Cloud and Network Technology Notes

The Mainframe Era (1960s - 1980s)

  • Characterized by thin client architecture.
  • All applications, data storage, and processing occur on the mainframe.

The Client-Server Era (1990s - 2000s)

  • Shift towards stand-alone clients and servers.
  • Applications, data storage, and processing are distributed between the client and server.
  • Introduction of the Internet.

The Cloud Computing Era (2008-Present)

  • Cloud service providers manage applications, data storage, and processing.
  • Various client types: IoT devices, mobile, thin, and stand-alone clients.

Why Cloud Computing?

  • Elasticity: Resources can be quickly scaled up or down based on demand.
  • Organizations pay only for the resources they use.
  • Flexibility to handle unpredictable demand with limited financial risk.
  • Pooled Resources: Multiple organizations share the same physical hardware through virtualization.
  • Eliminates the need for building infrastructure to support maximum demand.
  • Economies of Scale: Cloud vendors achieve lower average production costs due to their large-scale operations.

Cloud vs. In-House

  • Cloud (Pros):
    • Small capital requirements, rapid development.
    • Superior scalability for fluctuating demand.
    • Known cost structure.
    • Potential for best-of-breed security and disaster preparedness.
    • Elimination of obsolescence.
    • Industry-wide economies of scale, thus cheaper.
    • Focus on core business, not infrastructure.
  • Cloud (Cons):
    • Dependency on vendor.
    • Loss of control over data location.
    • Limited visibility into true security and disaster preparedness capabilities.
  • In-House (Pros):
    • Control of data location.
    • In-depth visibility of security and disaster preparedness.
  • In-House (Cons):
    • Significant capital and development effort required.
    • Difficult to accommodate fluctuating demand.
    • Ongoing support costs and personnel training.
    • Increased management requirements and annual maintenance costs.
    • Cost uncertainties and obsolescence.

When Cloud Doesn't Make Sense

  • When laws or industry standards require physical control or possession of data.
  • Example: Financial institutions might be legally required to maintain physical control over their data.

Three Fundamental Cloud Types

  • SaaS (Software as a Service):
    • Users: Employees, customers.
    • Examples: Salesforce.com, iCloud, Office 365.
  • PaaS (Platform as a Service):
    • Users: Application developers, application testers.
    • Examples: Google App Engine, Microsoft Azure, AWS Elastic Beanstalk.
  • IaaS (Infrastructure as a Service):
    • Users: Network architects, systems administrators.
    • Examples: Amazon EC2 (Elastic Compute Cloud), Amazon S3 (Simple Storage Service).

Cloud Services as Transportation

  • Traditional (On-Premises): Build a car (manage everything: gas, driving, insurance, cleaning, repairs, registration, testing, assembly, auto parts).
  • IaaS: Buy a car (vendor manages repairs, registration, testing, assembly, auto parts; you manage gas, driving, insurance, cleaning).
  • PaaS: Rent a car (vendor manages driving, insurance, cleaning, repairs, registration, testing, assembly, auto parts; you manage gas).
  • SaaS: Take a taxi (vendor manages gas, driving, insurance, cleaning, repairs, registration, testing, assembly, auto parts).

Secure Cloud Usage

  • Encryption
  • Firewall
  • VPN (Virtual Private Network)

Encryption

  • Process of transforming clear text into coded text.
  • Used for secure storage or communication.
  • Employs algorithms and keys.
  • Algorithm applies a key to produce a coded message.

Public Key/Private Key Encryption

  • Public key encrypts messages.
  • Public key is sent to the other party to encode messages for secure return.
  • Private key decodes messages.
  • HTTPS: Secure communication over the Internet using SSL/TLS protocol.
  • Messages are encoded using a website's public key and decoded with a private key.

Firewalls

  • A computer device that prevents unauthorized network access.
  • Can be special-purpose hardware or software.
  • Organizations may have multiple firewalls.
    • Perimeter firewalls sit outside the organizational network.
    • Internal firewalls are inside the network.
  • Packet-filtering firewalls examine source and destination addresses before allowing messages to pass.
  • Filtering occurs for both incoming and outgoing messages.

VPNs (Virtual Private Networks)

  • Use the Internet or private network to create the appearance of point-to-point connections.
  • Uses the public Internet to create a private network appearance.
  • Client and server have a point-to-point connection called a tunnel.
  • Provides a private pathway over a shared network (secure, encrypted communications).

Networks and Communication

  • Rapid communication is essential for customers, suppliers, and employees.
  • Pre-1990s communication: postal system, telephone (voice and fax).
  • Modern communication: E-mail, instant messages, Internet, cell phones, mobile computers connected to wireless networks.

Computer Networks

  • Network: Collection of computers that communicate with one another over transmission lines.
  • Three basic types:
    • Local Area Network (LAN)
    • Wide Area Network (WAN)
    • Internet
  • A fourth type:
    • Personal Area Network (PAN) – connects devices around a single person.

Basic Network Types

  • PAN (Personal Area Network): Devices connected around a single person.
  • LAN (Local Area Network): Computers connected at a single physical site.
  • WAN (Wide Area Network): Computers connected between two or more separated sites.
  • Internet: Network of networks.

LAN Components

  • Connects computers in a single location.
  • 2 to several hundred computers.
  • One geographic area.
  • Communication lines can be placed where the organization wants.

WAN Components

  • Connects computers in different geographical areas.
  • Two or more cities.
  • Uses communication networks from vendors.
  • Licensed by the government.

Internet

  • Network of networks.
  • Connects LANs, WANs, and other internets.
  • Uses a variety of communication methods and conventions.
  • Seamless data flow via layered protocol.
  • Protocol: Set of rules that communicating devices follow.

How the Internet Works

  • Internet Service Provider (ISP) connects your LAN to the Internet.

LAN Components

  • Computers connected on a single company site.
  • Located within a half-mile area.
  • Property controlled by company operating network.
  • Components:
    • Switch: Special purpose computer that receives and transmits messages.
    • Network Interface Card (NIC): Hardware that connects each device’s circuitry to the cable (onboard or expansion slot).
    • MAC Address (Media Access Control): Unique identifier (e.g., 00-0C-F1-56-98-AD).

SOHO (Small Office/Home Office) Network

  • LAN devices act as a router, switch, and wireless access point (AP).
  • Wired connections use IEEE 802.3.
  • Wireless connections use IEEE 802.11.

SOHO LAN Topology

  • Transmission Line Type:
    • UTP or optical fiber.
  • Transmission Speed:
    • Common: 10/100/1000 Mbps.
    • Possible: 1 Gbps.
  • Equipment Used:
    • Switch, NIC
  • LAN with wireless:

Connecting LAN to the Internet

  • WAN Wireless Connection
  • Cable Line – uses cable television lines
  • DSL – Digital Subscriber Line
    • Operates on the same lines as voice telephones.
    • Does not interfere with voice telephone signals/service.
  • THREE types of WAN connections
  • ISP – Internet Service Provider
    • Provides you with a legitimate Internet address
    • Serves as your gateway to the Internet
    • ISPs pay for the Internet

Connecting to an ISP

  • When you connect to the Internet, you connect to an Internet Service Provider (ISP).
  • An ISP has 3 functions:
    • Provides you with a legitimate Internet address
    • Serves as your gateway to the Internet
    • Pays for the Internet

How to Connect to an ISP

  • Three types of WAN connection:
    • Digital Subscriber Line (DSL):
      • Operates on the same lines as voice telephones.
      • Does not interfere with telephone signals.
      • Data transmission and telephone conversations can occur simultaneously.
      • Phone company separates and sends data to ISP.
    • Cable Line:
      • High-speed using cable television lines.
    • WAN Wireless Connection:
      • Example: iPhone uses a LAN-based wireless network if available and WAN if not.

How the Internet Works

  • Simplified example:
    • Postal System: Package, person's name, mailing address.
    • Internet: Packet, domain name, IP address.

Communications Protocol

  • Standardized means for coordinating activities.
  • Sequence of ordered steps.
  • Means for coordinating activities between communicating computers.
  • Computers agree on protocol to use.
  • Broken down into layers.

TCP/IP

  • Transmission Control Protocol / Internet Protocol.
  • Allows diverse hardware and software components to communicate.
  • Developed in the early 1970s for DARPA.
  • TCP:
    • Data between computers.
    • Establishes connection.
    • Sequences the transfer of packets.
    • Acknowledges packets sent.
  • IP:
    • Delivery of packets.
    • Disassembling and reassembling packets.

TCP/IP-OSI Architecture

  • Layer 5: Application (Interoperability of application)
  • Layer 4: Transport (Transmission across an internet)
  • Layer 3: Internet (Transmission across an internet)
  • Layer 2: Data Link (Transmission across a single network)
  • Layer 1: Physical (Transmission across a single network)

Network Addresses: MAC and IP

  • MAC (Media Access Control) addresses:
    • Used WITHIN the network.
    • Physical addresses.
    • Implemented by programs using Layer 2 protocols.
    • Each NIC card is given an address by the manufacturer.
    • Address only shared within network or segment.
  • IP Addresses:
    • Logical addresses.
    • Written as a series of dotted decimals (e.g., 192.68.2.28).
    • Not permanently associated with hardware device.
    • Can be reassigned as necessary.

Domain Name System (DNS)

  • Converts user-friendly names into public IP addresses.
  • Resolves domain names.
  • ICANN manages resolution system.
  • Domain name: Registered name (cybersquatting?).
  • Uniform Resource Locator (URL): Document’s Web address.

Domain Name Resolution

  • ICANN (Internet Corporation for Assigned Names and Numbers) manages root servers.
  • 13 computers across the world.
  • Maintain lists of IP addresses of servers.
  • Domain name resolvers
    • Cache name and IP address on local file.
    • Used instead of going through the entire resolution process.

Network Topologies

  • How the network components are connected.
  • Star Network: All network components connect to a single hub.
    • Extended star: Multiple switches connected in a hierarchy.
    • Now most common topology.
  • Bus Network: Signals are broadcast to entire network – software ‘listens’ for messages addressed specifically to it.
    • Previously most common for small, wired networks.
  • Ring Network: Components are connected in a closed loop.
    • Messages pass from one computer to the next, one at a time.
    • Older LANs using Token Ring networking software.

Remote Access Systems

  • Reduces the value of local mediocrity.
  • Telediagnosis: Healthcare
  • Telesurgery: Robotics
  • Telelaw: Issue tickets
  • Sporting Events
  • Metropolitan Opera performances with Met Live broadcasts

Future Cloud Services

  • In addition to IaaS, PaaS, and SaaS, Cloud service providers may provide:
    • AaaS: Analytics as a Service - analyze big data they’re collecting
    • PBaaS: Business Process as a Service - outsource common business processes like shipping and procurement
    • EaaS: Everything as a Service - outsource all aspects of your business EXCEPT where you add value