Chapter 5

Data Communication

And

Internet Technology

Purpose

• Understand the fundamental networking concepts

Agenda• 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

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 RJ-45 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• Setup costs

– Equipment: lines, switches, routers, and access devices– Labor

• Operational costs– Lease fees for line and equipment– ISP charges– Training– Maintenance: problem diagnosis, repair, and updating

• Performance– 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– 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