Protocols and Models

• Protocols enable devices to access local and remote network resources by defining a common set of rules that govern communications
• Network protocols are necessary in network communication to establish rules that govern how communications will follow
• Adhering to a protocol suite is important as it ensures that a group of inter-related protocols work together to solve communication problems
• Standards organizations play a crucial role in establishing protocols for network interoperability by developing and promoting open standards
• Adhering to a protocol suite is important as it ensures that a group of inter-related protocols work together to solve communication problems
• Protocols enable devices to access local and remote network resources by defining a common set of rules that govern communications
• Types of rules necessary for successful communication include addressing, reliability, flow control, sequencing, error detection, and application interface
• Protocols are necessary in network communication to establish rules that govern how communications will follow, ensuring effective and standardized data exchange
• Adhering to a protocol suite is essential to ensure that different protocols can work together to solve communication problems efficiently
• Standards organizations play a crucial role in establishing protocols for network interoperability by developing and promoting open standards
• The TCP/IP model and the OSI model facilitate standardization in the communication process by providing a structured framework for data transmission
• Data encapsulation allows data to be transported across the network by enclosing the data in protocol headers as it moves through the network layers
• Local hosts access local resources on a network by following common computer protocols that include message encoding, formatting, size, timing, and delivery options
• Message encoding is the process of converting information into another acceptable form for transmission, while decoding reverses this process to interpret the information
• Message formatting and encapsulation ensure that messages use a specific format or structure depending on the type of message and the delivery channel
• Message timing in network communication includes flow control, response timeout, access method, and various rules to manage issues like collisions
• Message delivery options in network communication can be unicast (one to one), multicast (one to many), or broadcast (one to all)
• Network protocols define a common set of rules that can be implemented in software, hardware, or both, each with specific functions, formats, and rules
• Devices use agreed-upon protocols to communicate, with functions like addressing, reliability, flow control, sequencing, error detection, and application interface
• Networks require the use of several protocols, each with its own function and format, such as HTTP, TCP, IP, and Ethernet
• Protocol suites are groups of inter-related protocols necessary to perform a communication function, viewed in terms of layers for efficient data transmission
• TCP/IP is the most common protocol suite used on the internet, freely available and endorsed by the networking industry for interoperability
• Open standards encourage interoperability, competition, and innovation, promoted by vendor-neutral, non-profit standards organizations
• Standards organizations like ISOC, IAB, IETF, and IANA play key roles in developing and maintaining internet and TCP/IP technologies
• The benefits of using a layered model like the OSI and TCP/IP models include assisting in protocol design, fostering competition, and providing a common language for networking functions
• OSI Model Layers:

  • 7 - Application: Contains protocols used for process-to-process communications
  • 6 - Presentation: Provides a common representation of the data transferred between application layer services
  • 5 - Session: Provides services to the presentation layer and manages data exchange
  • 4 - Transport: Defines services to segment, transfer, and reassemble data for individual communications
  • 3 - Network: Provides services to exchange individual pieces of data over the network
  • 2 - Data Link: Describes methods for exchanging data frames over a common media
  • 1 - Physical: Describes the means to activate, maintain, and de-activate physical connections
• TCP/IP Reference Model Layers:

  • Application: Represents data to the user, plus encoding and dialog control
  • Transport: Supports communication between various devices across diverse networks
  • Internet: Determines the best path through the network
  • Network Access: Controls the hardware devices and media that make up the network
• Data Encapsulation Processes:

  • Segmenting: Breaking up messages into smaller units
  • Multiplexing: Taking multiple streams of segmented data and interleaving them together
• Benefits of Segmenting Messages:

  • Increases speed: Large amounts of data can be sent over the network without tying up a communications link
  • Increases efficiency: Only segments that fail to reach the destination need to be retransmitted, not the entire data stream
• Data Encapsulation Protocol Data Units:

  • Encapsulation is the process where protocols add their information to the data
  • Protocol Data Units (PDUs) passing down the stack are: Data (Data Stream), Segment, Packet, Frame, Bits (Bit Stream)
• Data Access Layer 3 Logical Address:

  • An IP packet contains two IP addresses: Source IP address and Destination IP address
  • Source IP address: The IP address of the sending device, original source of the packet
  • Destination IP address: The IP address of the receiving device, final destination of the packet
• Devices on the Same Network:

  • When devices are on the same network, the source and destination will have the same number in the network portion of the address
• Role of the Data Link Layer Addresses:

  • When devices are on the same Ethernet network, the data link frame will use the actual MAC address of the destination NIC
  • MAC addresses are physically embedded into the Ethernet NIC and are local addressing
• Role of the Data Link Layer Addresses: Different IP Networks:

  • When the final destination is remote, Layer 3 will provide Layer 2 with the local default gateway IP address, also known as the router address
  • The default gateway is the router interface IP address that is part of this LAN and will be the “door” or “gateway” to all other remote locations
• Lab - Install Wireshark:

  • Download and Install Wireshark
• Lab - Use Wireshark to View Network Traffic:

  • Part 1: Capture and Analyze Local ICMP Data in Wireshark
  • Part 2: Capture and Analyze Remote ICMP Data in Wireshark
• Module Practice and Quiz:

  • Protocols must have a sender and a receiver
  • Common computer protocols include message encoding, formatting and encapsulation, size, timing, and delivery options
  • Each network protocol has its own function, format, and rules for communications
• New Terms and Commands:

  • Encoding, protocol, channel, flow control, response timeout, acknowledgement, unicast, multicast, broadcast, protocol suite, Ethernet, standard, proprietary, 802.3 (Ethernet), 802.11 (wireless Ethernet), segmentation, default gateway, HTTP, SMTP, POP, TCP, transport, data link, network access, ARPANET