Transcript Chapter 5

Chapter 5
Data Communication
And
Internet Technology
Purpose
• Understand the fundamental networking
concepts
Agenda
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Network Concepts
Communication Protocol
TCP/IP-OSI Architecture
Network Types
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LAN
WAN
Public Switched Data Network
Virtual Private Network
Network Comparison
Internet
Domain Name System
IP Addressing Schemes
Security
Discussion and Case Study
Network Concepts
• A collection of computers that
communicate with one another over
transmission lines
• Types
– Local area networks (LANs): connects
computers in a single geographic location
– Wide area networks (WANs): connects
computers at different geographic sites
– Internet: a network of networks
Communication Protocol
• Protocol: a standard means for
coordinating an activity between two or
more entities
• Communications protocol: a means for
coordinating activity between two or more
communicating computers
– The communication protocol is broken into
levels of layers
– Two machines must agree upon and follow
the protocol for exchanging the message
TCP/IP-ISO Architecture - I
• International Organization for
Standardization (ISO): Reference Model
for Open Systems Interconnection (OSI)
• Internet Engineering Task Force (IETF):
Transmission Control Program/Internet
Protocol (TCP/IP)
• TCP/IP-ISO architecture: five layers
TCP/IP-ISO Architecture - II
• Layer 5 (Application): communication rules
between two applications
– Simple Mail Transfer Protocol (SMTP) for
email
– Hypertext Transfer Protocol (HTTP) for
processing Web page (sites and users)
– File Transfer Protocol (FTP) for copying file
between computers
TCP/IP-ISO Architecture - III
• Layer 4 (Transport): communication rules
between two host computers
– Transmission Control Program (TCP)
– Sending functions: break data into segments,
add To and From address, and
– Receiving functions: provide reliability by
sending acknowledgement, and translate the
format, assemble segments into data
TCP/IP-ISO Architecture - IV
• Layer 3 (Internet): communication rules of
routing packets across the Internet
– Internet Protocol (IP)
– Functions: package each segment into a
packet, place IP data in in the packet, add
To/From data
TCP/IP-ISO Architecture - V
• Layer 2 (Data Link): communication rule
for transmitting data within a single
network
– Functions: package packets into frames
• Layer 1 (Physical): communication rule
between adjacent device connected by a
transmission medium
Terminology
• Architecture: an arrangement of protocol layers
with their associated tasks
• Protocol: set of rule to accomplish the tasks
• Program: software implementing the protocol
• Web: sub set of Internet with users and sites to
process protocol
• Internet: communication structure
• Browser: a program implementing the HTTP of
the TCP/IP-OSI architecture (Netscape and
Microsoft Internet Explorer)
TCP/IP-OSI Application Example
Network Types
• LAN: local area network
• WAN: wide area network
LAN - I
• A group of computers connected together
on a single company site and operated by
the company
• Equipments
– Network interface card (NIC) or onboard NIC:
an unique identifier named MAC (media
access control) address
– Unshielded twisted pair (UTP) cable with RJ45 connecter
– Optical fiber cable with ST and SC connectors
LAN - II
• IEEE (Institute for Electrical and Electronics
Engineers)
• Protocol: IEEE 802.3 or Ethernet
– Hardware characteristics (which wire carries which
signals)
– Package and process message over LAN
– Operate on Layer 1 and 2
• 10/100/1000 Ethernet (Mbps)
• Bits for communications speeds and bytes for
memory sizes
Local Area Network
NIC Interface Card
Unshielded Twisted Pair (UTP) Cable
Optical Fiber Cable
LAN - III
• Wireless LAN
– Wireless NIC (WNIC)
– IEEE 802.11g protocol to connect to an
access point (AP) and IEEE 802.3
Wireless Access Standards
Wireless LAN
WAN
• Connects computers located at physically
separated sites
• Internet service provider (ISP)
– Provide customer a legitimate Internet address.
– Serve as the gateway to the Internet
– Communicate between sending computer and
Internet
• Connecting computer and ISP
– Telephone line
– DSL (digital subscriber line)
– Cable TV line
WAN - Equipment
• Modem
– Convert data between digital and analog
– Narrowband with speed less than 56 kbps and Broadband with speed
over 256 kbps
• Modem types
– Dial-Up modem
• Narrowband
• Point-to-Point Protocol (PPP)
– DSL modem
• Permanent connection and one more line for telephone conversation
• Asymmetric digital subscriber line (ADSL) for home and small business with
slow upload speed with 256 kbps and faster download speed ranging from
256 to 768 kbps
• Symmetric digital subscriber line (SDSL) for advanced users and larger
business with 1.544 Mbps performance level guarantees
– Cable modem
• Permanent connection and one more line for TV
• 10 Mbps download speed and 256 kbps upload speed
Analog vs. Digital Signals
Personal Computer (PC) Internet Access
WAN - Equipment
• Access devices
– Switch (Layer 2)
– Router (Layer 3)
• Lease lines from telecommunication
company
– T1 line with 1.544 Mbps speed
– T3 line with 44.763 Mbps speed
– Optical fiber cable-768 with 40 Gbps
– Point-to-Point Protocol (PPP)
Transmission Line Types, Uses, and Speeds
WAN – Public Switched Data Network
• Public switched data network (PSDN)
• Developed and maintained by a vendor for selling time to
other company
• Shown as a cloud in the map or diagram
• User must have a leased line connecting to PSDN as
point of presence (POP)
• PSDN types
– Frame Relay with 56 kbps to 40 Mbps: slower and cost less but
simple and easy to support
– Asynchronous transfer mode (ATM) with 1 to 156 Mbps: faster
and cost more but transmitting data and voice
– Ethernet with 10 to 40 Gpbs
Wide Area Network Using PSDN
WAN – Virtual Private Network
• Virtual private network (VPN): a private
internet as a private point-to-point
connection
• Tunnel: a virtual, private pathway over a
public or shared network from the VPN
client to the VPN server
• Encrypted message
• Remote access
Remote Access Using VPN
Wide Area Network Using VPN
Network Comparison
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Setup costs
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Operational costs
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Lease fees for line and equipment
ISP charges
Training
Maintenance: problem diagnosis, repair, and updating
Performance
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Equipment: lines, switches, routers, and access devices
Labor
Speed: line and equipment
Latency: transmission delay due to congestion
Availability: service outages
Loss rate: transmission problem
Transparency
Performance guarantee: availability, error rate, speed, etc.
Growth potential
Contract commitment period
Management time
Financial risk
Technical risk
Summary of LAN and WAN Networks
Internet
• Network address
– Physical or MAC address in Layer 2 program: permanent and
unique
– Logical or IP address in Layers 3, 4, and 5: not permanent, such
as 192.168.2.28
– Public IP address used on the Internet to major institutions in
blocks assigned by Internet Corporation for Assigned Names
and Numbers (ICANN)
– Private IP address used within private networks and internets
• DHCP server has Dynamic Host Configuration Protocol
(DHCP) to assign a temporary IP address for accessing
the Internet
• Network Address Translation (NAT): The process of
changing public IP addresses into private IP addresses,
and the reverse
Domain Name System
• Convert user-friendly name into their IP address
• domain name: any registered, valid name with ICANN
• resolving the domain name: the process of changing a
name into its IP address
– ICANN has 13 computer as root servers for maintaining a list of
IP addresses of servers to resolve each type of TLD in the world
• Top-level domain (TLD)
– Non-U.S. is the two letter abbreviation for the country
– U.S. is the type of organization
• Uniform resource locator (URL): document’s address on
the Web
• Domain name resolvers store the correspondence of
domain names and IP address
IP Addressing Schemes
• IPv4 and
• IPv4
– 32 bits divided into four groups of 8 bits, and a
decimal number represents each group
– 63.224.57.59
– The largest decimal number between the period is
255 (0 – 255)
• IPv6
– 128 bits due to the growth of the Internet
– Currently both IPv4 and IPv6 are used on the Internet
Security
• Encryption algorithms: DES, 3DES, AES
• Key
– Symmetric encryption
– Asymmetric encryption: public key and private key
• HTTPS
– Secure Socket Layer (SSL) and Transport Layer
Security (TLS)
– Public key, private key and symmetric encryption
Summary
• TCP/IP-OSI five layers
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Application layer
Transport layer
Internet layer
Data link layer
Physical layer
• Public switched data network (PSDN)
• Dynamic Host Configuration Protocol (DHCP) to
assign a temporary IP address for accessing the
Internet
• Domain name
Discussion
• Problem solving (121a-b)
– What are the new opportunities for the business generated by the Internet?
– What are the new threats for the business generated by the Internet?
• Opposing forces (129a-b)
– State your opinions related to the negative impact on the society when
everyone is connect through the Internet.
• Security (133a-b)
– State the impacts on the society and business from the government
having an decryption method to decode everything over the Internet.
• Ethics (141a-b)
– State the impacts from the employee’s private usage of company’s
computer facility.
• Reflections (143a-b)
– How should you react properly from not getting lost from this Internet age?
Case Study
• Case 5-1 (148-149) Network Services:
questions 1, 3, 4, 5, 6, 9, and 10
Points to Remember
•
•
•
•
Network Concepts
Communication Protocol
TCP/IP-OSI Architecture
Network Types
–
–
–
–
•
•
•
•
•
•
LAN
WAN
Public Switched Data Network
Virtual Private Network
Network Comparison
Internet
Domain Name System
IP Addressing Schemes
Security
Discussion and Case Study