Standardization Organizations

• Standards are documented agreements containing technical specifications or precise criteria for product/service design and performance.

Common Standardization Organizations

• Institute of Electrical and Electronics Engineers (IEEE) promotes development/education in electrical engineering and computer science.
• IEEE's Project 802 standardized LAN technologies like Ethernet (802.3), token-ring (802.5), and Wireless LAN (802.11).
• American National Standards Institute (ANSI) has over one thousand industry and government representatives determining standards for various fields.
• ANSI publishes standards, such as American Standard for Code Information Interchange (ASCII) and Small Computer System Interface (SCSI).
• Electronic Industries Alliance (EIA) is a trade organization of electronics manufacturers writing ANSI standards and legislation.
• Telecommunications Industry Association (TIA) focuses on standards for information technology, wireless, satellite, fiber optics, and telephone equipment.
• TIA/EIA 568 – B Series" are the alliance's guidelines for network cable installation in commercial buildings.
• Internet Engineering Task Force (IETF) develops the Internet and internetworking technologies and sets standards for communication.
  • The Internet Society (ISOC) oversees overall Internet development.
  • The Internet Engineering Steering Group (IESG) manages IETF activities and the process for introducing/updating Internet standards.
  • The Internet Architecture Board (IAB) is the technology advisory group to the Internet Society, responsible for protocol and architecture development.
  • The Internet Assigned Numbers Authority (IANA) oversees Internet naming/addressing and manages "unique parameters," including IP addresses.
• The International Organization for Standardization (ISO) develops a wide range of standards relevant to networking.

Application Layer Protocols

• The application layer provides interfaces for application software to use network services and designates transport layer protocols and ports.
• Simple Mail Transfer Protocol (SMTP) is a TCP/IP protocol for reliable and efficient electronic mail transfer.
• Post Office Protocol, version 3 (POP3) retrieves mail for a workstation from a server using TCP/IP.
• Trivial File Transfer Protocol (TFTP) uses UDP to transfer files and serves as a small alternative to FTP.
• File Transfer Protocol (FTP) uses TCP/IP to share computer programs/data between hosts, creating virtual connections for control/data transfer.
• Network File System (NFS) allows computers to mount drives on remote hosts and operate them as local drives using TCP/IP.
• Domain Name System (DNS) translates domain names and their network nodes into IP addresses using TCP/IP.
• Simple Network Management Protocol (SNMP) manages network information exchange, and enables administrators to manage configurations, performance and security, with three components:
  • Managed devices collect/store management information for NMSs using SNMP.
  • An agent translates management information into a format compatible with SNMP.
  • NMS executes applications to monitor/control managed devices and provides processing / memory resources.
• Terminal Emulation Protocol Network (Telnet) utilizes TCP to facilitate connection between a server and client.
  • Telnet employs a daemon which is a remote host, and establishes a Virtual Terminal (VTY) session

Remote Login and Transfer Protocols

• Remote login application (rlogin): Allows authorized UNIX users to log into other UNIX machines (hosts) on a network.
• Hypertext Transfer Protocol (HTTP): Supports information exchange on the World Wide Web and internal networks.
• HTTPS (Hypertext Transfer Protocol over Secure Socket Layer): A secure communications protocol used with HTTP.
• Secure Sockets Layer (SSL): Exists between the TCP layer and the application layer to encrypt/decode and authenticate data.

TCP and UDP Connections

• Computers on the Internet use Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) to communicate.
• Transport Control Protocol (TCP) is a connection-oriented TCP/IP protocol:
  • TCP provides reliable data delivery, data suppression, congestion control, and flow control.
  • Transport protocols deliver information from one port to another facilitating communication between applications.
  • TCP ensures reliability through error detection and error correction.
• User Datagram Protocol (UDP) is a connectionless TCP/IP protocol that provides best-effort service.
  • UDP sends independent packets called datagrams without guaranteed arrival.
  • Sending datagrams is like sending letters; order isn't important/guaranteed and each message is independent.

Ports

• Data transmitted includes addressing information for the computer and port.
• The computer is identified by its 32-bit IP address.
• Ports use a 16-bit number to deliver data to the identified application using TCP and UDP.
• Port numbers range from 0 to 65,535.
• Ports 0-1023 are restricted and reserved for well-known services such as HTTP and FTP.

TCP and UDP Formats

• TCP Header Fields:
• Source Port: identifies the sending application (16 bits).
• Destination Port: identifies the receiving application (16 bits).
• Sequence Number: refers to every byte of data sent over a TCP connection (32 bits).
• Acknowledgment Number: sequence number of next byte receiver expects (32 bits).
• Header Length: length of TCP header in 32-bit units (4 bytes).
• Reserved: always set to 0 (6 bits).
• Control Bits: include FIN, ACK, SYN flags.
• Window: for TCP flow control and indicates maximum bytes allowed by receiver.
• Checksum: a mandatory field which is calculated/stored by the sender and verified by the receiver.
• UDP Header Fields:
• Source Port: identifies the sending application (16 bits).
• Destination Port: identifies the receiving application (16 bits).
• Length: total length of UDP header plus data; minimum length is 8 bytes.
• Checksum: refers to the checksum of the UDP header and UDP data.

Handshake

• SYN-ACK Handshake:
• Three-way handshake: sender and receiver inform operating systems of an impending connection
  • SYN (Synchronize)
  • ACK (Acknowledge)
  • FIN (Finish)
• The Sequence Number and Acknowledgment Number fields facilitate reliable and ordered data transmission.
• Window Sliding Mechanism requires the sender to receive acknowledgement after transmitting data.
• TCP Shutdown (Four-Way Handshake): Disconnects TCP connection and releases system resources when data transmission completes.

IP Addressing and Subnetting

• The Internet Protocol (IP) has two versions: IP version 4 (IPv4) and IP version 6 (IPv6).

• MAC (Media Access Control) address: A unique physical address of a computer, assigned by the manufacturer.
  • Organizational Unique Identifier (OUI): The first 24 bits of MAC indicate the vendor.
  • Vendor-Assigned: Remaining 24 bits incrementally assigned denoting the serial number of the device.

IP Addresses

• An IP address is assigned to uniquely identify a device on an IP network.
  • Public IP Address: used to find/exchange information assigned by the ISP.
    • Static Public IP Address: fixed IP primarily for hosting web pages or services.
    • Dynamic Public IP Address: Chosen from a pool, changing each connection.
  • Private IP Address: Used by computers on a network to communicate with the router and can change with each new session. Parts of an IP Address
  • network ID: identifies the host on the same physical network.
  • host ID: identifies the workstation, server, and router within a network.

IPv4 Classes

• Class A: Uses only the first octet (8 bits) for network address, using all other octets for host addresses.
  • 1.0.0.0 to 127.0.0.0
  • Network.Host.Host.Host
  • Number of Bits used in Network / Host – 24
  • Maximum Host of Network – 16,777,214
• Class B: Uses two octets (16 bits) for the network address.
  • 128.0.0.0 to 191.255.255.255
  • Network.Network.Host.Host
  • Number of Bits used in Network / Host – 16
  • Maximum Host of Network – 65,534
• Class C: Uses three octets (24 bits) to identify the network portion.
  • 192.0.0.0 to 233.255.255.255
  • Network.Network.Network.Host
  • Number of Bits used in Network / Host – 8
  • Maximum Host of Network – 254
• Class D: Used to enable multicasting by using an IP address.
  • 224.0.0.0 to 239.255.255.255
  • Host.Host.Host.Host
  • This requires its first four bits be "1110". Its first octect range is 224-239
• Class E: Reserved by the IETF for research.
• 240.0.0.0 to 255.255.255.255 (First four bits are set to "1111")

IANA IPv4 Special-Purpose Addresses

• Diagnostic (Loopback/Localhost Address): Used for debugging programs and hardware.
  • 127.0.0.0 – 127.255.255.255 (SYN-ACK)
• Default Network: Used for routing internet datagram (TCP).
  • 0.0.0.0
• Network Broadcast: Used to broadcast to an entire network.
  • 255.255.255.255
• Private-use of Internet Space: Preconfigured for network devices extending IPv4 spaces.
  • 10.0.0.0 – 10.254.254.254
  • 172.16.0.0 – 172.16.254.254
  • 192.168.0.0 – 192.168.254.254
• Link-Local Addresses: Selected/configured if DHCP isn't there.
  • 169.254.0.0 – 169.254.254.254
• Subnet Mask (Default Mask): Designates which portion of an IP is host and which is network.

Binary to Dotted Decimal Conversion

• Binary value conversion can be done for each octet, and then concatenated for a full IP address in dotted decimal form.
• Subnet Masking:
• "ANDing" the default mask in binary with the IP address determines the network and host sections.

Subnetting

• It refers to the process of borrowing bits from the host ID field to form a new subnet ID field.
• Default masks are used in this process.
• A custom subnet mask is determined by masking, supporting different sizes of networks.

IPV6

• The Internet was rapidly expanding, which was unforeseen before, so IETF technologies like NAT and CIDR were used.
• IANA announced full IPv4 allocation on February 3, 2011 to several Regional Internet Registries (RIRs). IPv4 officially used up November 25, 2019.
• December 1998 IPv6 became the standard.
• Internet Protocol version 6 (IPv6) is a set of specifications designed by the IETF, which is an upgraded version of IPv4. Also known as IP Next Generation (IPng).
  • It is 128 bits.
  • It Uses Colons.
• IPV6 Abbreviation Specifications:
• The leading 0s in each 16-bit segment can be omitted.
• One 0 must be present in a segment, if all bits are 0s
• Double colons represent consecutive 0s, but are only used once in address.
• IPv6 Address Classification
• Unicast
• Multicast
• Anycast

Sample Space, Relationships Among Events, and Rules of Probability

• Probability relates to likelihood of an event, not providing guarantees.
• Probabilities fall into 2 branches: -- Subjective is theoretical and based on past experience and can have bias from person to person --Objective is empirical and examines data using logical equations

Probability Formula

• P(E) means the probability that an "Experiment" has chance of having "Event" happen
• E means the number of possible outcomes are in a single "Event"
• S means all possible "Event/Experiment" sets

Properties

1. Between 0% and 100%
2. Probability cannot be less than 0 (0%)
3. Probability cannot be more than 1 (100%)

• There are two "probability of occurence" rules "OR" and "AND": --Rule "OR" has 2 sub-branches
• 1. Mutually exclusive: probability of separate events which when summed, equal total probability of each event.
• 2. Not mutually exclusive: opposite of above.
• The other rule "AND" involves multiplication of events.

Multiplication Rule

• Events that are independent occur when probability doesn't affect the "Event" that unfolds.
• Dependent events, do affect their specific happenings.

Counting Principles

• Multiplication Principle* When there is an event with two possible ways, you simply multiply their possible outcomes with each other.
• Permutations* Is a technique that refers to the arrangement or ordering of a set of objects.
• The Formula for this is !P = ! / (! r ) (! = factorial)
• You can also re-apply permutations but some "events" are similar where this is a formula for that too.
• !P= ! / (! x ! ...... !)*
• Combination*: Objects are chosen at random.
  • The formula for it is: C ( ,) = ! /( ! (!))