Packet switching | Packet switched network | Switching technology | TechTerms

Summary

This script explores the concept of network applications and packet switching, detailing how data is divided into packets and transmitted over the internet via routers. It explains the process of Store-and-Forward transmission, end-to-end delay calculations, and the potential for queuing delays and packet loss. The role of IP addresses and forwarding tables in directing packets to their destination is also highlighted, along with the automatic updating of forwarding tables through routing protocols, providing a comprehensive overview of data transmission in computer networks.

Takeaways

• 🌐 Network applications like Google Chrome, Skype, and Outlook require an Internet connection to operate and exchange data such as images, audio, video, or text files.
• 📦 Data is divided into small units called packets, typically 1 MB in size, for transmission over the Internet.
• 🔄 Packet switching is the method where data packets are transmitted over a network of packet switches, which can be routers or link-layer switches.
• 🚀 Store-and-Forward transmission involves storing the entire packet at the switch before forwarding it to the next destination.
• ⏱️ Propagation delay is the time it takes for a bit to travel from the sender to the receiver, which is 3 ms in the example provided.
• 🕒 The total end-to-end delay for transmitting a packet includes the time taken to send the packet and any additional delays due to the number of links.
• 🔗 The delay for receiving the first packet is 2L/R seconds, and for multiple packets, the formula is (N+(P-1))L/R seconds, where N is the number of links and P is the number of packets.
• 📈 Queuing delay occurs when packets wait in a buffer due to the router's transmission rate being exceeded or other packets being sent.
• 🚫 Packet loss happens when the buffer is full, and incoming packets cannot be stored, leading to data being dropped.
• 📍 IP addresses are unique identifiers for devices on the Internet, and routers use forwarding tables to determine where to send incoming packets.
• 🔄 Forwarding tables are updated automatically through routing protocols to ensure efficient packet routing.

Q & A

What are network applications and why do they require the Internet?

Network applications, such as Google Chrome, Skype, and Outlook, are programs that rely on the Internet to function. They require the Internet because they need to send data, such as images, audio, video, or text files, between end systems or hosts over the network.

What is the purpose of dividing data into packets in network applications?

Data is divided into packets to efficiently manage the transmission over the network. This method allows for the data to be sent in small, manageable units, improving the overall network performance and reliability.

Can you explain the concept of packet switching?

Packet switching is a method of data transmission over a network where data is broken down into small packets. These packets are then routed through a network of packet switches, such as routers or link-layer switches, to reach their destination.

What is Store-and-Forward transmission and why is it used?

Store-and-Forward transmission is a technique where a packet switch, such as a router, must receive the entire packet before it can forward it to the next destination. It is used to ensure that the integrity of the data is maintained during transmission.

How is the propagation delay defined and what factors affect it?

Propagation delay is the time it takes for a signal to travel from the sender to the receiver over a communication link. It is affected by the distance the signal travels and the speed of light in the medium.

What is the formula for calculating the total end-to-end delay for transmitting packets?

The total end-to-end delay for transmitting packets is calculated using the formula {N+(P-1)}L/R, where N is the number of links, P is the number of packets, L is the number of bits in each packet, and R is the transmission rate in bits per second.

What causes queuing delay and how does it affect packet transmission?

Queuing delay occurs when packets must wait in a buffer at a router before being transmitted, due to the router being busy with other transmissions. It affects packet transmission by introducing additional waiting time, which can lead to delays in data delivery.

What is packet loss and how does it occur in a network?

Packet loss occurs when a packet is dropped either because the buffer in the router is full or due to other network issues. It can disrupt the flow of data and lead to incomplete or corrupted transmissions.

How do routers determine the correct communication link to forward a packet?

Routers use forwarding tables to determine the correct communication link to forward a packet. These tables map the destination address prefix to the router's link interface, allowing the router to match the packet's destination address and forward it appropriately.

What is the role of IP addresses in packet switching?

IP addresses are unique identifiers for devices on the Internet. They are used in packet switching to maintain the destination address in the packet header, which helps routers determine the correct path for the packet to reach its destination.

How are forwarding tables in routers updated?

Forwarding tables in routers are updated automatically with the help of routing protocols. These protocols enable routers to exchange information about network topology and update their tables accordingly to ensure efficient routing of packets.