final ppt in cn
DESCRIPTION
data link controlTRANSCRIPT
Data Link Control
Data Link Layer ProtocolsCategories:– Noiseless channels– Noisy channels
Data Link Layer Protocols• Noiseless channels– No requirement for error control (no noise, no
errors)
• Noisy channels– Requires error control
Noiseless Channel Protocols• Simplest Protocol– No flow control
• Stop and wait
Noiseless Simplest Protocol• No noise, so no error control required
• No flow control is required
The design of the simplest protocol with no flow or error control
1.Data Link Layer sender•Get the data from the Network Layer•Make the Data Link Layer Frame•Send the Frame to the Physical Layer
2.Data Link Layer Receiver•Receive the frame from the Physical Layer•Extract the data from the Frame•Deliver the data to the Network Layer
11.9
Flow diagram
Noiseless Stop & Wait Protocol• This protocol includes flow control.• Includes an acknowledgement frame.• No error control.
11.11
Design of Stop-and-Wait Protocol
Stop & Wait: Sender Side•Get the data from the Network layer•Make the Frame•Send Frame to the Physical Layer•Wait for an acknowledgement before sending the next frame
Stop & Wait: Receiver•Receive Frame from the Physical Layer•Extract data from the frame.•Deliver data to the Network Layer•Send an acknowledgement frame back to the sender.
11.13
Flow diagram
Noisy Channel Protocols• Stop & Wait ARQ <- start here• Go Back N ARQ• Selective Repeat ARQ
Stop & Wait ARQ Protocol• Stop & Wait ARQ– ARQ = automatic repeat request
• This protocol has flow control and error control.
Frame Sequence Numbers• The frames are numbered as the current
frame and the next frame. • Only one bit is required to number the frames.
Zero and one are the only frame numbers.
Design of the Stop-and-Wait ARQ Protocol
Flow diagram for Example
PipeliningWhat is the efficiency if fifteen 1000 bit frames
can be sent before waiting for an acknowledgement?
The efficiency is 75%.
THANK YOU