HW1: TCP/IP Overview

Application layer

Consists of a wide variety of user applications. Prominent examples are HTTP, telnet and FTP.

Transport layer

Provides data transport for the application layer. It can provide additional functionalities such as reliable transmission and error detection and correction. Prominent protocols at this layer are TCP and UDP.

Network layer

Handles routing of packets across the network. Prominent protocols at this layer are IP and ICMP.

Data link layer

Handles all the hardware details to provide data transmission for the network layer. Examples protocols: Ethernet, WiFi, PPP.

Internetworking Devices

• A host implements protocols and processes headers up to and including the application layer.
  • Application layer, Transport layer, Network layer, Link layer, Physical layer
• A router implements protocols and processes headers up to and including the network layer.
  • Network layer, Link layer, Physical layer
• A link layer switch (bridge) implements protocols and processes headers up to and including the data link layer.
  • Link layer, Physical layer
• A hub or an Ethernet segment only implements the physical layer.
  • Physical layer

Graphical representation of protocol data units

1. Application Layer

   Data segment: Application data

2. Transport Layer

   TCP segment: TCP header + Application data

   UDP segment: ****UDP header + Application data

3. Network Layer

   IP datagram: **** IP header + TCP header + Application data

4. Datalink Layer

   Ethernet frame: Ethernet header + IP header + TCP header + Application data + Ethernet trailer

   WiFi frame: **** WiFi header + IP header + TCP header + Application data + WiFi trailer

5. Physical Layer