Basic ip and networking ver 3 kl
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BASIC IP NETWORKING
Kuala Lumpur January 2011
Azhar Ali
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TCP/IP FUNDAMENTALS
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• 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
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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
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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
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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 ?
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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
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6
5
4
3
2
1
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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
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4 on 7-layer Model
TCP/IP OSI
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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
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• 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
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Data Flow in 4-layer Model
Application
Transport
Internet
Network
Application
Transport
Internet
Network
Internet
Network
‘network’
PHYSICAL PHYSICAL
A C
B
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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
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3
2
1
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Typical Scenario
User Process
User Process
TCP UDP
IP
Datalink and Hardware Layer e.g Ethernet
4
3
2
1
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4 and 7-layer Model Comparison
Reference : http://www.lex-con.com/protocols/ip.htm
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7-layer Map – TCP/IP
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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?
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• 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?
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• 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?
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Addresses in TCP/IP
User Process
User Process
TCP UDP
IP
Datalink and Hardware Layer e.g Ethernet
4
3
2
1
Internet
Address (32
bits)
Port Address
(16 bits)
Physical
Address (48
bits)
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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
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TFTP over Ethernet
TFTP client
UDP
IP
Ethernet
TFTP server
UDP
IP
Ethernet
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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-IP H-ETH T-ETH
TFTP message
UDP segment
IP packet
Ethernet frame
14 20 8 4 200 4 H – Header T – Trailer
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DATAGRAM
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• 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
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• 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)
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Format of IP Datagram H
ead
er
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 15 16 31
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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
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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
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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?
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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.
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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?
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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
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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
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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
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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
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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
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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
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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
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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
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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 Host Subnet
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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
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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
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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
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BASIC
NETWORK
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Common Component in IP Network
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