Week 2: Network and Internet Protocol

  • Source: Computer Networking: A Top-Down Approach, 8th edition by Jim Kurose, Keith Ross, Pearson, 2020

Today's Agenda

  1. Introduction to Protocols

  2. Two Internet Protocol Standards

Introduction to Protocols

  • Definition of Protocol:

    • In network communications, a protocol is defined as an agreement between communicating parties on how a conversation will take place. It establishes the rules for communication, making them essential before any interaction occurs.

Conversation Rules

  • Implicit rules exist among friends.

  • More formal situations provide explicit rules at the start.

  • Uncertainty may arise in new situations regarding the rules.

  • The rules depend on the conversation type and social context.

  • Disregarding rules can lead to ineffective communication.

Types of Protocols

Communication Protocols

  • Connection-oriented:

    • Establishes a dedicated connection between devices prior to data transmission.

    • Maintains the connection throughout communication until termination.

  • Connectionless:

    • Transmits data packets independently without establishing a dedicated connection.

    • Each packet is sent as an independent unit.

Categories of Protocols

  • Network Communication Protocols

  • Network Security Protocols

  • Network Management Protocols

Network Communication Protocols

Key Protocols:

  1. Transmission Control Protocol (TCP)

    • Chunks data into packets for secure and efficient transmission while minimizing data loss.

    • Ensures correct and ordered delivery without errors.

    • Analogy: TCP resembles sending registered mail, where each delivery is tracked and confirmed.

  2. Internet Protocol (IP)

    • Addresses data packets and encapsulates them with address headers containing sender and recipient information.

    • No concern for the order of packets; it does not guarantee packet delivery.

    • Analogy: IP is akin to a postal service delivering letters without ensuring they arrive or are appointed in order.

  3. User Datagram Protocol (UDP)

    • A connectionless protocol focusing on low latency.

    • Ideal for real-time services like gaming, voice, and video communications where performance matters.

    • Allows packet drops instead of delays, with no error checking to save bandwidth.

  4. Hypertext Transfer Protocol (HTTP)

    • Utilizes TCP/IP for delivering web page content from servers to browsers.

    • Handles file upload/download from remote servers.

  5. File Transfer Protocol (FTP)

    • Facilitates file transfers between computers over a network.

    • Primarily used for uploading files to servers, though downloading can also occur.

  6. Email Protocols:

    • Post Office Protocol 3 (POP3):

      • Allows email clients to receive emails, typically downloading and deleting them from the server.

    • Simple Mail Transfer Protocol (SMTP):

      • Used to send emails from a client to a server or between servers.

    • Internet Message Access Protocol (IMAP):

      • Offers powerful capabilities for managing emails from an email server, allowing synchronization across multiple devices.

Email Protocol Functionality:

  • POP3:

    • Downloads emails to local devices, not suitable for multi-device synchronization.

  • SMTP:

    • Manages outgoing emails only.

  • IMAP:

    • Keeps emails on the server, enabling synchronization and collaborative actions across devices.

Network Security Protocols

Key Protocols:

  1. Secure Socket Layer (SSL)

    • An encryption and security protocol providing secure connections by encrypting communications.

    • Employs public-key cryptography and digital certificates for authentication.

    • Largely replaced by TLS (Transport Layer Security).

  2. Transport Layer Security (TLS)

    • Successor to SSL, offering a stronger and more robust security encryption protocol.

    • Protects against message forgery, tampering, and eavesdropping.

  3. Hypertext Transfer Protocol Secure (HTTPS)

    • Combines HTTP and SSL/TLS for secure web communication, ideal for sensitive data transmissions.

    • Identified by starting with "https://".

  4. Secure Shell (SSH)

    • Provides a secure data connection for remote access, file transfer, and creating secure tunnels.

    • Widely used by IT professionals and cloud services for server management and secure access.

  5. Kerberos

    • Robust authentication for client-server applications via secret-key cryptography, assuming all endpoints are insecure.

Network Management Protocols

Overview:

  1. Simple Network Management Protocol (SNMP)

    • An internet protocol for collecting data from and managing devices on a network (e.g., routers, switches).

  2. Internet Control Message Protocol (ICMP)

    • Enables warning and error messages to be sent among networked devices, providing operational status information.

    • Not intended for data transmission; rather for connectivity feedback.

How Network Protocols Work

  • Developed according to industry standards set by various organizations including IETF, IEEE, ISO, ITU, and W3C.

Protocol Architecture

  • Communication tasks are modular and layered for efficiency.

Standardized Protocol Architecture:

  • Ensures devices can communicate and allows customers to expect standards-compliant equipment.

  • Two main standards:

    • OSI (Open System Interconnection) Reference Model

    • TCP/IP Protocol Stack

OSI Reference Model

  • An internationally standardized network architecture, consisting of 7 layers:

    1. Application Layer

    2. Presentation Layer

    3. Session Layer

    4. Transport Layer

    5. Network Layer

    6. Data Link Layer

    7. Physical Layer

Physical Layer Details

  • Involves mechanical, electrical, and timing issues, defined by protocols such as IEEE 802 series, governing data types as bits.

  • Devices include transmission media (e.g., fiber optic cables).

Data Link Layer

  • Responsible for communication between adjacent nodes, divided into two sublayers:

    • Media Access Control (MAC)

    • Logical Link Control (LLC)

Network Layer

  • Establishes paths for data transfer (routing), translating logical addresses into physical addresses.

  • Data is structured in packets including headers for addressing.

Transport Layer

  • Delivers messages between hosts, manages segmentation, flow control, and acknowledgment of segments that are not acknowledged.

  • Devices in this layer include routers and gateways.

Session Layer

  • Divides connections into phases: establishment, transfer, and termination.

Presentation Layer

  • Ensures interoperability between different systems through encoding and encryption functions.

Application Layer

  • Provides services such as file transfers, email, and network management, directly interacting with end-users.

TCP/IP Reference Model

  • Consists of 4 layers aligned with high-level protocols:

    • Application

    • Transport

    • Internet

    • Host-to-Network

Summary of Key Takeaways:

  • In-depth exploration of protocols and their functionalities.

  • Examination of the OSI model and TCP/IP stack.

Conclusion

  • Acknowledgment for attending and an invitation for questions.