07- DataLinkControlProto

07- DataLinkControlProto - William Stallings Data and...

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
William Stallings Data and Computer Communications 8 th Edition Chapter 7 Data Link Control Protocols
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Flow Control Ensuring the sending entity does not overwhelm  the receiving entity Preventing buffer overflow Transmission time Time taken to emit all bits into medium Propagation time Time for a bit to traverse the link
Background image of page 2
Model of Frame Transmission
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Stop and Wait Source transmits frame Destination receives frame and replies with  acknowledgement Source waits for ACK before sending next frame Destination can stop flow by not send ACK Works well for a few large frames
Background image of page 4
Fragmentation Large block of data may be split into small  frames Limited buffer size Errors detected sooner (when whole frame received) On error, retransmission of smaller frames is needed Prevents one station occupying medium for long  periods Stop and wait becomes inadequate
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Stop and Wait Link Utilization
Background image of page 6
Sliding Windows Flow Control Allow multiple frames to be in transit Receiver has buffer W long Transmitter can send up to W frames without  ACK Each frame is numbered ACK includes number of next frame expected Sequence number bounded by size of field (k) Frames are numbered modulo 2 k
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Sliding Window Diagram
Background image of page 8
Example Sliding Window
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Sliding Window Enhancements Receiver can acknowledge frames without  permitting further transmission (Receive Not  Ready) Must send a normal acknowledge to resume If duplex, use piggybacking If no data to send, use acknowledgement frame If data but no acknowledgement to send, send last  acknowledgement number again, or have ACK valid  flag (TCP)
Background image of page 10
Error Detection Additional bits added by transmitter for error  detection code Parity Value of parity bit is such that character has even  (even parity) or odd (odd parity) number of ones Even number of bit errors goes undetected
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
For a block of  k  bits transmitter generates  n  bit  sequence Transmit  k+n
Background image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/10/2012 for the course CSC 411 taught by Professor Simmons during the Spring '08 term at S. Alabama.

Page1 / 43

07- DataLinkControlProto - William Stallings Data and...

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online