Network Protocols and Communication

Network Protocols and Communication

• This chapter covers network protocols and communication
• Rules facilitate communication by providing a common method
• Protocols and standards organizations ensure interoperability in network communication
• Protocols are necessary for successful communication due to their defined rules and formats
• Protocols define message encoding, delivery options (unicast, multicast, broadcast), formatting, encapsulation, timing, and size
• Encoding converts data to a suitable format for transmission

Rules of Communication

• Communication methods share three common elements: source, destination, and channel (or media).
• Rules or protocols govern all communication methods.

Rule Establishment

• Protocols are needed for effective communication:
  • Identified sender and receiver
  • Common language and grammar
  • Speed and timing of delivery
  • Confirmation or acknowledgment requirements
• Protocols in network communications
  • Define message encoding (converting data to an appropriate form)
  • Establish message delivery options (unicast, multicast, broadcast)
  • Specify message formatting and encapsulation details
  • Define message timing (access methods, flow control)
  • Specify message size limits and potential breakdown of long messages

Message Encoding

• Encoding converts data format to appropriate format for transfer across the network
• Encoding involves conversion of bits to patterns of sounds, light waves, or electrical impulses, depending on the network medium
• Destination host decodes the signals to interpret the message

Message Formatting and Encapsulation

• Agreed letter formatting and addressing is required for proper transmission
• Encapsulation involves placing a letter in the addressed envelope
• Computer messages, packaged in a specific format called frame
• Frames act like envelopes, carrying destination and source addresses

Message Size

• Humans break down long messages into smaller parts (sentences) for clearer communication.
• Long messages are divided into smaller pieces (frames) for effective network transmission
• Each frame carries its own addressing to ensure proper delivery

Message Timing

• Network devices need to know when to begin sending messages and handle potential collisions
• Flow control ensures the receiver is not overwhelmed with data
• Response timeout mechanisms define wait periods for responses and specify actions upon timeouts

Message Delivery Options

• Unicast: One-to-one delivery
• Multicast: One-to-many delivery
• Broadcast: One-to-all delivery

Network Protocols and Standards

• Protocols are implemented in hosts and networking devices using software, hardware, or both
• Protocols are layered, and each higher layer depends on lower layer functions
• A protocol suite defines how the communication elements work together

Network Protocols

• Common protocols, such as HTTP, TCP, and IP, are crucial for managing the processes related to communication
• Hypertext Transfer Protocol (HTTP) manages client-server interactions over the internet
• Transmission Control Protocol (TCP) controls and manages the conversations
• Internet Protocol (IP) creates packets, assigns addresses, and delivers the packets to destination hosts

Protocols Interaction

• HTTP manages application-layer communications between web browsers and servers
• TCP manages the individual conversations involved
• IP encapsulates TCP segments into packets and delivers the packets to destination hosts
• Ethernet allows communication over network media

TCP/IP Protocol Suite

• The TCP/IP protocol suite describes the protocols involved, such as protocols for name system (DNS), host configuration (BOOTP, DHCP), email (SMTP, POP, IMAP), file transfer (FTP, TFTP), and web (HTTP)
• TCP/IP protocols are used for network services, including addressing and routing
• TCP/IP Protocols include UDP for support, and IP on the internet layer such protocols like Routing(OSPF, EIGRP) and ICMP for addressing

TCP/IP Communication Process

• The webserver forms the HTML page and the HTTP application protocol sends to the next layer
• The transport layer breaks the data into segments and identifies each
• The IP source and destination addresses are included in an IP packet
• An Ethernet frame (data link frame) is created using Ethernet information (addressing)

TCP/IP Communication Process (Cont.)

• When receiving data, the Ethernet header is removed, followed by the IP header, and then the Transport header
• Finally, the HTTP information is processed and prepared for the client’s web browser

OSI Model and TCP/IP Model Comparison

• The comparison outlines the differences between the two models, with the OSI model offering a granular view of the layers while the TCP Model provides a higher level view

Data Transfer in the Network

• Large data streams are split into smaller, manageable pieces for transmission
• Segmentation facilitates easier network transmission, allowing processing of multiple conversations at once
• Each data piece (segment) is labeled to allow for re-assembly by the recipient

Protocol Data Units

• Data segments, packets, and frames are protocol data units (PDUs).
• Each layer adds headers and trailers to PDUs for communication, which are removed at the receiving end in an order opposite to the transmission

Encapsulation Example

• The encapsulation process starts at the highest protocol layer, with data being divided into smaller segments
• Segments are encapsulated in IP packets
• IP packets are encapsulated into Ethernet frames (data link layer frames) for transmission

De-encapsulation

• De-encapsulation is the deconstruction of data frames
• The receiving device removes layers of a deconstructed frame.
• The data is de-encapsulated in the order opposite of the encapsulation

Network Addresses

• Network layer addresses (IP addresses) are for delivering packets
• Source IP address refers to the sender (original source of the packet)
• Destination IP refers to the IP address of the receiver (final destination of the packet)

Data Link Addresses

• Data link addresses (MAC addresses) are used to navigate within a network
• As IP packets travel, each router adds a new data link frame

Devices on the Same Network

• Devices on the same network use MAC addresses for local communication
• MAC addresses identify specific devices on a network

Devices on a Remote Network

• Remote network communication involves IP addresses to identify remote devices
• Data link frames are forwarded to the default gateway (nearest router)
• Routers remove or modify part of the data link and add new header information before sending to the final destination

Standards Organizations

• Open standards promote interoperability, competition, and innovation in computer networks.
• Standards organizations, such as the IEEE, IANA, and ITU, define and promote standards.