2.1

Connection-Oriented and Connectionless Protocols

• TCP (Transmission Control Protocol) is a connection-oriented protocol, meaning a connection is established before data is sent.
• UDP (User Datagram Protocol) is a connectionless protocol, meaning no connection is established before data is sent.

Protocol Responsibilities

• TCP is responsible for verifying that data has been received on the other side.
• TCP can reorder messages that were received out of order.
• TCP provides flow control to regulate the flow of communication across the network.

Unreliable Protocols

• UDP is considered unreliable because there is no acknowledgment of received data.

Real-Time Communication

• UDP is most associated with real-time communication and does not require retransmission of information.

IP Address Assignment

• DHCP (Dynamic Host Configuration Protocol) is responsible for automatically assigning IP addresses to devices.

Transport Mechanisms

• DNS (Domain Name System) uses UDP as its transport mechanism for sending information across the network.

Encrypted Communication

• SSH (Secure Shell) provides an encrypted form of terminal communication between systems.

Port Numbers

• Port numbers in TCP and UDP communication identify specific processes or services.
• Port 80 is commonly used for sending unencrypted data in web servers.

Networking Metaphor

• The road in networking is like the Internet, providing a pathway for data to travel.
• The moving truck in the metaphor represents the transport protocol (TCP or UDP).
• The moving truck knows the destination and sequence number of the box (data packet).
• The box represents a unit of data being sent across the network.

Encapsulation

• Encapsulation in networking involves wrapping application data in headers and trailers to ensure proper routing and delivery.

Transport Protocols

• TCP uses well-known port numbers for services.
• UDP has its own set of port numbers that are different from TCP's port numbers.
• Avoid running one service on TCP port 80 and another on UDP port 80 to prevent confusion.

Port Number Ranges

• Destination port number for web server traffic using TCP is 80.
• VoIP traffic commonly uses UDP as its transport protocol.
• Source port number for email traffic using TCP is randomly assigned.
• Non-ephemeral ports range from 1 to 1023, while ephemeral ports range from 1024 to 65535.
• Port numbers are not a security mechanism because they can be easily spoofed or manipulated.

Ephemeral Ports

• The purpose of ephemeral ports is to provide temporary, dynamic port assignment for client-side applications.
• Most services use non-ephemeral or non-temporary port numbers to maintain consistency and organization.