“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Local Area Networks

Gerd Keiser

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Chapter Four

LAN Access Techniques

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

General concept of a simple queuing modelFigure 4.1

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Vulnerable period in the pure ALOHA schemeFigure 4.2

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Throughput versus offered load for pure and slotted ALOHAFigure 4.3

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Transmission attempts and random retransmission delays for colliding packets in slotted ALOHAFigure 4.4

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Successful and unsuccessful transmission attempts for nonpersistent CSMAFigure 4.5

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Throughput S as a function of the offered load G Figure 4.6

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Packet arrivals in slotted nonpersistent CSMAFigure 4.7

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Flow diagram for the CSMA/CD protocolFigure 4.8

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Performance comparisonsFigure 4.9

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Throughput as a function of G for 1-persistent CSMA/CDFigure 4.10

Reprinted with permission from Takagi and Kleinrock,17 © 1987, IEEE

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Examples of three types of polling schemesFigure 4.11

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Use of a central LAN switch in a star network architectureFigure 4.12

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

LAN-to-LAN and LAN-to-MAN/WAN switchesFigure 4.13

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

The basic concept of a LAN switchFigure 4.14

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Equilibrium throughput curve in slotted ALOHAFigure 4.15

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Equilibrium contours for slotted ALOHAFigure 4.16

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Example of a channel load lineFigure 4.17

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Example of a globally stable, lightly loaded systemFigure 4.18

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Bistable system: 2 locally stable & 1 unstable equilibrium pointsFigure 4.19

“Local Area Networks” - Gerd Keiser Copyright © 2003 - The McGraw-Hill Companies srl

Behavior of systems which are (a) stable but overloaded (b) unstable with infinite usersFigure 4.20