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

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Chapter Four LAN Access Techniques

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl General concept of a simple queuing model Figure 4.1

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Vulnerable period in the pure ALOHA scheme Figure 4.2

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Throughput versus offered load for pure and slotted ALOHA Figure 4.3

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Transmission attempts and random retransmission delays for colliding packets in slotted ALOHA Figure 4.4

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Successful and unsuccessful transmission attempts for nonpersistent CSMA Figure 4.5

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Throughput S as a function of the offered load G Figure 4.6

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Packet arrivals in slotted nonpersistent CSMA Figure 4.7

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Flow diagram for the CSMA/CD protocol Figure 4.8

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Performance comparisons Figure 4.9

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Throughput as a function of G for 1-persistent CSMA/CD Figure 4.10 Reprinted with permission from Takagi and Kleinrock, 17 © 1987, IEEE

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Examples of three types of polling schemes Figure 4.11

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Use of a central LAN switch in a star network architecture Figure 4.12

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl LAN-to-LAN and LAN-to-MAN/WAN switches Figure 4.13

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl The basic concept of a LAN switch Figure 4.14

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Equilibrium throughput curve in slotted ALOHA Figure 4.15

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Equilibrium contours for slotted ALOHA Figure 4.16

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Example of a channel load line Figure 4.17

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Example of a globally stable, lightly loaded system Figure 4.18

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Bistable system: 2 locally stable & 1 unstable equilibrium points Figure 4.19

“Local Area Networks” - Gerd Keiser Copyright © The McGraw-Hill Companies srl Behavior of systems which are (a) stable but overloaded (b) unstable with infinite users Figure 4.20