Basic ip and networking ver 3 kl

11
BASIC IP
NETWORKING
Kuala Lumpur
January 2011
Azhar Ali

33
• TCP/IP is the first set of protocols
used in Internet
• Allows computers to
communicate / share resources
across a network
• Work on TCP/IP started in 1970s
 Funded by US Military
 Advanced Research Project Agency
(ARPA)
 Network protocols of ARPANET were
upgraded
I
N
T
R
O

44
TCP/IP
technology
TCP/IP and the
Internet
 Used as a standard
 To bridge the gap
between non-
compatible platforms
 All computers
connected to the
Internet understands
TCP/IP

55
In 1978, International
Standards Organization (ISO)
proposed a 7-layer reference
model for network Services
and protocols
Network Layering in
TCP/IP 7
6
5
4
3
2
1

66
7
6
5
4
3
2
1
• To provide well-defined
interfaces between adjacent
layers
 A change in one layer does not
affect the other layers
 Interface must remain the same
• Allows a structured
development of network
software
Why Layering ?

77
The 7-layer OSI Model
OSI Model shows how networking
should work- provides a blueprint
for protocols to follow – but it’s
not mandatory
Most protocols do follow OSI
model
OSI model can help learn how
networking works, and how to
troubleshoot network problems
Application
Presentation
Session
Transport
Network
Datalink
Physical
7
6
5
4
3
2
1

88
The TCP/IP Protocol
4-layer Model
De-facto standard – used for
connection to the Internet and
within most networks
Uses a 4 layer model
Covers most of the popular
protocols used daily in network
communications
Application
Transport
Internet
Network

99
4 on 7-layer Model
TCP/IP OSI

1010
7-layer Model Summary
OSI Model
Data Unit Layer Function
Host
Layers
Data
7 Application Network process to application
6 Presentation
Data representation, encryption and
decryption
5 Session Interhost communication
Segments 4 Transport
End-to-end connections and
reliability, flow control
Network
Layers
Packet 3 Network
Path determination and logical
addressing
Frame 2 Data Link Physical addressing
Bit 1 Physical
Media, signal and binary
transmission

1111
• Refers to a family of protocols
• The protocols are built on top
of connectionless technology
TCP/IP Protocol Suite
 Data sent from one node to another
as a sequence of datagrams
 Each datagram sent independently
 The datagrams corresponding to the
same message may follow different
routes
o Variable delay, arrival order at
destination

1212
Data Flow in 4-layer
Model
Application
Transport
Internet
Network
Application
Transport
Internet
Network
Internet
Network
‘network’
PHYSICAL PHYSICAL
A C
B

1313
TCP/IP Family Members
FTP TFTP SMTP SNMP DNS USER
PROCESS ..
TRANSMISSION
CONTROL PROTOCOL
(TCP)
USER DATAGRAM
PROTOCOL
(UDP)
INTERNET
PROTOCOL (IP) ICMP IGMP ARP RARP
Datalink and Hardware Layer
e.g Ethernet
4
3
2
1

1414
Typical Scenario
User
Process
User
Process
TCP UDP
IP
e.g Ethernet
4
3
2
1

1515
4 and 7-layer Model
Comparison
Reference : http://www.lex-con.com/protocols/ip.htm

1717
IP transports datagrams
(packets) from the source node to
the destination node
 Responsible for routing the
packets
 Breaks a packet into smaller
packets, if required
 Unreliable service
o A packet may be lost in transit
o Packets may arrive out of order
o Duplicate packets may be
generated
What does IP do?

1818
• TCP provides a connection-
oriented, reliable service for
sending messages
 Split a message into packets
 Reassemble packets at
destination
 Resend packets that were
lost in transit
• Interface with IP
 Each packet forwarded to IP
for delivery
 Error control is done by TCP
What does TCP do?

1919
• UDP provides a
connectionless, unreliable
service for sending datagrams
(packets)
 Messages small enough to fit in
a packet (e.g., DNS query)
 Simpler (and faster) than TCP
 Never split data into multiple
packets
 Does not care about error
control
• Interface with IP
 Each UDP packet send to IP for
delivery
What does UDP do?

2020
Addresses in TCP/IP
User
Process
User
Process
TCP UDP
IP
e.g Ethernet
4
3
2
1
Internet
Address (32
bits)
Port Address
(16 bits)
Physical
Address (48
bits)

2121
Encapsulation
Basic concept
 As data flows down
the protocol
hierarchy, headers
(and trailers) get
appended to it
 As data moves up
the hierarchy, headers
(and trailers) get
stripped off

2222
TFTP over Ethernet
TFTP client
UDP
IP
Ethernet
TFTP server
UDP
IP
Ethernet

2323
Encapsulation in TFTP
Data
Data
Data
Data
Data
H-TFTP
H-TFTP
H-TFTP
H-TFTP
H-UDP
H-UDP
H-UDP
H-IP
H-IPH-ETH T-ETH
TFTP message
UDP segment
IP packet
Ethernet
frame
14 20 8 4 200 4
H – Header
T – Trailer

2525
• IP layer provides a
connectionless, unreliable
delivery system for packets
…………..….. mentioned before
• Each packet is independent
of one another
 IP layer need not maintain
any history
 Each IP packet must contain
the source and destination
addresses
The
IP
Layer

2626
• IP layer does not guarantee
delivery of packets
• IP layer encapsulation
 Receives a data chunk from
the higher layer (TCP or UDP)
 Prepends a header of
minimum 20 bytes
o Containing relevant information
for handling routing and flow
control
The IP Layer (contd)

2727
Format of IP Datagram
Header
VER HLEN Service
type Total Length
Identification Flags Fragment
Offset
Time to
Live Protocol Header Checksum
Source IP Address
Destination IP Address
Options
DATA
0 4 8 1516 31

2828
IP Header Fields
Fields
No of
bits
Remarks
VER 4 Version of the IP protocol in use (typically 4)
HLEN 4 • Length of the header, expressed as the number
of 32-bit words
• Minimum size is 5, and maximum 15
Total Length 16 • Length in bytes of the datagram, including
headers
• Maximum datagram size : 2 = 65536 bytes
Service Type 8 • Allow packet to be assigned a priority
• Router can use this field to route packets
• Not universally used
Time to Live 8 • Prevents a packet from travelling in a loop
• Senders sets a value, that is decremented at
each hop. If it reaches zero, packet is discarded
Protocol 8 Identifies the higher layer protocol being used
16

2929
IP Header Fields (contd)
Fields
No of
bits
Remarks
Source IP
address
32 Internet address of the sender
Destination IP
address
32 Internet address of the destination
Identification,
Flags, Fragment
Offset
32 Used for handling fragmentation
Options var • Can be given provided router supports
• Source routing, for example
Header
Checksum
16 •Covers only the IP header
•A mismatch in checksum causes the datagram
to be discarded

3131
1. How many bits are there in the IP
address?
2. How many bits are there in the
Ethernet address?
3. What does the Ethernet address
signify?
4. What does the IP address
signify?
5. What does the port number
signify?

3232
6. What the various layers in the
simplified TCP/IP protocol stack
corresponds to with respect to
the OSI 7-layer model?
7. Why is the transport layer called
end-to-end or host-to-host
layer?
8. IP is unreliable, and TCP uses IP.
How does TCP provide reliable
service to the application layer?
9. List two common applications that
use UDP.

3333
10. Why is the IP protocol considered
unreliable?
11. What does TCP do if the
message to be sent is larger than
what a single datagram can
handle?
12. What is the purpose of the ‘Time
to Live’ field in the IP header?
13. What is the maximum size of
data that can be accommodated
in an IP datagram?

3434
Basic IP Addressing
• Each host connected to the
Internet is identified by a
unique IP address
• An IP address is a 32 bit
quantity
 Expressed as dotted-
decimal notation w.x.y.z,
where dots are used to
separate each of the four
octets of the address
 Consists of two logical
parts:
o A network number
o A host number
• The partition defines the IP
address classes

3535
Dotted Decimal Notation
(w.x.y.z)
66.134.48.126
01000010.10001000.00110000.01111110
32 bits
An IP address
for an Internet
site would look
like this

3636
Hierarchical Addressing
A computer on the Internet
is addressed using two
method:
 The network number
o Assigned and managed by
central authority
 The host number
o Assigned and managed by
local network administrator
When routing a
packet to the
Destination, only
the network
number is
looked at

3737
IP Address Classes
There are five defined IP
Address Classes
Class A, B, C, D and E
(reserved) identified by the
first few bits in the IP address
There are also exists some
special-purpose IP addresses

3838
IP Address Classes
The class-based addressing is
also known as the classful
model
 Different network classes
represent different network-
to-hosts ratio
 Lend themselves to different
network configurations

3939
IP Address Classes
Class Network Address
A 10.0.0.0 through 10.255.255.255
B 172.16.0.0 through 172.31.255.255
C 192.168.0.0 through 192.168.255.255
Class
First
Bits
First Byte
Values
Network
ID Bits
Host ID
Bits
Number of
Networks
Number of
Hosts
A 0 1 - 126 7 24 126 16,777,214
B 10 128 -191 14 16 16,384 65,534
C 110 192 - 223 21 8 2,097,152 254
Private IP Address Range – Special purpose

4040
IP Subnetting
• Subset of a class A, B or
C network
• Introduce third level of
hierarchy
 A network portion
 A subnet portion
 A host portion
• Uses network masks

4141
Network Masks
Network mask
255.0.0.0 is applied to a
class A network 10.0.0.0
11111111 00000000 00000000 00000000
In binary, the mask is a
series of contiguous
1’s followed by a series
of contiguous 0’s
Network Host

4242
Network Masks
• Class A network 10.5.0.20
00001010 00000101 00000000 00010100
11111111 11111111 00000000 00000000
10.5.0.20
255.255.0.0
IP Address
Mask
Network HostSubnet

4343
Network Masks
e.g Network mask
of 255.255.255.0
Subnet 255.255.255.X
X
X (in
binary)
No. of
Subnets
No. of
Hosts
128 1000 0000 2 128
192 1100 0000 4 64
224 1110 0000 8 32
240 1111 0000 16 16
248 1111 1000 32 8
252 1111 1100 64 4

4444
Running out of IP
addresses
• Growing demand for IP addresses
 Severe strain on the classful model
 Due to wastage of address space
• Measure taken
 Creative allocation of IP addresses
 Classless Inter-Domain Routing
(CIDR)
o e.g 144.16.192.57/18
 Private IP addresses, and Network
Address Translation (NAT)
 IP v6

4646
1. Change the following IP address
from binary notation to dotted
decimal notation 11000100
10001111 00110000 10000001
2. Find the error if any in the following
IP address: 144.15.256.7
3. Find the class of the following IP
address: 227.15.75.111?
4. Given the network address
135.75.0.0, find the class, the
network id, and the range of the
addresses
5. What do the following IP address
signify: 144.16.255.255

4848
Common Component in
IP Network

Basic ip and networking ver 3 kl

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