ITT300 - Chapter 2

Peer-to-Peer Process

• Communication at the physical layer transmits a stream of bits from one device (A) to another (B), moving through the OSI layers.
• Each OSI layer has specific functions:
  • Layers 1-3 address physical data movement.
  • Layer 4 (Transport) formats the data for upper layers.
  • Layers 5-7 allow interoperability among different software systems.

OSI Model Layers Organization

• The OSI model has seven layers that process data sequentially from layer 7 (Application) to layer 1 (Physical).
• At each layer, headers or trailers may be added to the data unit to encapsulate addressing and control information.
• At the destination, data is processed upwards through the OSI layers, stripping headers/trailers until reaching application format.

Physical Layer

• Responsible for transmitting individual bits between nodes, utilizing physical media (e.g., LAN/Wi-Fi).
• It defines mechanical and electrical specifications for transmission interfaces and media.
• Key responsibilities include:
  • Physical characteristics of transmission media and interfaces.
  • Representation of bits through encoding (transforming 0s and 1s to signals).
  • Data rate determines how many bits are sent per second.
  • Synchronization ensures sender and receiver clocks are aligned.
  • Physical topology categorizes network connections (e.g., mesh, star).
  • Transmission modes determine data flow direction (simplex, half-duplex, full-duplex).

Data Link Layer

• Ensures error-free delivery of frames from one node to another and manages node-to-node communication.
• It processes incoming data units by adding headers (addresses) and trailers (control info).
• Additional responsibilities include:
  • Framing manages streams of bits into frames.
  • Physical addressing assigns sender and receiver addresses.
  • Flow control regulates data flow to prevent overflow.
  • Error control detects and retransmits lost or damaged frames.
  • Access control manages device communication on shared links.

Network Layer

• Manages packet delivery from source to destination across interconnected networks.
• Provides two critical services:
  • Switching establishes temporary connections between physical links.
  • Routing selects optimal data paths for packet transfer.
• Logical addressing distinguishes source and destination systems across networks.

Transport Layer

• Facilitates process-to-process delivery, ensuring entire messages are intact and in order.
• Establishes connections between applications on different hosts.
• Key functions include:
  • Service-point addressing routes messages to the correct application.
  • Segmentation splits messages into manageable pieces for transmission.
  • Connection control and flow control manage data transmission rates and integrity.

Session Layer

• Manages dialog control and synchronization between systems.
• Ensures consistent interaction through establishing and maintaining communication sessions.

Presentation Layer

• Handles data formatting, translation, encryption, and compression for interoperability between different encoding systems.
• Responsible for converting data into suitable formats before transmission.

Application Layer

• Provides user access to network services, including file transfer, email, and remote login.
• Functions as the interface for end-users or software accessing network applications.

TCP/IP Protocol Suite

• A 5-layer model (Physical, Data Link, Network, Transport, Application) developed prior to the OSI model.
• The top three OSI layers are combined into a single Application layer in TCP/IP.
• TCP/IP serves as the dominant protocol suite, extensively used in internet communications.

Addressing in TCP/IP

• Four address levels are utilized:
  • Physical Address (Link/MAC address) identifies nodes at the hardware level.
  • Logical Address (IP address) provides a universal addressing system to uniquely identify hosts independent of the network.
  • Port Address identifies specific processes on a host, typically 16 bits.
  • Specific Addresses cater to user-friendly applications for unique identification.

Address Characteristics

• Physical addresses vary by network types (e.g., Ethernet uses 6-byte addresses).
• Logical addresses are standard 32-bit numbers in IPv4, allowing global uniqueness.
• Port addresses (16 bits) are essential for multi-process communication on hosts.

Explore the concepts of peer-to-peer processes in network communication. This quiz delves into the organization of the layers, including physical, data link, and network layers. Understanding how these layers interact is crucial for grasping network functionality.