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Chapter 3 Network Protocols and Communications (3.The Benefits of Using a…

- - - - Prior to communicating, they must agree on how to communicate:
        • If the communication is using voice, they must first agree on the language.
        •Next, when they have a message to share, they must be able to format that message in a way that is understandable.
        For example, if someone uses the English language, but poor sentence structure, the message can easily be misunderstood.
- - - - After formatting (encoding) a message, the message must be placed inside another message (encapsulation).
        Just as a letter is encapsulated in an envelope for delivery: 📃⮕ ✉
        
        Data encapsulation
        
        Each computer message is encapsulated in a specific format, called a frame, before it is sent over the network. A frame acts like an envelope
        
        The frame has a source and destination in both the frame addressing portion and in the encapsulated message.
        
        physical / hardware addres: 🏠
        recipient/sender: 🚶
        
        Message size
        
        When people communicate with each other, the messages that they send are usually broken into smaller parts or sentences. ✉ ✉ ✉
        
        The size restrictions of frames require the source host to break a long message into individual pieces that meet both the minimum and maximum size requirements
        
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        Message Timing
        
        🔊 Access Method: Determines when someone is able to send a message. Hosts on a network need an access method to know when to begin sending messages and how to respond when collisions occur.
        
        ✉ ✉ ✉Flow control: source and destination hosts negotiate how much information can be sent and the speed that it can be delivered.
        
        ⏱ Response Timeout: Hosts on the network have rules that specify how long to wait for responses and what action to take if a response timeout occurs
        
        Message Delivery Options
        
        Unicast: A one-to-one delivery (💻⮕ 💻)💻💻
        
        Multicasting is the delivery of the same message to a group of host destinations, one-to-many: (💻⮕ 💻💻) 💻
        
        Broadcasting represents a one-to-all message delivery option (💻⮕ 💻💻💻)
        
        Segmentation: breaking communication into pieces
        
        Segmentation can increase the efficiency of network communications. If part of the message fails to make it to the destination, due to failure in the network or network congestion, only the missing parts need to be retransmitted.
        
        Multiplexing: Sending small individual pieces from many different senders by interleaving the segments
        
        The form that a piece of data takes at any layer is called a protocol data unit (PDU)
- - - - A ways to visualize how the protocols within a suite interact is to view the interaction as a stack. The protocols are viewed in terms of layers
- - - - The 4-layer TCP/IP model is a protocol model because it describes the functions that occur at each layer of protocols within the TCP/IP suite.
    - - A reference model is not intended to be an implementation specification or to provide a sufficient level of detail to define precisely the services of the network architecture.
- - - - Standards organizations are important in maintaining an open Internet with freely accessible specifications and protocols that can be implemented by any vendor: IEEE, IETF, IANA, ICANN, ITU, TIA
        
        Internet Society (ISOC) – Responsible for promoting the open development and evolution of Internet use throughout the world.
        
        Internet Architecture Board (IAB) - Responsible for the overall management and development of Internet standards.
        
        Internet Engineering Task Force (IETF) - Develops, updates, and maintains Internet and TCP/IP technologies. This includes the process and documents for developing new protocols and updating existing protocols know as Request for Comments (RFC) documents.
        
        Internet Research Task Force (IRTF) - Focused on long-term research related to Internet and TCP/IP protocols such as Anti-Spam Research Group (ASRG), Crypto Forum Research Group (CFRG), and Peer-to-Peer Research Group (P2PRG).
        
        Internet Corporation for Assigned Names and Numbers (ICANN) - Based in the United States, coordinates IP address allocation, the management of domain names, and assignment of other information used TCP/IP protocols.
        
        Internet Assigned Numbers Authority (IANA) - Responsible for overseeing and managing IP address allocation, domain name management, and protocol identifiers for ICANN.
        
        Other standard organizations have responsibilities for promoting and creating the electronic and communication standards used to deliver the IP packets as electronic signals over a wired or wireless medium.
        
        Institute of Electrical and Electronics Engineers (IEEE, pronounced “I-triple-E”) – Organization of electrical engineering and electronics dedicated to advancing technological innovation and creating standards in a wide area of industries including power and energy, healthcare, telecommunications, and networking. 802.X
        
        Electronic Industries Alliance (EIA) - Best known for its standards related to electrical wiring, connectors, and the 19-inch racks used to mount networking equipment. EIA/TIA 568-B
        
        Telecommunications Industry Association (TIA) - Responsible for developing communication standards in a variety of areas including radio equipment, cellular towers, Voice over IP (VoIP) devices, satellite communications, and more. Figure 2 shows an example of an Ethernet cable meeting TIA/EIA standards.
        
        International Telecommunications Union-Telecommunication Standardization Sector (ITU-T) - One of the largest and oldest communication standard organizations. The ITU-T defines standards for video compression, Internet Protocol Television (IPTV), and broadband communications, such as a digital subscriber line (DSL).
- - - - Network layer source and destination addresses - Responsible for delivering the IP packet from the original source to the final destination, either on the same network or to a remote network.
        
        An IP address is the network layer, or Layer 3, logical address used to deliver the IP packet
        
        An IP address contains two parts
        
        Network portion – The left-most part of the address that indicates which network the IP address is a member.
        
        All devices on the same network will have the same network portion of the address.
        
        The subnet mask is used to identify the network portion of an address from the host portion.
        
        Host portion – The remaining part of the address that identifies a specific device on the network.
        
        The host portion is unique for each device on the network.
        
        e.g. ip add: 192.168.0.3 /24
        /23 = subnet mask = 24 bits of network portion= 11111111.11111111.11111111.00000000
        192.168.0.3 = 11000000.10101000.00000000.00000011
        The first 24 bits of the ip address are equal to the network portion:
        11000000.10101000.00000000.00000011 = 192.168.0.0
        the rest of the bits are for the host portion: 8 bits for host portion
      - Data link layer source and destination addresses – Responsible for delivering the data link frame from one network interface card (NIC) to another NIC on the same network.
        
        A Media Access Control (MAC) address or physical address, is the address of the device’s NIC.
        MAC addresses are physically embedded on the Ethernet NIC
        
        A MAC address is composed of 12 hexadecimal numbers separated in pairs by a dash: 11-22-33-AA-BB-CC, the first 6 digits represent the brand of the NIC (OUI, organizational Unique Identifier)