Networking Protocols and Models

Module Objectives

• Module focuses on protocols and models in networking
• Goal is to explain how network protocols enable device access to local and remote network resources
• Topics include rules for communication, protocols, protocol suites, and the roles of standards organizations
• Also covers use of TCP/IP and OSI models, data encapsulation, and network data access

The Rules

• Networks vary in size/complexity, requiring devices to agree on how to communicate
• Three key elements in communication: source, destination, and communication channel/media
• Protocols govern all communications and dictate the rules to be followed
• Individuals need established rules or agreements to converse effectively
• Protocols must cover: identifying sender/receiver, language, speed, timing, acknowledgment
• Common computer protocols are needed for message encoding, formatting, size, timing, delivery options
• Encoding converts data to an acceptable form for transmission
• Decoding reverses the encoding process for data interpretation
• Messages need a specific format or structure, dependent on message type and communication channel used
• Messages sent over a network convert into bits
• Bits encode to light/sound/electrical impulses, requiring destination hosts to decode the signals
• Message timing includes: flow control, response timeout, and access method
• Flow control manages data transmission rate
• Response timeout manages the wait time for a destination reply
• Access method determines message sending method
• Protocol implementation can be proactive to prevent collisions or reactive to implement a recovery
• Message delivery can be achieved via: Unicast (one-to-one), Multicast (one-to-many), or Broadcast (one-to-all)
• Broadcasts are for IPv4, Anycast delivery option for IPv6

Protocols

• Network protocols follow a common set of rules for communication, can be implemented in software/hardware
• Protocols dictate function, format, and rules for communication
• Protocols facilitate activities like network communication, security, routing, and service discovery
• Addressing identifies the sender and receiver
• Reliability provides guaranteed delivery
• Flow control ensures efficient data flow
• Sequencing uniquely labels transmitted data
• Error detection determines data corruption during transmission
• Application interface manages process-to-process communications over a network
• Hypertext Transfer Protocol governs web server/client interactions and defines format and content of data
• Transmission Control Protocol manages individual conversations, providing guaranteed delivery and flow control
• Internet Protocol delivers messages globally from sender to receiver
• Ethernet delivers messages between network interface cards on the same LAN

Protocol Suites

• Protocols operate with other protocols
• A protocol suite constitutes the group of inter-related protocols necessary to perform a communication function
• Protocol suites help solve problems thru a set of rules
• Protocols operate with higher or lower layers
• Higher layers moves data
• Lower layers concern is with moving data, providing services to upper layers
• Examples include the Internet Protocol Suite (TCP/IP), Open Systems Interconnection (OSI) protocols, AppleTalk, and Novell NetWare
• Transmission Control Protocol/Internet Protocol protocols run at the application, transport, and internet layers
• LAN protocols at the network access layer include Ethernet and Wireless LAN

The TCP/IP Protocol Suite

• TCP/IP suite is used to communicate by the internet
• It inlcudes many protocols
• Open standard protocol suite is available to the public and can be used by any vendor
• This standard's are endorsed by firms in the networking industry and approved by standards organizations
• Web servers encapsulate content being sent to clients
• Clients de-encapsulate content that comes from the web server to a web browser

Standards Organizations

• Encourages interoperability, competition, innovation
• Standards Organizations operate as vendor-neutral and non-profit organizations
• The Internet Society promotes open development and evolution of the internet
• Internet Architecture Board manages development of internet standards
• Internet Engineering Task Force develops, updates, and maintains internet and TCP/IP technologies
• Internet Research Task Force researches internet and TCP/IP protocols
• Internet Corporation for Assigned Names and Numbers coordinates IP address allocation and domain name management
• Internet Assigned Numbers Authority oversees/manages IP address & domain name allocation and also manages identifiers for ICANN
• Institute of Electrical and Electronics Engineers creates standards in energy, healthcare, telecommunications, and networking
• Electronic Industries Alliance develops regulations for electrical wiring and connectors
• Telecommunications Industry Association develops communication standards for radio equipment, cell towers, VoIP, and satellite communication
• the International Telecommunications Union-Telecommunication Standardization Sector defines communication standards for video and IPTV

Reference Models

• Layered models simplify complex network operations
• Main models used for describing network operations include TCP/IP and OSI
• Benefits of layered models include: protocol design assistance, promotes competition among vendors, and prevent technology changes in one layer from affecting another
• Models also provide a shared language to describe networking functions
• Contains communication protocols used for process-to-process communications
• Provides common representation of transferred data between services
• It defines services to segment, transfer, reassemble data for the individual communications
• OSI model contains Application, Presentation, Session, Transport, Network, Data Link, Physical
• TCP/IP Reference contains Application, Transport, Internet, and Network Access
• The OSI model divides layers of Application, Presentation, and Session
• TCP/IP protocol suite does not specify when transmitting the protocols over a physical medium
• OSI Layers 1 and 2 contains steps to access media, also by physical means

Data Encapsulation

• Ensures faster and more efficient network comms
• Segmenting large messages into smaller unit increases efficiencies
• Multiple streams are combined by Multiplexing multiple data streams
• Sequencing numbers data segments so that it can be accurately re-assembled
• Transmission Control Protocol is responsible for this step
• Encapsulation is where protocols add information to the data based on process. PDU acronym name is based on its functions
• Universal naming is not conventional for PDUs
• Data(Data Stream) -> Segment -> Packet -> Frame -> Bits(Bit Stream)
• Encapsulation is a top down stream, Level above do process
• De-encapsulation involves stripping protocol headers as data moves up the stack for processing

Data Access

• Delivers information from source to destination using network and data link layers
• Network layer provides IP packets origin to destination
• Data layer source delivers data link interface cards between NICs within same network
• The IP packet contains source (sending) & destination (receiving)
• Those addresses can be the same link or remote
• IP address uses network & host portions IPv4 or IPv6
• LAN or WAN will have the same network portion
• The remaining part identifies the device or unique portion on the network
• On the same network source & destination will have the same in network portion
• Devices embedded on the NIC with the Data link layer
• Source addresses are located on the originator device
• Destination are located on the same link as the source

Devices on a Remote Network

• 3 questions addresses on a remote network
• What happens to the destination on a remote location?
• How does the PC1 tries to communicate to a web server?
• Network and data link layers are impacted
• Source & destination have different networks, which means the source & destination are on "different" networks
• Layer 3 uses Layer 2 to get to default address