NetworksBasicsFinal.ppt
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Networking Basics
For : Level 1 – Networks and Computer Science DiplomaDeanship of Community Services and Continuous Education - Imam University
Based on : Cisco Networking Academy – Exploration 1
Instructor : Mahmoud Rabie
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Grading 15 for Attendance and Participation 35 for the Take-Home Open-Book Exam 50 for the Final Exam
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Topics Introduction to Networking Networking Fundamentals Networking Media Communicating over the Network Application Layer Functionality and
Protocols Ethernet and Link Layer
Addressing
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Introduction to Networking
Objectives
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Requirements for Internet Connection
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Network Interface Card (NIC)
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TCP/IP Description and Configuration
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Testing Connectivity with Ping
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Web Browser and Plug-Ins
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Troubleshooting Internet Connections
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Network Math ISA will be covered well, by Dr.
Baha
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IP Addresses and Network Masks
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Networking Fundamentals
Objectives
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Data Networks
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Networking Devices
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Network Topology
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Network Protocols
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Local-area Networks (LANs)
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Wide-area Networks (WANs)
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Storage-Area Networks (SANS)
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Virtual Private Networks (VPNs)
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Importance of Bandwidth
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Bandwidth Pipe Analogy
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Bandwidth Highway Analogy
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Bandwidth Measurements
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Bandwidth Limitations
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Using Layers to Analyze Problems
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Using Layers to Describe Data Communication
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OSI Model
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OSI Layers
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OSI Layers
•Provides connectivity and path selection between two host
•Provides Logical address
•No error correction, best effort delivery.
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OSI Layers
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OSI Layers
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OSI Layers
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OSI Layers
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OSI Layers
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Peer-to-Peer Communication
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TCP/IP Model
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Networking Media
Objectives
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Voltage
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Resistance and Impedance
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Current Flow
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Circuits
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Coaxial Cable
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Shielded Twisted-Pair Cable (STP)
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Unshielded Twisted Pair (UTP)
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Unshielded Twisted Pair (UTP)
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Unshielded Twisted Pair (UTP)
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Single Mode Fiber
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Multimode Fiber
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Optical Media
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Wireless LAN Standards
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Internal Wireless NIC
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Wireless USB Adapter
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Modulation
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Communicating over the Network
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Network Structure Define the elements of communication
3 common elements of communication message source the channel message destination
Define a network data or information networks capable of carrying many
different types of communications
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Network Structure Describe how messages are communicated
Data is sent across a network in small “chunks” called segments
Multiplexing
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Network Structure Define the components of a network
Network components hardware software
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Network Structure End Devices and their Role in the Network
End devices form interface with human network & communications network
Role of end devices: client server both client and server
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Network Structure Identify the role of an intermediary
device in a data network and be able to contrast that role with the role of an end device Role of an intermediary device
provides connectivity and ensures data flows across network
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Network Structure
Define network media and criteria for making a network media choice
Network media this is the channel over which a message travels
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Network Types
Define Local Area Networks (LANs) - A network serving a home, building or
campus is considered a Local Area Network (LAN)
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Network Types Define Wide Area Networks (WANs)
LANs separated by geographic distance are connected by a network known as a Wide Area Network (WAN)
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Network Types
Define the Internet The internet is defined as a global mesh of interconnected networks
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Network Types Describe network representation symbols
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Function of Protocol in Network Communication
The importance of protocols and how they are used to facilitate communication over data networks
A protocol is a set of predetermined or formal rules
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Function of Protocol in Network Communication
Explain network protocolsNetwork protocols are usedto allow devices to communicate successfully
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Function of Protocol in Network Communication
Define different protocols and how they interact
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Function of Protocol in Network Communication
Technology independent Protocols -Many diverse types of devices can communicate using the
same sets of protocols. This is because protocols specify network functionality, not the underlying technology to support this functionality.
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Layers with TCP/IP and OSI Model
Explain the benefits of using a layered model– Benefits include
• assists in protocol design• fosters competition• changes in one layer do not affect other layers• provides a common language
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Layers with TCP/IP and OSI Model
Describe TCP/IP Model
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Layers with TCP/IP and OSI Model
Describe the Communication Process
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Layers with TCP/IP and OSI Model
Explain protocol data units (PDU) and encapsulation
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Layers with TCP/IP and OSI Model
Describe the process of sending and receiving messages
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Layers with TCP/IP and OSI Model
Explain protocol and reference models
A protocol model provides a
model that closely matches the structure of a particular
protocol suite.
A reference model provides a
common reference for maintaining consistency within all types of network protocols and services.
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Layers with TCP/IP and OSI Model
Define OSI
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Layers with TCP/IP and OSI Model
Compare OSI and TCP/IP model
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Addressing and Naming Schemes
Explain how labels in encapsulation headers are used to manage communication in data networks
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Addressing and Naming Schemes
Describe examples of Ethernet MAC Addresses, IP Addresses, and TCP/UDP Port numbers
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Addressing and Naming Schemes
Explain how labels in encapsulation headers are used to manage communication in data networks
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Application Layer Functionality and Protocols
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Applications – The Interface Between Human and Data Networks
Explain the role of applications, services and protocols in converting communication to data that can be transferred across the data network
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Applications – The Interface Between Human and Data Networks
Define the separate roles applications, services and protocols play in transporting data through networks
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Describe the role protocols play in networking and be able to identify several message properties that can be defined by a protocol
Applications – The Interface Between Human and Data Networks
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The Role of Protocols in Supporting Communication
Describe the roles of client and server processes in data networks
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The Role of Protocols in Supporting Communication
List common Application Layers services and protocols
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The Role of Protocols in Supporting Communication
Compare and contrast client server networking with peer-to-peer networking and peer-to-peer applications
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Features, Operation, and Use of TCP/IP Application Layer Services
Describe the features of the DNS protocol and how this protocol supports DNS services
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Describe the features of the HTTP protocol and how this protocol supports the delivery of web pages to the client
Features, Operation, and Use of TCP/IP Application Layer Services
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Link Layer Addressing
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MAC Addresses and ARP 32-bit IP address:
network-layer address used to get datagram to destination IP
subnet
MAC (or LAN or physical or Ethernet) address: used to get datagram from one interface to
another physically-connected interface (same network)
48 bit MAC address (for most LANs) burned in the adapter
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LAN Addresses and ARPEach adapter on LAN has unique LAN address
Broadcast address= FF-FF-FF-FF-FF-FF
=adapter
1A-2F-BB-76-09-AD
58-23-D7-FA-20-B0
0C-C4-11-6F-E3-98
71-65-F7-2B-08-53
LAN(wired or
wireless)
•MAC address allocation administered by IEEE•Manufacturer buys portion of MAC address space (to assure uniqueness)
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ARP: Address Resolution Protocol
Each IP node (Host, Router) on LAN has ARP table
ARP Table: IP/MAC address mappings for some LAN nodes
< IP address; MAC address; TTL>
TTL (Time To Live): time after which address mapping will be forgotten (typically 20 min)
Question: how to determineMAC address of Bknowing B’s IP address?
1A-2F-BB-76-09-AD
58-23-D7-FA-20-B0
0C-C4-11-6F-E3-98
LAN
237.196.7.23
237.196.7.78
237.196.7.14
237.196.7.88
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ARP protocol: Same LAN A wants to send datagram to B, and B’s MAC address not in A’s ARP
table.
A broadcasts ARP query packet, containing B's IP address Dest. MAC address = FF-FF-FF-FF-FF-FF all machines on LAN receive ARP query
B receives ARP packet, replies to A with its (B's) MAC address frame sent to A’s MAC address (unicast)
A caches (saves) IP-to-MAC address pair in its ARP table until information becomes old (times out)
soft state: information that times out (goes away) unless refreshed
ARP is “plug-and-play”: nodes create their ARP tables without intervention from net administrator
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Star topology Nowadays, star topology prevails (يسود) Connection choices: hub or switch
hub orswitch
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Ethernet Frame Structure
Sending adapter encapsulates IP datagram (or other network layer protocol packet) in Ethernet frame
Preamble: 7 bytes with pattern 10101010 followed
by one byte with pattern 10101011 used to synchronize receiver, sender
clock rates
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Ethernet Frame Structure – Cont.
Addresses: 6 bytes If adapter receives frame with matching destination
address, or with broadcast address (eg ARP packet), it passes data in frame to net-layer protocol
Otherwise, adapter discards frame
Type: indicates the higher layer protocol (mostly IP)
CRC: checked at receiver, if error is detected, the frame is simply dropped
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Hubs
Hubs are essentially physical-layer repeaters: bits coming from one link go out all
other links at the same rate no frame buffering Adapters not Hub detect collisions
hub
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Interconnecting with hubs Backbone hub interconnects LAN segments Extends max distance between nodes But individual segment collision domains
become one large collision domain
hub
hubhub
Backbone hub
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Switch Link layer device
stores and forwards Ethernet frames examines frame header and selectively
forwards frame based on MAC destination address
when frame is to be forwarded on segment, uses CSMA/CD to access segment
Transparent hosts are unaware of presence of switches
Plug-and-play, self-learning switches do not need to be configured
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Forwarding
• How do determine onto which LAN segment to forward frame?• Looks like a routing problem...
hub
hubhub
switch1
2 3
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Self Learning
A switch has a switch table Entry in switch table:
(MAC Address, Interface, Time Stamp) stale entries in table dropped (TTL can be
60 min) Switch learns which hosts can be reached
through which interfaces when frame received, switch “learns”
location of sender: incoming LAN segment records sender/location pair in switch table
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Filtering/ForwardingWhen switch receives a frame:
index switch table using MAC dest addressif entry found for destination
then{ if dest on segment from which frame arrived
then drop the frame else forward the frame on interface
indicated } else flood
forward on all but the interface on which the frame arrived
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Switch ExampleSuppose C sends frame to D
• Switch receives frame from from C– notes in bridge table that C is on interface 1
– because D is not in table, switch forwards frame into interfaces 2 and 3
• Frame received by D
address interface
ABEGC
11231
hub
hub hub
switch
A
B CD
EF
G H
I
12 3
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Switch ExampleSuppose D replies back with frame to C.
• Switch receives frame from from D– notes in bridge table that D is on interface 2
– because C is in table, switch forwards frame only to interface 1
• Frame received by C
hub
hub hub
switch
A
B CD
EF
G H
I
address interface
ABEGCD
112312
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Switch: Traffic Isolation Switch installation breaks subnet into LAN
segments Switch filters packets:
same-LAN-segment frames not usually forwarded onto other LAN segments
segments become separate collision domains
hub hub hub
switch
collision domain collision domain
collision domain
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Switches: Dedicated Access Switch with many
interfaces Hosts have direct
connection to switch No collisions; full
duplex
Switching: A-to-A’ and B-to-B’ simultaneously, no collisions
switch
A
A’
B
B’
C
C’
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Switches vs. Routers Both store-and-forward devices
routers: network layer devices (examine network layer headers)
switches are link layer devices Routers maintain routing tables, implement routing algorithms Switches maintain switch tables, implement filtering, learning
algorithms
Switch
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Summary Comparison
hubs routers switches
traffi c isolation
no yes yes
plug & play
yes
no
yes
optimal routing
no
yes
no