Agenda 1. QUIZ 2. TEST & LAST WEEK’S QUIZ 3. HOMEWORK 4. SWITCHING 5. POINT-TO-POINT PROTOCOL 6....
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Transcript of Agenda 1. QUIZ 2. TEST & LAST WEEK’S QUIZ 3. HOMEWORK 4. SWITCHING 5. POINT-TO-POINT PROTOCOL 6....
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