Protocol Layers and Network Models

Packet Switches

• Forward data packets between networks.
• Determine the best route for data packets to reach their destination..

Networks

• A collection of devices (e.g., computers, routers, switches) connected by communication links.
• Enables communication and data sharing between devices.

Communication Links

• Physical pathways for data transmission.
• Examples include cables, wireless signals, and optical fibers.
• Not a communication link: protocols.

Bandwidth

• The capacity or rate of data transmission over a communication link.
• Measured in bits per second (bps).
• Higher bandwidth means faster data transfer.

Hosts

• End devices connected to the network.
• Examples include computers, smartphones, and servers.
• Initiate and receive data transmissions.

Home Network Connections

• Commonly used: DSL, cable, fiber optic, and wireless.

Access Network Characteristics

• Key considerations: bandwidth, latency, cost, and service quality.

Access Networks for Institutions

• Schools and companies: Fiber optic, dedicated lines, and private networks.

Shared vs. Dedicated Access

• Shared: Multiple users share the same link, bandwidth is divided.
• Dedicated: A single user has exclusive use of the link, providing higher bandwidth.

First Point of Connectivity

• Access network: Typically the first point of connectivity for end systems.

Interconnected ISPs

• Internet: An interconnected system made up of millions of Internet Service Providers (ISPs).
• ISPs connect with each other to exchange data.

Integrating ISPs

• Key question: How to effectively connect and manage communication between all ISPs.

Access ISP Role

• Provides internet access to end users.
• Connects users to the broader internet.

Access in Internet Structure

• Access: Refers to the connection between end users and their ISPs.

Connecting ISPs

• Challenge: Connecting millions of ISPs efficiently and reliably.

Message Management Protocol

• Protocol: A set of rules and procedures for communication.
• Example: TCP/IP (Transmission Control Protocol/Internet Protocol).

Internet

• A global network of networks.
• Connects billions of devices worldwide.
• Allows information sharing and communication.

Internet Standards

• Internet Engineering Task Force (IETF): Establishes internet standards and protocols.

Services NOT Offered by the Internet

• Example: Personal face-to-face communication.

Content Provider Purpose

• Delivers content and services to internet users.
• Examples include websites, streaming platforms, and social media services.

Mobile Networks

• Mobile networks are synonymous with cellular networks.
• Allow devices to access the internet wirelessly.

Interface for Application Connectivity

• Application Programming Interface (API): Allows applications to interact and exchange data with internet services.

Local Network

• Local Area Network (LAN): Connects devices within a single location (e.g., home, office).

ISP Role in Internet Architecture

• Provides access to the internet for individuals and businesses.
• Connects user networks to the broader internet.

Establishing Connections

• Routers: Essential for establishing connections between various networks.

Connecting Access Networks to ISPs

• Backbone networks: Connect access networks to ISPs.

National and International ISPs

• Tier 1 ISPs: National and international coverage, often with multiple backbone networks.

Content Provider Network Design

• Deliver content quickly and efficiently to users.
• Connect data centers to each other and to the broader internet.

Network Structure Components

• Not a component: Content provider networks (CPNs).

Bypassing Content Provider Networks

• CPNs may bypass backbone networks to improve speed and efficiency for their content delivery.

Access Networks and ISPs

• Access networks provide connectivity to ISPs.
• ISPs provide access to the internet for end users.

Network Traffic Exchange

• Peer-to-peer link: Allows two networks to exchange traffic directly.

Well-Connected Networks

• Large networks in the center of the internet structure: Often represent major ISPs and data centers.

Organizing Networks

• Challenge: Effectively organizing and connecting the diverse network structure.

Access Network Role

• Provides initial internet access for end users.

Local Internet Service Provider (ISP)

• Operates locally: Provides internet access in a limited geographic area.

Content Provider Network Characteristics

• Optimized for content delivery: High bandwidth and low latency connections.

Data Exchange Between ISPs

• Peering: Allows ISPs to exchange data without intermediaries.

Internet Organizational Structure

• Decentralized: No central authority controls the internet.
• Collaboration and consensus drives standards and protocols.