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.25 8. 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, 14-51 & 14-52

15-2, 15-6 & 15-9

16-2, 16-9, 16-10, 16-ll, 16-12, 16-13 & 16-14

17-1, 17-3 & 17-9

18-1, 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 separatedspacially

Nominally it’s instantaneously (Adv?)Nominally it requires a large number

of cross connects. Why?Like Telephone system?

Uses TDM to achieveswitching

No crosspoints (Adv)Processing time causes

delays (Dadv)

Figure 14-7

Crossbar Switch

Electronic microswitchesLike mechanical relays?

Figure 14-8

Multistage Switch

Combines crossbars

Figure 14-9

Switching Path

Multiple paths

Figure 14-10

TDM with and without a Time Slot Interchange (TSI)

Figure 14-11

Time Slot Interchange

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

Figure 14-12TDM Bus

Uses microswitchesto connect ins & outsto a high speed bus.

In & out gates are closed at same timeso traffic can burstthrough.

Figure 14-13

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

ofports 1K

100

10

Data rate

100 Mb 1 Gb 10 Gb 100 Gb

Electrical

Optical

Figure 14-14

PSTN Hierarchy

Figure 14-16

Packet Switching Approaches

Book calls packed switching better for data (security not considered)

Figure 14-17

Datagram Approach

Different paths & out-of-sequence arrival times

Figure 14-19

Switched Virtual Circuit (SVC)

Classic connection orientation

Figure 14-20

Permanent Virtual Circuit (PVC)

Less latency problemBetter repeatabilityEasier QC

Figure 14-21

Path versus Route

Table limitation?

Figure 14-22

Dedicated versus Shared

Problem?

Chapter 15

Point-to-PointProtocol

Figure 15-1

Point-to-Point Link

Designed as an improvement to the Serial Line Internet Protocol (SLIP).

IP FriendlyStatic?

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 linksMaintaining linksConfiguring linksTerminating 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 15-10

Internetwork Protocol Control Protocol Packet Encapsulated in PPP Frame

Figure 15-11

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 16-10

Reference Points

Figure 16-11

ISDN Layers

Figure 16-12 Simplified Layers of ISDN

Uses Link Access Procedure (LAP) for the D channel

Figure 16-13

BRI Interfaces

Figure 16-14

S Interface

Figure 16-15

2 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 FrameNot Your Daddy’s Frame Relay

I frame encapsulates PLPS frame is used for flow and error controlU 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

FrameRelay

Figure 18-1

Frame Relay versus Pure Mesh T-Line Network

Frame Relay uses Virtual Circuit technology to provide lessexpensive 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

Feature X.25 Frame RelayConnection Establishment At Network Layer NoneHop-by-hop error control At DL Layer NoneHop-by-hop flow control At DL Layer NoneEnd-to-end error control At Network Layer NoneEnd-to-end flow control At Network Layer NoneData Rate Fixed BurstyMultiplexing At Network Layer At DL LayerCongestion Control Not necessary Necessary

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 18-13

Comparing Layers in Frame Relay and X.25

Figure 18-14

Frame Relay Frame