Presentation On
Computer’s Network
Topic:-Framing & it’s methods
Group members:Anuj Panday
Chander kishore
Framing

Frames Are The Small data Units
Created By Data Link Layer And
The Process Of Creating Frames
By The Data Link Layer Is Known
As Framing.
Framing Method Implemented By
Data Link Layer Are:



Character Count.
Starting & Ending Characters With
Character Stuffing.
Starting & ending Flags With Bit
Stuffing.
Physical Layer Coding Violation.
Character Count.


This Method Specifies The Number
Of Characters That Are Present In
particular Frame.
This Information Is specified By
using a Special Field In the Header
Frame.
Character count
3 0 1 4 1 7 5 7 2 0 1 4 2 6 2 1
Frame 1
Frame 2
Frame 3
Character Count Method
Frame 4
Starting & Ending Characters
With Character Stuffing.


In this Method Frame Starts & End With a
special Character That Mark The Beginning &
End Of Frame.
Each character Begins With the ASCII
Character Sequence DLE STX (data link
Escape Start Of Text ) And End With ASCII
Character Sequence DLE ETX (data link escape
End Of text)
Starting & Ending Characters
With Character Stuffing.
A
B
C
DLE STX
Start Of Frame
D
A
Data From Network Layer
B
Data
C
D
DLE ETX
End Of Frame
Starting & Ending Characters Added By Link Layer
Character Stuffing.
A
B DLE C
D
data on
Sender side
DLE STX A B DLE DLE C D DLE ETX
Start Of Frame
Data
A
B DLE C
End Of Frame
D
data on
Reciever side
Starting & ending Flags With
Bit Stuffing.




In this Method , Each Begins & Ends With a
Special Bit pattern 01111110 Called Flags.
There for Each frame starts With 01111110&
also Ends with 01111110.
The Main Problem arises in this Method When
The Flag byte 01111110 Appear as data.
This Problem Is Handled By technique called Bit
stuffing That Is similar To character stuffing.
Starting & ending Flags With
Bit Stuffing.
01111110
0101 0011111 0 101
01111110
Ending Flag BIT
Starting flag Bit
Stuffing
Performed
By Data
Link layer
Shifted Bit
0101 001111110101
BIT stuffing
Data received by
Network layer On
reciever side After
Performing
Destuffing By data
link Layer
Physical Layer Coding Violation.



This Framing Method Is Used only In
those network In which Encoding On The
Physical Medium Contain some
Redundancy.
Some LANs Encode Each Bit Of Data By
using two Physical Bit
i.e.
Menchester coding is Used.
In this method Bit 1 Is encoded into highlow(10) Pair And Bit 0 Is Encoded Into
low-high(01)pair shown in figure.
Physical Layer Coding Violation.
0
1
0
1
1
Menchester Encoding
0
Thank you
House Is open
for Queries.