advanced data communications udhay prakash part 1
TRANSCRIPT
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
1/69
Advanced
Data Communications
Udhay Prakash
uday3prakash@gmail[dot]com
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
2/69
Content for discussion
Data Communication Networks
Protocols & Standards
Standardizing Organizations
2
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
3/69
Data Communication
Can we imagine life without Communication? Why
Factors necessitating data Communication
Local/Remote Sharing/transmission of information
Telecommunication-Distant communication
Data = information+ redundancy
Data is represented by binary information units (bits)
3
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
4/69
Data Communication
Exchange of data (in the form of 0s & 1s) between twodevices via some form of transmission medium.
Communicating entities must be part of communication
System.
Effectiveness of data transmission depends on: Delivery to onlydesired destination(s)
Accuracy -error-freeness
Timeliness- more real-time, lesser the delay should be maintained
4
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
5/69
Components
of Data Communication System
5
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
6/69
Transmission modes-
Simplex, Half-duplex & Full Duplex
6
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
7/69
Data Transmission
7
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
8/69
Data Transmission-
Parallel transmission
8
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
9/69
Data Transmission-
Serial transmission
9
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
10/69
AsynchronousTransmission
10
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
11/69
SynchronousTransmission
11
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
12/69
Networks-
Channel
Set of devices/nodes connected by media links communication channels
Links connecting the devices
12
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
13/69
Networks-
Point to point links
13
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
14/69
Networks-
Multi-point links
14
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
15/69
NetworkTopology
15
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
16/69
Network Topology
Mesh
16
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
17/69
Network Topology-
Bus
17
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
18/69
Network Topology-
Ring
18
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
19/69
Network Topology-
Star
19
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
20/69
Categoryof Networks
20
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
21/69
Categoryof Networks-
LAN
21
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
22/69
Categoryof Networks-
LAN
22
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
23/69
Categoryof Networks-
MAN
23
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
24/69
Categoryof Networks-
WAN
24
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
25/69
Internet
25
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
26/69
Networks-
Distributed Processing
All tasks are divided among multiple entities/nodes.
Advantages
Security/encapsulation
limiting the kinds of interactions that a given user can have on entiresystem
Network (crash) security Distributed databases
No one system needs to store entire data of database. Ex: WWW
Faster problem solving
Multiple computers work on part of total problem
Security through redundancy
Multiple computers running same program at the same time
Collaborative Processing
26
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
27/69
Networks-
Network Criteria
Includes
Performance
No. of users
Type of transmission medium
Hardware
Software Reliability
Frequency of failure
Recovery time after failure
catastrophe
Security Unauthorized access
Malicious software
27
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
28/69
OSIModel
Necessity
The model
Functions of the layers
E l
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
29/69
Assume Maria and Ann are neighbors with a lot of commonideas. However, Maria speaks only Spanish, and Ann speaksonly English. Since both have learned the sign language in theirchildhood, they enjoy meeting in a cafe a couple of days perweek and exchange their ideas using signs. Occasionally, theyalso use a bilingual dictionary. Communication is face to faceand Happens in one layer as shown in Figure below.
Example
29
E l 2 2
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
30/69
Now assume that Ann has to move to another town because ofher job. Before she moves, the two meet for the last time in thesame cafe. Although both are sad, Maria surprises Ann whenshe opens a packet that contains two small machines. The firstmachine can scan and transform a letter in English to a secretcode or vice versa. The other machine can scan and translate aletter in Spanish to the same secret code or vice versa. Anntakes the first machine; Maria keeps the second one. The twofriends can still communicate using the secret code, as shownin Figure below.
Example 2.2
30
E l
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
31/69
Example
31
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
32/69
32
2-2 THE OSI MODEL
Established in 1947, the International StandardsOrganization ISO)is a multinational body dedicatedto worldwide agreement on international standards.Almost three-fourths of countries in the world arerepresented in the ISO. An ISO standard that coversall aspects of network communications is the OpenSystems Interconnection (OSI) model. It was firstintroduced in the late 1970s.
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
33/69
OSI MODEL
33
International Standards Organization (ISO)
Covers all aspects of network communications
Open Systems Interconnection (OSI) model.
ISO is the organ izat ion;
OSI is the model.
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
34/69
OSI Model
34
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
35/69
OSI Model
35
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
36/69
OSI Model
36
An Exchange Using the OSI Model
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
37/69
An Exchange Using the OSI Model
37
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
38/69
Physical Layer
38
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
39/69
Data Link Layer
39
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
40/69
Data Link Layer Example
40
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
41/69
Network Layer
41
T i Di d i h S i
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
42/69
Topics Discussed in the Section
Comparison between OSI and TCP/IP
Layers in the TCP/IP Suite
42
Figure 2.7 Layers in the TCP/I P Protocol Suite
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
43/69
43
Figure 2.7 Layers in the TCP/I P Protocol Suite
Figure 2.8 TCP/I P and OSI model
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
44/69
44
Figure 2.8 TCP/I P and OSI model
Figure 2.9 A private internet
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
45/69
45
g p
Figure 2.10 Communication at the physical layer
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
46/69
46
g p y y
A
Physicallayer
Physicallayer
R1 R3 R4 B
Source DestinationLegend
011 ... 101
011
...101
011 ... 101 011 ... 101
Link 3 Link 5 Link 6Link 1
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
47/69
47
The uni t of commun icat ion at thephys ical layer is a b it .
Note
Figure 2.11 Communication at the data link layer
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
48/69
48
g y
A
Physical Physical
Data linkData link
R1 R3 R4 B
Source Destination DataD Header HLegend
Link 1 Link 3 Link 5 Link 6
FrameD2 H2
Frame
D
2H2
Frame
D2 H2Frame
D2 H2
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
49/69
49
The un i t of commun icat ion at the datal ink layer is a frame.
Note
Figure 2.12 Communication at the network layer
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
50/69
50
A
Physical Physical
Data linkata link
R1 R3 R4 B
NetworkNetwork
Source Destination DataD Header HLegend
Datagram
D3 H3
Datagram
D3 H3
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
51/69
51
The uni t of commun icat ion at thenetwork layer is a datag ram.
Note
Figure 2.13 Communication at transport layer
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
52/69
52
A
Physical Physical
Data linkData link
R1 R3 R4
B
NetworkNetwork
Transport Transport
Source Destination DataD Header HLegend
Segment
D4 H4
Segment
D4 H4
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
53/69
53
The uni t of commun icat ion at thetranspo rt layer is a segment, user
datagram , or a packet, depending on the
speci f ic p roto co l used in th is layer.
Note
Figure 2.14 Communication at application layer
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
54/69
54
A
Physical Physical
Data linkData link
R1 R3 R4
B
NetworkNetwork
Transport Transport
ApplicationApplication Source Destination DataD Header HLegend
MessageD5 D5
D5 D5
Message
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
55/69
55
The uni t of commun icat ion at theappl icat ion layer is a message.
Note
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
56/69
56
2-4 ADDRESSING
Four levels of addresses are used in an internetemploying the TCP/IP protocols: physical address,logical address, port address, and application-specific address. Each address is related to a onelayer in the TCP/IP architecture, as shown in Figure2.15.
Topics Discussed in the Section
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
57/69
57
Topics Discussed in the Section
Physical Addresses
Logical Addresses
Port Addresses
Application-Specific Addresses
Figure 2.15 Addresses in the TCP/I P protocol sui te
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
58/69
58
Example 2.3
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
59/69
59
In Figure 2.16 a node with physical address 10 sends a frame to anode with physical address 87. The two nodes are connected by alink a LAN). At the data link layer, this frame contains physical link)addresses in the header. These are the only addresses needed. Therest of the header contains other information needed at this level. Asthe figure shows, the computer with physical address 10 is thesender, and the computer with physical address 87 is the receiver.The data link layer at the sender receives data from an upper layer. Itencapsulates the data in a frame. The frame is propagated throughthe LAN. Each station with a physical address other than 87 drops theframe because the destination address in the frame does not matchits own physical address. The intended destination computer,however, finds a match between the destination address in the frameand its own physical address.
p
Figure 2.16 Example 2.3: physical addresses
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
60/69
60
Data87 10 1 packet
accepted Data87 10
4
Example 2.4
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
61/69
61
As we will see in Chapter 3, most local area networks use a 48-bit 6-byte) physical address written as 12 hexadecimal digits;every byte 2 hexadecimal digits) is separated by a colon, asshown below:
p
07:01:02:01:2C:4B
A 6-byte (12 hexadecimal digits) physical address
Example 2.5
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
62/69
62
Figure 2.17 shows a part of an internet with two routers connectingthree LANs. Each device computer or router) has a pair of addresseslogical and physical) for each connection. In this case, eachcomputer is connected to only one link and therefore has only onepair of addresses. Each router, however, is connected to threenetworks. So each router has three pairs of addresses, one for eachconnection. Although it may be obvious that each router must have a
separate physical address for each connection, it may not be obviouswhy it needs a logical address for each connection. The computerwith logical address A and physical address 10 needs to send apacket to the computer with logical address P and physical address95. We use letters to show the logical addresses and numbers forphysical addresses, but note that both are actually numbers.
p
Figure 2.17 Example 2.5: logical addresses
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
63/69
63
DataA P20 10 DataA P20 10
Physicaladdresses
changed
DataA P33 99
DataA P33 99
Physicaladdresseschanged
DataA P95 66 DataA P95 66
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
64/69
64
The physical add resses w i ll change fromhop to hop , bu t the log ical add resses
remain the same.
Note
Example 2.6
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
65/69
65
Figure 2.18 shows two computers communicating via theInternet. The sending computer is running three processes atthis time with port addresses a, b, and c. The receivingcomputer is running two processes at this time with portaddresses j and k. Process a in the sending computer needs tocommunicate with process j in the receiving computer. Note thatalthough both computers are using the same application, FTP,for example, the port addresses are different because one is aclient program and the other is a server program.
Figure 2.18 Example 2.6: port numbers
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
66/69
66
A Sender Receiver P
Internet
a DatajA PH2
a DatajA P
a Dataj
Data
a DatajA PH2
a DatajA P
a Dataj
Data
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
67/69
67
The physical add resses change fromhop to hop , bu t the logical and po rt
add resses usual ly remain the same.
Note
Example 2.7
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
68/69
68
As we will see in future chapters, a port address is a 16-bitaddress represented by one decimal number as shown.
753A 16-bit port address represented as one single number
-
8/13/2019 Advanced Data Communications Udhay Prakash Part 1
69/69
Reference
Behrouz A. Forouzan, Sophia Chung Fegan, Data
Communications and Networking, ISBN 978-0-07-325032-8.
Behrouz A. Forouzan, Sophia Chung Fegan, TCP/IP: Protocol
Suite, ISBN 978-0-256-24166-2.