Cara Menggugurkan Sperma Yang Masuk Rahim Biyar Tidak Hamil
Data link layer
1. ARASU ENGINEERING COLLEGE
07-07-2020 1
DEPARTMENT OF COMPUTER SCIENCE & ENGINEERING
STTP on COMPUTER NETWORKS
Day – 2: Data Link Layer Protocols & MAC
Presentation by
Mr. V. KOVENDAN M.E.,
Asst. Professor/CSE
Arasu Engineering College,
Kumbakonam
2. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
DATA LINK LAYER
• Overview
• Properties
• Functions & Services
• Protocols
• MAC
• Demo-on simple LAN Network
07-07-2020 2
ARASU ENGINEERING COLLEGE / CSE
4. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE07-07-2020 4
7. Application Layer
6. Presentation Layer
5. Session Layer
4. Transport Layer
3. Network Layer
2. Data Link Layer
1. Physical Layer
The OSI reference Model, the 7 Layers are
User Supported
Layer
Network
Supported Layer
Transport
Supported Layer
ARASU ENGINEERING COLLEGE / CSE
6. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
Basic Terminologies
Frame PDU (Protocol Data Unit) A PDU at the DLL called Frame
Node A node is a device on a network
Media
The media are the physical means used
to carry data signals
Network
A Network is two are more devices
connected to a common medium
07-07-2020 6
ARASU ENGINEERING COLLEGE / CSE
7. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
DLL Overview
• Provides a well-defined service interface to the
network layer.
• Determines how the bits of the physical layer are
grouped into frames (Framing).
• Deals with transmission errors (CRC).
• Flow control: Regulates the flow of frames.
• Performs general link layer management.
07-07-2020 7
ARASU ENGINEERING COLLEGE / CSE
8. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
Data link layer has two sub-layers:
– Logical Link Control: It deals with protocols,
flow-control, and error control
– Media Access Control: It deals with actual
control of media
07-07-2020 8
Data Link Layer
MAC
LLC
ARASU ENGINEERING COLLEGE / CSE
9. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
Properties of DLL
• Primarily Link Layer implemented in the software
• The link layer is implemented in a network adapter,
also sometimes known as a Network Interface Card
(NIC).
• A NIC controls the wired and wireless connections of a
computer to exchange information with other computers
and the Internet.
• This software Data Layer implementations may be
embedded in physical devices such as switches and
network adapters (firmware)
07-07-2020 9
ARASU ENGINEERING COLLEGE / CSE
11. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
Functionality of DLL
• Data link layer does many tasks on behalf of upper layer. They are:
1. Framing: Data-link layer takes packets from Network Layer and
encapsulates them into Frames.
– Then, it sends each frame bit-by-bit on the hardware.
– At receiver’ end, data link layer picks up signals from hardware and
assembles them into frames.
07-07-2020 11
Relationship between the frames and packets
Packet
Header Payload field Trailer
Packet
Header Payload field Trailer
Frame
Host
A
Host
B
ARASU ENGINEERING COLLEGE / CSE
12. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
Functionality of DLL
07-07-2020 12
802.11 Wireless
Frame
PPP Frame
HDLC
HDLC
Frame Relay
Ethernet Frame
Ethernet Frame
High Level Data Link Control with
acknowledged data transfer
Frame relay is a packet-switching telecommunication service
designed for cost-efficient data transmission for intermittent traffic
between local area networks (LANs) and between endpoints in
wide area networks (WANs).
DLL protocol data unit and uses the
underlying Ethernet physical layer
transport mechanisms.(E-Payload)
ARASU ENGINEERING COLLEGE / CSE
13. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
2. Addressing
Hardware address(Physical address)
3. Synchronization
Machines at both end
4. Error Control
Mechanisms: 1. ACK/NAK 2. Time-out 3. Sequence numbers
5. Flow control
Nodes in different speed controls flow in same speed
6. Multi Access
CSMA/CD (Host transfer – link get collision)
07-07-2020 13
ARASU ENGINEERING COLLEGE / CSE
14. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
• SDLC (Synchronous Data Link Protocol)
– IBM [used to connect remote device to mainframe] (P-to-P) (P-to-M)
• HDLC (High-level Data Link Control)
– Based on SDLC [ provides best effort reliable and unreliable services]
• SLIP (Serial Line Interface Protocol)
– Used to transmit IP packets with dialup service [lack of error detection and correction]
• PPP (Point-to-Point Protocol)
– Same as SLIP but more robust can transport not only IP and other packet types
• Asynchronous Transfer Mode is like Ethernet
– Aimed at WAN and LAN, ATM integrated both the data and voice.
• LAP (Link Access Procedure) Three varieties LAP, LAP Balanced- P-to-P on X.25 Pkt Switched N/W
– LAP D-channel provides service on ISDN, LAP-F frame mode (provides frame Relay n/w)
• LLC (Logical Link Control) IEEE defines in 802.x family of Standard
07-07-2020 14
Data Link Protocols
ARASU ENGINEERING COLLEGE / CSE
15. Data link
Protocol
Transmission
line to a router
C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
Placement of DLL Protocols
07-07-2020 15
2 3 2 2 3
Data Link
Layer Process
Routing Process
Frames Packets
2
Router
ARASU ENGINEERING COLLEGE / CSE
17. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
Error Detection and Correction
Types of Errors
There may be three types of errors:
– Single bit error
• (Frame corrupted with single bit)
– Multiple bits error
• (Frame with more than one bit corrupted)
– Burst error
• (Frame corrupted with more than one consecutive bit)
07-07-2020 17
ARASU ENGINEERING COLLEGE / CSE
18. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
Error Detection and Correction
• Error control mechanism may involve two possible ways:
– Error Detection & Error correction
– Errors in the received frames are detected by means of
• Parity Check
• Cyclic Redundancy Check (CRC).
In both cases, few extra bits are sent along with actual data to confirm that bits
received at other end are same as they were sent. If the counter-check at
receiver’ end fails, the bits are considered corrupted.
07-07-2020 18
ARASU ENGINEERING COLLEGE / CSE
19. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
• Parity Check: One extra bit is sent along with the original bits to make number of
1s either even in case of even parity, or odd in case of odd parity.
• Cyclic Redundancy Check (CRC):
– Binary division
– Codeword (Actual data bits plus the remainder is called a codeword)
07-07-2020 19
ARASU ENGINEERING COLLEGE / CSE
21. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
Error Correction
07-07-2020 21
• Error correction can be done in two ways:
– Backward Error Correction
– Forward Error Correction
Eg: we take ASCII words (7 bits data),
For
m data bits, r redundant bits are used.
r bits can provide 2r of information.,
i.e. m+r+1.
ARASU ENGINEERING COLLEGE / CSE
22. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
Flow Control
07-07-2020 22
• Stop and Wait
• Sliding Window
• Stop and Wait
– Forces sender after sends a frame to stop
and wait until ACK is received
Most commonly used protocols to
control the flow of data
ARASU ENGINEERING COLLEGE / CSE
24. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE07-07-2020 24
• Duplex mode
• Error prone channel
• Allows multiple frames
• Receiver has the buffer W called (window size)
• ACK includes no. of frame expected
Sliding Window Protocol
6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5
Window
ARASU ENGINEERING COLLEGE / CSE
25. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE07-07-2020 25
Sliding Window Protocol
• Sender Sliding Window
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6
Direction Direction
This wall moves to the right,
frame by frame, when a
frame is sent.
This wall moves to the right, the size
of several frames at a time, when an
ACK is received.
Sender Window
ARASU ENGINEERING COLLEGE / CSE
26. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE07-07-2020 26
Sliding Window Protocol
• Receiver Sliding Window
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6
Direction Direction
This wall moves to the right,
frame by frame, when a
frame is received.
This wall moves to the right, the size
of several frames at a time, when an
ACK is sent.
Receiver Window
ARASU ENGINEERING COLLEGE / CSE
28. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE07-07-2020 28
Error Control
• Requirements for error control mechanism:
– Error detection
– Positive ACK
– Negative ACK
– Retransmission (sender maintain clock and Set timeout)
• There are three types to control the errors by
Automatic Repeat Requests (ARQ):
– Stop-and-wait ARQ
– Go-Back-N ARQ
– Selective Repeat ARQ
ARASU ENGINEERING COLLEGE / CSE
29. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE07-07-2020 29
Error Control
• Stop-and-wait ARQ
– Cases of operations:
1. Normal operation
2. Frame lost
3. ACK lost
4. ACK delay
ARASU ENGINEERING COLLEGE / CSE
30. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE07-07-2020 30
Error Control
• Stop-and-wait ARQ (Normal operation)
ACK 0
ACK 1
Frame 0
Frame 1
Sender Receiver
S=0
S=1
S=0
R=0
R=1
Time Time
ARASU ENGINEERING COLLEGE / CSE
31. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE07-07-2020 31
• Stop-and-wait ARQ (Frame lost)
Lost
ACK 1
Frame 0
Frame 1
Sender Receiver
S=0
S=1
S=0
R=0
R=1
Time Time
R=1
R=0
S=1
Time out
ARASU ENGINEERING COLLEGE / CSE
32. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE07-07-2020 32
• Stop-and-wait ARQ (ACK lost)
ACK Lost
ACK 1
Frame 0
Frame 1
Sender Receiver
S=0
S=1
S=0
R=0
R=1
Time Time
R=1
R=0
S=1
Time out
ARASU ENGINEERING COLLEGE / CSE
35. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
Selective Repeat ARQ
07-07-2020 35
• Go-Back-N is inefficient of a noisy link. (Higher probability of damage) makes
resending is complex in bandwidth which slow down the transmission rate.
• Solution: Selective Repeat ARQ: It resends only the damaged frames. Before timer
expires
• Processing at receiver end is complex.
Sender Receiver
ARASU ENGINEERING COLLEGE / CSE
36. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
LINK-LAYER ADDRESSING
07-07-2020 36
• Link-layer protocols define three types of addresses:
– Unicast
– Multicast
– Broadcast
• Unicast Address
– One to one communication
– Eg.: phone call
• Multicast Address
– one-to-many communication.
– Eg.: e-mail message to a mailing list.
• Teleconferencing and videoconferencing
• Broadcast Address
– one-to-all communication.
– Eg.: digital TV subscribers
ARASU ENGINEERING COLLEGE / CSE
37. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
Address Resolution Protocols:
07-07-2020 37
• The actual communication happens over the physical address. (MAC Address)
• Mission is to get the destination MAC address.
• ARP functionality is to translate IP address to physical address.
• Position of ARP in TCP/IP suite
ARASU ENGINEERING COLLEGE / CSE
39. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
Media Access Control
07-07-2020 39
• To transfer the data we need some address
• Network provides various addressing types.
• Media Access Control Address ( physical address)
• MAC Addresses are unique 48-bits
• IEEE 802 standard, Data Link Layer is divided into two sublayers
– 1. Logical Link Control(LLC) Sublayer
– 2. Media Access Control(MAC) Sublayer
• MAC address is used by Media Access Control (MAC) sublayer of Data-Link Layer.
• Word wide unique address.
• 12-digit hexadecimal number (6-Byte binary number)
• First 6-digits (say 00:40:96) represents OUI
• OUI of well known manufacturers:
– CC:46:D6 - Cisco
– 3C:5A:B4 - Google
– Inc. 3C:D9:2B - Hewlett Packard
ARASU ENGINEERING COLLEGE / CSE
41. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE07-07-2020 41
• MAC address can be represented using any of the following
formats
• Hyphen-Hexadecimal notation
• E4-E7-49-61-DF-74
• Colon-Hexadecimal notation
• E4:E7:49:61:DF:74
• Period-Separated-Hexadecimal notation
• E4.E7.49.61.DF.74
ARASU ENGINEERING COLLEGE / CSE
42. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE07-07-2020 42
• How to find MAC address
– Command for UNIX/Linux: ifconfig -a
ip link list
ip address show
– Command for Windows OS:
ipconfig /all
- Command for MacOS:
TCP/IP Control Panel
ARASU ENGINEERING COLLEGE / CSE
46. C
O
M
P
U
T
E
R
N
E
T
w
O
R
K
S
Mr. V. KOVENDAN AP/ CSE, ARASU ENGINEERING COLLEGE
Demonstration of simple network module on
how to connect Devices
(Hub, Switch, Router) with a simple LAN….
07-07-2020 46
ARASU ENGINEERING COLLEGE / CSE