basic data networks
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July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 1
Switch - Basic Data Switch - Basic Data NetworksNetworks
(S-BDN)(S-BDN)
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 2
S-BDNS-BDN
© Copyright 2001 Global Wireless Education Consortium
All rights reserved. This module, comprising presentation slides with notes, exercises, projects and Instructor Guide, may not be duplicated in any way without the express written permission of the Global Wireless Education Consortium. The information contained herein is for the personal use of the reader and may not be incorporated in any commercial training materials or for-profit education programs, books, databases, or any kind of software without the written permission of the Global Wireless Education Consortium. Making copies of this module, or any portion, for any purpose other than your own, is a violation of United States copyright laws.
Trademarked names appear throughout this module. All trademarked names have been used with the permission of their owners.
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 3
S-BDNS-BDN
Partial support for this curriculum material was provided by the National Science Foundation's Course, Curriculum, and Laboratory Improvement Program under grant DUE-9972380 and Advanced Technological Education Program under grant DUE‑9950039.
GWEC EDUCATION PARTNERS: This material is subject to the legal License Agreement signed by your institution. Please refer to this License Agreement for restrictions of use.
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 4
Table of ContentsTable of Contents
Overview 5
Learning Objectives 6
Data Networks 7
Backbone Networks 17
Error Detection And Correction 50
Summary 61
Contributors 62
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 5
OverviewOverview
In this module, you will learn about local area networks, access networks, and backbone networks.
Layered protocols, packet structure, addressing, and error detection and correction within the Public Switched Telephone Network are also discussed.
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 6
Learning ObjectivesLearning Objectives
After completing this module, you will be able to: Compare and contrast the alternative topologies of
networks made up of hubs, routers, switches and gateways that exist in the basic Public Switched Telephone Network (PSTN).
Explain how errors are detected and how to correct them.
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 7
Data NetworksData Networks
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 8
Bandwidth
Narrowband0 - 64 Kbps
Wideband64 Kbps - 45 Mbps
Broadband45 Mbps and Beyond
X.25 Frame Relay ATMSMDS
Token Ring
x xT-1,PRI
T- 3
SONET
LAN
Backbone
Network Access
IP
Ethernet
Network Hierarchy and Network Hierarchy and ProtocolsProtocols
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 9
Topology Definition:
The physical and logical way thenetwork elements are connected
Network TopologyNetwork Topology
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 10
Legend
Device on LAN=
Bus Star Ring
Local Area Network (LAN) Local Area Network (LAN) TopologiesTopologies
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 11
Legend
Device on LAN=
BusExample: Ethernet
CSMA/CD: Carrier Sense Multiple Access/Collision Detection
Sends Data Units out unless you
detect another data unit. already in progress on the bus.
Bus TopologyBus Topology
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 12
RingExample: Token Ring
Send data units when youpossess the token..
Token: Special Type of Data Unit
Ring TopologyRing Topology
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 13
IEEE 802.1 INTERNETWORKING
lOG
ICA
LL
INK
CO
NT
RO
(LL
C)
OSILAYERS3-7
OSILAYER 2
OSILAYER 1
PH
YS
ICA
L
ME
DIU
MA
CC
ES
SC
ON
TR
OL
(MA
C)
IEEE 802.2TYPE 1 - UNACKNOWLEDGED CONNECTIONLESS SERVICETYPE 2 - CONNECTION MODE SERVICETYPE 3 - ACKNOWLEDGED CONNECTIONLESS SERVICE
802.3CSMA/CD(ETHERNET)
802.4TOKEN BUS
802.5 TOKEN RING
802.6DQDB(MAN)
BASEBANDCOAXIALAND UNSHIELDEDTWISTED PAIR
BROADBANDCOAXIAL
BROADBANDCOAXIAL
OPTICALFIBER
SHIELDED OR UNSHIELDEDTWISTED PAIR
OPTICALFIBERORCOAXIALCABLE
LAN StandardsLAN Standards
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 14
Entry to Wide Area Network (WAN)
CustomerPremises
[Bridge-]Router
Access NetworkEnter via port on LAN router
Access NetworksAccess Networks
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 15
Protocol LayersInvolvedin DataTransfer
3
2
1
Switch A Switch CX.25 Network
Switch B
Data Flow in an X.25 Data Flow in an X.25 NetworkNetwork
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 16
Frame Relay Network
Protocol LayersInvolvedin DataTransfer
3
2
1
Switch A Switch CSwitch B
Data Flow in a Frame Data Flow in a Frame Relay NetworkRelay Network
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 17
Backbone Backbone NetworksNetworks
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 18
ATM Cell StructureATM Cell Structure
Header Payload
48 Octets5 Octets
Backbone Example: Backbone Example: Asynchronous Transfer Asynchronous Transfer Mode (ATM)Mode (ATM)
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 19
ATM users receive as much ATM users receive as much bandwidth as they requirebandwidth as they require
Python with expandableskin (bandwidth)
Asynchronous Transfer Asynchronous Transfer Mode (ATM)Mode (ATM)
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 20
User 1
User 2
User 3
125 sec 250 sec 375 sec 500 sec
Asynchronous means data units (cells) areplaced on the network as the application requires
User 1 User 1 User 1
User 2 User 2User 2
User 3
Bandwidth on DemandBandwidth on Demand
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 21
Open Systems Open Systems Interconnection (OSI) ModelInterconnection (OSI) Model
Application
Presentation
Session
Transport
Network
Data Link
Physical
Application
Presentation
Session
Transport
Network
Data Link
Physical
Network
Data Link Data Link
NetworkNode
77
66
55
44
33
22
11
77
66
55
44
33
22
11
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 22
Wireless OSI ModelWireless OSI Model
Application
Presentation
Session
Transport
Network
Data Link
Physical
Application
Presentation
Session
Transport
Network
Data Link
Physical
Network
Data Link Data Link
NetworkNode
77
66
55
44
33
22
11
77
66
55
44
33
22
11
MESSAGES USE
BOTTOM 3 LAYERS
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 23
OSI Protocol “Stack”
What are We Doing?7
Are We Speaking the Same Language (Code)?6
How Long Can Both Sides Talk?
How do We Control Info Flows andand Keep Messages in the Right Order?
5
4
How do We Put Together and Move Chunks of InformationAcross a Whole Network?
3
What Signals and Timing Are We Using?How Are We Going to Recognize Errors between Two Points?2
What Hardware Are We Using?1
The OSI Seven-Layer The OSI Seven-Layer ModelModel
(E-Mail)?
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 24
The OSI Model
Application
Presentation
Session
Transport
Network
Data Link
Physical Header
User Info
1
7
6
5
4
3
2
A Set of RulesA Set of Rules
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 25
Layer 1 DetailsLayer 1 Details
Network
Data Link
Physical
Application
Presentation
Session
Transport
Transmits bits received from the Data Link Layer across the transmission medium
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 26
Layer 2 DetailsLayer 2 Details
Data Link
Physical
Sequences messages and checks for errors between adjacent link stations
Transmits bits received from the Data Link Layer across the transmission medium
Network
Application
Presentation
Session
Transport
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 27
Layer 3 DetailsLayer 3 Details
Network
Data Link
Physical
Fragments or “packetizes” messages and routes them to the proper destination
Sequences messages and checks for errors between adjacent link stations
Transmits bits received from the Data Link Layer across the transmission medium
Application
Presentation
Session
Transport
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 28
Layer 4 DetailsLayer 4 Details
Network
Data Link
Physical
Transport
Fragments or “packetizes” messages and routes them to the proper destination
Sequences messages and checks for errors between adjacent link stations
Transmits bits received from the Data Link Layer across the transmission medium
Provides multiplexing, network connection management, quality of service, etc.
Application
Presentation
Session
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 29
Header Information
Packet FormatPacket Format
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 30
Header User data Perhaps a trailer Store and forward
Packet Switched Packet Switched RoutingRouting
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 31
Header Information
Packet Format
Layer 2 Info Layer 3-5 Info Layer 2 InfoFlag Flag
Message Format
Types of Protocol Data UnitBeing Sent Through a Packet Switched Network
Protocol Data UnitsProtocol Data Units
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 32
Header TrailerUser Data
Protocol Data UnitProtocol Data Unit
Routing Fields
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 33
ROUTERNODE B
DATAC CDATAB C
NODE A NODE C
Destination NodeWon’t Change
Address of NextNode on Route
The router stores packet, reads the destination information and forwards it
to the next node
Routers Routing PacketsRouters Routing Packets
Final Path
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 34
ROUTINGCONSIDERATION
WHAT’S INCLUDED
Performance Number of hops Cost Delay Throughput
Decision Time Packet (Datagram) Session (Virtual Circuit)
Decision Place Each node (Distributed) Central node (Centralized) Originating node
Source of Information onNetwork Status
None Local Adjacent Nodes Nodes along route All nodes
Routing Strategy Fixed Flooding Random Adaptive
Adaptive Routing UpdateTime
Continuous Periodic Major load change Topology change
Packet Switched Packet Switched Network RoutingNetwork Routing
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 35
Data Switch Routing Data Switch Routing ExampleExample
Ethernet Switch Layer2 Operations Receives the Ethernet frame Looks up the 6-byte destination address in a forwarding table Sends the packet out only to the port associated with the
destination address
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 36
Ethernet SwitchEthernet Switch
10Base-T Switch
MAC #11 MAC #14MAC #13MAC #12
10Base-T Hub
MAC #21 MAC #24MAC #23MAC #22
Address Port UpdateTime
# 11 D 6:05.1441 PM # 12 C 6:04.1523 PM # 13 B 6:04.8722 PM # 14 A 6:05.1422 PM # 21 E 6:04.6623 PM # 22 E 6:04.2355 PM # 23 E 6:05.0233 PM # 24 E 6:04.9722 PM
FORWARDING TABLE
AE D C B
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 37
Data Network DevicesData Network Devices& the OSI Reference & the OSI Reference ModelModel
Gateways Routers Switches Hubs Bridges Repeaters
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 38
RepeaterRepeater
Layer 1 - Physical I physically repeat and regenerate bits for my own LAN
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 39
BridgeBridge
LAN 1 LAN 2
Layer 2 – Data Link Layer I link data frames by bridging between LANs
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 40
HubHub
USER
USER
USER
USER
Layer 2 – Data Link Layer I route packets between islands with common protocols
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 41
Data SwitchData SwitchUSER
USER
USER USER
Layer 2 – Data Link Layer I route packets between ports Packets are not sent to every port
(only to the destination port) Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 42
RouterRouter
Layer 3 – Network Layer I route packets between islands with common protocols
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 43
GatewayGateway
Layer 3+ I convert protocols between islands Synchronous to asynchronous
SYNC ASYNC
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 44
Data NetworkData NetworkDevices in DataDevices in Data
Network ApplicationsNetwork Applications
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 45
Router
Router
Router
Carrier Network
Router
ChicagoRouter
LAN Hub
Client
DetroitRouter
LAN Hub
Server
CustomerNetwork
CustomerNetwork
AccessLine
AccessLine
Typical Packet Data Typical Packet Data ServicesServices
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 46
Routers replace Layer 2 frame headers & trailers so packet can travel end-to-end over many links. They provide gateways into and out of the PSTN.
IP packets / TR frames
IP packets / PPP frames
Router or Gateway modifies frame
IP packets / TR frames
Router RouterCSU CSUC.O .
T1T1TokenRing
TokenRing
Packets, Routers, and Packets, Routers, and the PSTNthe PSTN
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 47
Combined NetworkCombined Network
CMTS
MSC TELCO
NIU NIU
HostDigital
Terminal
SS7 SS7
Internet
Intranet orPublic Data Network
Average ResidencePower ResidenceCorporate A Corporate B
Trunks toTelco
Switch
Gateway
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 48
IP Telephony Using a IP Telephony Using a Computer as the TerminalComputer as the Terminal
PSTN Internet
CODEC
Gateway
Router Cable Modem
Microphone
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 49
PSTN Internet
CODEC
Gateway
RouterCable Modem
TelephoneAdapter
IP Telephony Generates IP Telephony Generates Mobile-like TrafficMobile-like Traffic
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 50
Detecting and Fixing Detecting and Fixing ErrorsErrors
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 51
Detecting and Fixing Detecting and Fixing ErrorsErrors
Committed Information Rate (CIR) Data collisions Protocol analyzers
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 52
0 1 0 0 1 1 0 1 11 1 1 0 0 1 0 0 10 0 0 1 0 0 1 1 01 1 0 1 0 1 1 0 00 1 0 1 1 0 0 1 11 1 0 1 0 1 1 1 10 0 0 1 0 1 1 0 00 0 0 0 1 0 1 1 0
Block Parity Bits
BitPosition
1234567
CharacterParity
BlockParityCharacter
Block Parity CheckBlock Parity Check
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 53
New TermsNew Terms
Longitudinal Redundancy Check (LRC) Block Parity Check Checksum XMODEM checksum
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 54
Cyclic Redundancy Cyclic Redundancy Check (CRC)Check (CRC)
Data CRC Result
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 55
Automatic Repeat Automatic Repeat Request (ARQ)Request (ARQ)
Automatic Repeat Request (ARQ) Acceptance (ACK) Reject (NAK)
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 56
Forward Error CorrectionForward Error Correction
Mathematical creation of parity bits on the transmitting end and on the receiving end.
If the parity bits on each end match, there is no error. If the parity bits do not match, the error has been
detected. Forward Error Correction can correct errors, CRC
cannot.
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 57
Types of Digital Error Types of Digital Error MeasurementMeasurement
Bit Error Rate (BER)
Block Error Rate (BLER)
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 58
Digital Error Digital Error MeasurementMeasurement
Errored Seconds
Severely Errored Seconds
Source: KnowledgeLink,Inc
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 59
Shift Register
Clock
Interface Coder
Item under test
Interface Decoder
Error Counter
Shift Register
+
Illustration Courtesy of Hewlett Packard Source: Application Note 387
+
+ data
Error
Bit Error Rate TesterBit Error Rate Tester
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 60
Industry ContributorsIndustry Contributors
Lucent Technologies, Inc. (http://www.lucent.com) Telcordia Technologies, Inc (http://www.telcordia.com) KnowledgeLink, Inc (http://www.knowledgelinkinc.com)
The following companies provided materials and resource support for this module:
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 61
Individual ContributorsIndividual ContributorsThe following individuals and their industry or educational institutions provided materials, resources, and development input for this module: Dr. Bruce Black
Rose-Hulman Institute of Technology http://www.rose-hulman.edu/
Dr. Philip DiPiazza Florida Institute of Technology http://www.fit.edu/
Mr. Jay Junkus KnowledgeLink, Inc http://www.knowledgelinkinc.com
July 2001 Copyright 2001 Global Wireless Education Consortium S-BDN Switch - Basic Data Networks 62
Individual Contributors, Individual Contributors, cont.cont.
Mr. Ron Koziel KnowledgeLink, Inc http://www.knowledgelinkinc.com
Mr. Ken Robinson Ericsson http://www.ericsson.com
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