Download Window size = 3 Send 2

CCNA
Cisco Certified Network Associate
640-802
” ‫قال تعالي ” و قل رب زدني علما‬
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Mohammedsn
OSI 7 layer
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OSI Open System Interconnection
We want the system to be standard to can
any one use it
 ISO International Standard Organization
Make standarization to main task for
operation ( IEEE)

OSI Model Overview
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Application
Application
(Upper)
Layers
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Presentation
Session
Transport Layer
Network Layer
Data Link
Data Flow
Layers
Physical
3
7- Application
Layer
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HTTP : Browsing protocol
 FTP : File Transfer Protocol
 TFTP : Trivial FTP
 Telnet : Remote access protocol
 SMTP : Simple Mail Transfer protocol
 SNMP : Simple Network Management
Protocol

6- presentation layer
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Format of data
 Compression & decompression of data
 Encoding & decoding of data

Such ac ASCII code ( 8bit) , EBCDIC code
(5bit)
5- session layer
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Set a logical connection ( session)
between different application
 Specifies communication mode
( simple - Half duplex – full duplex )

4- Transport layer
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
Flow control

Error recovery
Flow control
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Pc1
Pc2
Buffering
Congestion avoidence
stop
Go on
Windowing
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Sender
Receiver
Windowing
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Sender
Window size = 3
Send 1
Window size = 3
Send 2
Window size = 3
Send 3
Receiver
Windowing
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Sender
Window size = 3
Send 1
Receiver
Window size = 3
Send 2
Window size = 3
Send 3
ACK 3
Window size = 2
Packet 3 is
Dropped
Windowing
Sender
Window size = 3
Send 1
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Receiver
Window size = 3
Send 2
Window size = 3
Send 3
Window size = 3
Send 3
Window size = 3
Send 4
ACK 3
Window size = 2
Packet 3 is
Dropped
Windowing
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Sender
Window size = 3
Send 1
Receiver
Window size = 3
Send 2
Window size = 3
Send 3
Packet 3 is
ACK 3
Window size = 2 Dropped
Window size = 3
Send 3
Window size = 3
Send 4
ACK 5
Window size = 2
TCP Sequence and
Acknowledgment Numbers
Source
Port
Dest.
Port
Sequence
#
Acknowledgement
#
…
I just
sent #10.
Source Dest. Seq. Ack.
1028
23
10
1
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Mohammedsn
TCP Sequence and
Acknowledgment Numbers
Source
Port
Dest.
Port
Sequence
#
I just
sent #10.
Acknowledgement
#
…
I just got #10,
now I need #11.
Source Dest. Seq. Ack.
1028
23
10
1
Source Dest. Seq. Ack.
23
1028
1
11
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Mohammedsn
TCP Sequence and
Acknowledgment Numbers
Source
Port
Dest.
Port
I just
sent #11.
Sequence
#
Acknowledgement
#
…
I just got #10,
now I need #11.
Source Dest. Seq. Ack.
1028
23
10
1
Source Dest. Seq. Ack.
23
1028
1
11
Source Dest. Seq. Ack.
1028
23
11
2
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Mohammedsn
TCP Sequence and
Acknowledgment Numbers
Source
Port
Dest.
Port
I just
sent #11.
Sequence
#
Acknowledgement
#
…
I just got #11,
now I need #12
Source Dest. Seq. Ack.
1028
23
10
1
Source Dest. Seq. Ack.
23
1028
1
11
Source Dest. Seq. Ack.
1028
23
11
2
Source Dest. Seq. Ack.
23
1028
2
12
Type of protocol at transport layer

TCP (connection oriented protocol)
It must establish session before transmit the
data , make recovery&control
 UDP connectionless protocol no
session,no recovery&no control
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3-Network layer
1-routing
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2-IP addressing
2- Data link

1- Arbitration : find the best time to send
the data ( CSMA/CD & taken)
Error detection
1- parity check : but very week
2-CRC : Depend on mathematical equation

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Data link is divided into two sub
layer

802.3 MAC sub layer ( Media Access
control)

802.2 LLC sub layer ( Logical Link Control)
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MAC address : hardware address
48 bit
24 bit ( vendor)
24 bit IEEE
LLC sub layer
TCP/IP
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SPX/IPX
Physical Layer:
Ethernet/802.3
10Base2—Thin Ethernet
10Base5—Thick Ethernet
Host
Hub
10BaseT—Twisted Pair
Hosts
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Encapsulating Data
Application
Presentation
Session
Upper Layer Data
TCP Header
Transport
Upper Layer Data
IP Header
Data
LLC Header
Data
FCS
MAC Header
Data
FCS
0101110101001000010
PDU
Segment
Network
Packet
Data Link
Frame
Physical
Bits
De-encapsulating Data
Application
Presentation
Session
Upper Layer Data
Transport
Upper Layer Data
Network
TCP+ Upper Layer Data
IP + TCP + Upper Layer Data
Data Link
LLC Hdr + IP + TCP + Upper Layer Data
Physical
0101110101001000010
Network Device Domains
Hub
Bridge
Switch
Router
Collision Domains:
1
4
Broadcast Domains:
1
1
4
4
1
4
Hubs Operate at Physical layer
Physical
ffff.ffff.ffff
A
B
C
D
• All devices in the same collision domain
• All devices in the same broadcast domain
• Devices share the same bandwidth
Switches and Bridges Operate
at Data Link Layer
Data Link
1
2
3
4
OR
1
2
• Each segment has its own collision domain
• All segments are in the same broadcast domain
Router Operate at Network layer
255.255.255.255
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Question
Mohammedsn
Broadcast
??
A
B
C
collision ??
D
A
B
C
D
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Question
Mohammedsn
Broadcast
??
A
B
C
collision ??
D
A
B
C
D
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Question
Mohammedsn
Broadcast
??
A
B
C
collision ??
D
A
B
C
D
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Question
Mohammedsn
Broadcast
??
C
B
collision ??
A
C
B
A
Hubs: One Collision Domain
• More end stations means
more collisions
• CSMA/CD is used
Switches
Switch
Memory
• Each segment has its
own collision domain
• Broadcasts are
forwarded to all
segments