Agenda 1. QUIZ 2. TEST & LAST WEEK’S QUIZ 3. HOMEWORK 4. SWITCHING 5. POINT-TO-POINT PROTOCOL 6. INTEGRATED SERVICES DIGITAL NETWORK (ISDN) 7. X FRAME RELAY

Last Week’s Quiz 100 workstations dump 5 messages per second on an Ethernet LAN. Each message has 1000 bytes. Is there a congestion problem? Server Utilization= A X S = 500 X [8 (1000)]/10,000,000 =.4 Is there a congestion problem?

Homework 14-1, 14-11, 14-18, & , 15-6 & , 16-9, 16-10, 16-ll, 16-12, & , 17-3 & , 18-3, 18-6 & 18-11

Chapter 14 Switching

Figure 14-1 Switched Network Direct physical connections with switches I to VII connecting all computers

Figure 14-2 Switching Methods Commonly used

Figure 14-4 A Circuit Switch n not necessarily equal to m

Figure 14-6 Circuit Switching Paths and circuits are separated spacially Nominally it’s instantaneously (Adv?) Nominally it requires a large number of cross connects. Why? Like Telephone system? Uses TDM to achieve switching No crosspoints (Adv) Processing time causes delays (Dadv)

Figure 14-7 Crossbar Switch Electronic microswitches Like mechanical relays?

Figure 14-8 Multistage Switch Combines crossbars

Figure 14-9 Switching Path Multiple paths

Figure TDM with and without a Time Slot Interchange (TSI)

Figure Time Slot Interchange RAM has several memory locations, each the same size as a slot. No more FIFO

Figure TDM Bus Uses microswitches to connect ins & outs to a high speed bus. In & out gates are closed at same time so traffic can burst through.

Figure Time Space Time Switch You can combine to optimize!

Optical Switching Demand for bandwidth growing at compound annual rate of 100% Projections by Lucent is Multiple Protocol Label Switching (MPLS) specifically, Generalized MPLA will be preferred method. Optical switching devices are potentially smaller, faster, cheaper and have lower operating power (note the word potentially). Lucent is betting on doing this with micro-electro-mechinical-systems (MEMS) devices. These are also called silicon micromachines. Their product is called the LambdaRouter. Very large scale integration (VLSI) fabrication techniques are required to make MEMS devices cost effective.

Optical Switching # 10K of ports 1K Data rate 100 Mb1 Gb10 Gb100 Gb Electrical Optical

Figure PSTN Hierarchy

Figure Packet Switching Approaches Book calls packed switching better for data (security not considered)

Figure Datagram Approach Different paths & out-of-sequence arrival times

Figure Switched Virtual Circuit (SVC) Classic connection orientation

Figure Permanent Virtual Circuit (PVC) Less latency problem Better repeatability Easier QC

Figure Path versus Route Table limitation?

Figure Dedicated versus Shared Problem?

Chapter 15 Point-to-Point Protocol

Figure 15-1 Point-to-Point Link Designed as an improvement to the Serial Line Internet Protocol (SLIP). IP Friendly Static?

Figure 15-2 PPP Transition States Classical X.25

Figure 15-3 PPP Layers

Figure 15-4 PPP Frames Broadcast address to avoid address issue? Control code for no control (flow & error)

Figure 15-5 Link Control Protocol (LCP) Packet Encapsulated in a Frame Responsible for: Establishing links Maintaining links Configuring links Terminating links Provides negotiation mechanisms to set options between end users.

Figure 15-6 Password Authentication Protocol Open two stepper

Figure 15-7 PAP Packets

Figure 15-8 Challenge Handshake Authentication Protocol

Figure 15-9 Four Types of CHAP Packets

Figure Internetwork Protocol Control Protocol Packet Encapsulated in PPP Frame

Figure Example

Chapter 16 Integrated Services Digital Network (ISDN)

Figure 16-1 ISDN Services The network may change or process the content of the data No network manipulation

Figure 16-2 Voice Communication over an Analog Telephone Network

Figure 16-3 Voice and Data Communication over an Analog Telephone Network

Figure 16-4 Analog and Digital Services over the Telephone Network

Figure 16-5 IDN

Figure 16-6 ISDN

Figure 16-7 Basic Rate Interface (BRI) Bearer & out of band signaling

Figure 16-8 Primary Rate Interface

Figure 16-9 Functional Grouping

Figure Reference Points

Figure ISDN Layers

Figure Simplified Layers of ISDN Uses Link Access Procedure (LAP) for the D channel

Figure BRI Interfaces

Figure S Interface

Figure Binary /1 Quaternary (2B/1Q) Encoding Uses 4 voltage levels. Is this QPSK?

Chapter 17 X.25

Figure 17-1 X.25 Data Terminal Equipment Data circuit-temrinating Equipment

Figure 17-2 X.25 Layers in Relation to the OSI Layers Link Access Protocol-- Balanced 3

Figure 17-3 Format of a Frame Not Your Daddy’s Frame Relay I frame encapsulates PLP S frame is used for flow and error control U frame sets up and disconnects links

Figure 17-4 Addressing at the Frame Layer

Figure 17-5 Three Phases of the Frame Layer Set Async Bal Mode asks & Unnumbered acknowledges

Figure 17-6 Frame Layer and Packet Layer Domains Connection orientation at the packet layer: Est, Xfer, Term

Figure 17-7 Three Virtual Circuits in X.25

Figure 17-8 Logical Channel Numbers in X.25

Chapter 18 Frame Relay

Figure 18-1 Frame Relay versus Pure Mesh T-Line Network Frame Relay uses Virtual Circuit technology to provide less expensive connectivity.

Figure 18-2 Fixed-Rate versus Bursty Data

Figure 18-3 X.25 Traffic

Figure 18-4 Frame Relay Traffic

Comparison of X.25 & Frame Relay FeatureX.25Frame Relay Connection EstablishmentAt Network LayerNone Hop-by-hop error controlAt DL LayerNone Hop-by-hop flow controlAt DL LayerNone End-to-end error controlAt Network LayerNone End-to-end flow controlAt Network LayerNone Data RateFixedBursty MultiplexingAt Network LayerAt DL Layer Congestion ControlNot necessaryNecessary

Figure 18-5 Frame Relay Network Force Fit?

Figure 18-6 Data Link Connection Identifiers

Figure 18-7 PVC DLCIs

Figure 18-8 SVC Setup and Release

Figure 18-9 SVC DLCIs

Figure Comparing Layers in Frame Relay and X.25

Figure Frame Relay Frame