network
IPv6
IPv6
tunnel
IPv4 Header
IPv6 Header Data
IPv6 Header Data
IPv6 Header Data
Tunneling

IPv6 packets goes through IPv4 network

IPv4 packets goes through IPv6 network
Thank you 