Flow Control
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Flow Control as PDF for free.
More details
- Words: 673
- Pages: 36
Chapter 11
Data Link Control and Protocols McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.1 Flow and Error Control Flow Control Error Control
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
Note: Flow control refers to a set of procedures used to restrict the amount of data that the sender can send before waiting for acknowledgment.
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
Note: Error control in the data link layer is based on automatic repeat request, which is the retransmission of data.
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.2 Stop-and-Wait ARQ 1.
Sender keeps a copy of the last frame Transmitted Until it receives an acknowledgment for that frame.
4.
Both data frames and ACK frames are numbered alternately 0 & 1
6.
Damaged, out of order or lost frames will be discarded and will not be acknowledged
9.
Control variables: S holds the number of recently sent frame R holds the number of next frame expected
12. Sender starts a timer when it sends a frame 14. Receiver sends only positive ACK
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.1
McGraw-Hill
Normal operation
©The McGraw-Hill Companies, Inc., 2004
11.2
McGraw-Hill
Stop-and-Wait ARQ, lost frame
©The McGraw-Hill Companies, Inc., 2004
11.3
McGraw-Hill
Stop-and-Wait ARQ, lost ACK frame
©The McGraw-Hill Companies, Inc., 2004
Note: In Stop-and-Wait ARQ, numbering frames prevents the retaining of duplicate frames.
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.4
McGraw-Hill
Stop-and-Wait ARQ, delayed ACK
©The McGraw-Hill Companies, Inc., 2004
Note: Numbered acknowledgments are needed if an acknowledgment is delayed and the next frame is lost.
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.5
McGraw-Hill
Piggybacking
©The McGraw-Hill Companies, Inc., 2004
11.3 Go-Back-N ARQ Sequence Number Sender and Receiver Sliding Window Control Variables and Timers Acknowledgment Resending Frames Operation McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.6 Sender sliding window
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.7
McGraw-Hill
Receiver sliding window
©The McGraw-Hill Companies, Inc., 2004
11.8
McGraw-Hill
Control variables
©The McGraw-Hill Companies, Inc., 2004
11.9
McGraw-Hill
Go-Back-N ARQ, normal operation
©The McGraw-Hill Companies, Inc., 2004
11.10
McGraw-Hill
Go-Back-N ARQ, lost frame
©The McGraw-Hill Companies, Inc., 2004
11.11
McGraw-Hill
Go-Back-N ARQ: sender window size
©The McGraw-Hill Companies, Inc., 2004
Note: In Go-Back-N ARQ, the size of the sender window must be less than 2m; the size of the receiver window is always 1.
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.4 Selective-Repeat ARQ Sender and Receiver Windows Operation Sender Window Size Bidirectional Transmission Pipelining
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.12
McGraw-Hill
Selective Repeat ARQ, sender and receiver windows
©The McGraw-Hill Companies, Inc., 2004
11.13
McGraw-Hill
Selective Repeat ARQ, lost frame
©The McGraw-Hill Companies, Inc., 2004
Note: In Selective Repeat ARQ, the size of the sender and receiver window must be at most one-half of 2m.
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.14
McGraw-Hill
Selective Repeat ARQ, sender window size
©The McGraw-Hill Companies, Inc., 2004
11.5 HDLC Configurations and Transfer Modes Frames Frame Format Examples Data Transparency
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.15
McGraw-Hill
NRM
©The McGraw-Hill Companies, Inc., 2004
11.16
McGraw-Hill
ABM
©The McGraw-Hill Companies, Inc., 2004
11.17
McGraw-Hill
HDLC frame
©The McGraw-Hill Companies, Inc., 2004
11.18
McGraw-Hill
HDLC frame types
©The McGraw-Hill Companies, Inc., 2004
11.19
McGraw-Hill
I-frame
©The McGraw-Hill Companies, Inc., 2004
11.20
McGraw-Hill
S-frame control field in HDLC
©The McGraw-Hill Companies, Inc., 2004
11.21
McGraw-Hill
U-frame control field in HDLC
©The McGraw-Hill Companies, Inc., 2004
Table 11.1 U-frame control command and response Command/response
Meaning
SNRM
Set normal response mode
SNRME
Set normal response mode (extended)
SABM
Set asynchronous balanced mode
SABME
Set asynchronous balanced mode (extended)
UP
Unnumbered poll
UI
Unnumbered information
UA
Unnumbered acknowledgment
RD
Request disconnect
DISC
Disconnect
DM
Disconnect mode
RIM
Request information mode
SIM
Set initialization mode
RSET
Reset
XID
Exchange ID
FRMR
Frame reject
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
Note: Bit stuffing is the process of adding one extra 0 whenever there are five consecutive 1s in the data so that the receiver does not mistake the data for a flag.
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.24
McGraw-Hill
Bit stuffing and removal
©The McGraw-Hill Companies, Inc., 2004
Data Link Control and Protocols McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.1 Flow and Error Control Flow Control Error Control
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
Note: Flow control refers to a set of procedures used to restrict the amount of data that the sender can send before waiting for acknowledgment.
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
Note: Error control in the data link layer is based on automatic repeat request, which is the retransmission of data.
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.2 Stop-and-Wait ARQ 1.
Sender keeps a copy of the last frame Transmitted Until it receives an acknowledgment for that frame.
4.
Both data frames and ACK frames are numbered alternately 0 & 1
6.
Damaged, out of order or lost frames will be discarded and will not be acknowledged
9.
Control variables: S holds the number of recently sent frame R holds the number of next frame expected
12. Sender starts a timer when it sends a frame 14. Receiver sends only positive ACK
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.1
McGraw-Hill
Normal operation
©The McGraw-Hill Companies, Inc., 2004
11.2
McGraw-Hill
Stop-and-Wait ARQ, lost frame
©The McGraw-Hill Companies, Inc., 2004
11.3
McGraw-Hill
Stop-and-Wait ARQ, lost ACK frame
©The McGraw-Hill Companies, Inc., 2004
Note: In Stop-and-Wait ARQ, numbering frames prevents the retaining of duplicate frames.
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.4
McGraw-Hill
Stop-and-Wait ARQ, delayed ACK
©The McGraw-Hill Companies, Inc., 2004
Note: Numbered acknowledgments are needed if an acknowledgment is delayed and the next frame is lost.
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.5
McGraw-Hill
Piggybacking
©The McGraw-Hill Companies, Inc., 2004
11.3 Go-Back-N ARQ Sequence Number Sender and Receiver Sliding Window Control Variables and Timers Acknowledgment Resending Frames Operation McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.6 Sender sliding window
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.7
McGraw-Hill
Receiver sliding window
©The McGraw-Hill Companies, Inc., 2004
11.8
McGraw-Hill
Control variables
©The McGraw-Hill Companies, Inc., 2004
11.9
McGraw-Hill
Go-Back-N ARQ, normal operation
©The McGraw-Hill Companies, Inc., 2004
11.10
McGraw-Hill
Go-Back-N ARQ, lost frame
©The McGraw-Hill Companies, Inc., 2004
11.11
McGraw-Hill
Go-Back-N ARQ: sender window size
©The McGraw-Hill Companies, Inc., 2004
Note: In Go-Back-N ARQ, the size of the sender window must be less than 2m; the size of the receiver window is always 1.
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.4 Selective-Repeat ARQ Sender and Receiver Windows Operation Sender Window Size Bidirectional Transmission Pipelining
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.12
McGraw-Hill
Selective Repeat ARQ, sender and receiver windows
©The McGraw-Hill Companies, Inc., 2004
11.13
McGraw-Hill
Selective Repeat ARQ, lost frame
©The McGraw-Hill Companies, Inc., 2004
Note: In Selective Repeat ARQ, the size of the sender and receiver window must be at most one-half of 2m.
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.14
McGraw-Hill
Selective Repeat ARQ, sender window size
©The McGraw-Hill Companies, Inc., 2004
11.5 HDLC Configurations and Transfer Modes Frames Frame Format Examples Data Transparency
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.15
McGraw-Hill
NRM
©The McGraw-Hill Companies, Inc., 2004
11.16
McGraw-Hill
ABM
©The McGraw-Hill Companies, Inc., 2004
11.17
McGraw-Hill
HDLC frame
©The McGraw-Hill Companies, Inc., 2004
11.18
McGraw-Hill
HDLC frame types
©The McGraw-Hill Companies, Inc., 2004
11.19
McGraw-Hill
I-frame
©The McGraw-Hill Companies, Inc., 2004
11.20
McGraw-Hill
S-frame control field in HDLC
©The McGraw-Hill Companies, Inc., 2004
11.21
McGraw-Hill
U-frame control field in HDLC
©The McGraw-Hill Companies, Inc., 2004
Table 11.1 U-frame control command and response Command/response
Meaning
SNRM
Set normal response mode
SNRME
Set normal response mode (extended)
SABM
Set asynchronous balanced mode
SABME
Set asynchronous balanced mode (extended)
UP
Unnumbered poll
UI
Unnumbered information
UA
Unnumbered acknowledgment
RD
Request disconnect
DISC
Disconnect
DM
Disconnect mode
RIM
Request information mode
SIM
Set initialization mode
RSET
Reset
XID
Exchange ID
FRMR
Frame reject
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
Note: Bit stuffing is the process of adding one extra 0 whenever there are five consecutive 1s in the data so that the receiver does not mistake the data for a flag.
McGraw-Hill
©The McGraw-Hill Companies, Inc., 2004
11.24
McGraw-Hill
Bit stuffing and removal
©The McGraw-Hill Companies, Inc., 2004
Related Documents
Flow Control
November 2019 23
Flow Control
June 2020 13
Flow Control Durco Cv
November 2019 7
Flow Control Baru.docx
May 2020 7
Control Ing Screen Flow
June 2020 2