Packet Switching Techniques

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Questions and Answers

What is the primary function of a router in the network layer?

Forwarding a packet by examining the packet's header field and using the header field value to index into the forwarding table.

What is the process of moving data from one device to another device called?

Routing

What is the mechanism called where a packet is stored at a router until it has fully arrived, verified by a checksum, and then forwarded to the next router?

Store and Forward packet switching

What is the term for breaking packets into the smallest individual data units that travel through different networks?

Fragmentation Signup and view all the answers

What is the process called when a router forwards a packet from an entry interface to an exit interface?

Forwarding Signup and view all the answers

What is the process of finding the best possible route for packet transmission called?

Routing Signup and view all the answers

What is the primary condition for sending an acknowledgment message in packet switching?

Reaching the correct order of the packets Signup and view all the answers

What is the advantage of packet switching in terms of storage requirement in switching devices?

They don't require massive storage Signup and view all the answers

How does packet switching ensure better bandwidth usage?

By transferring packets from multiple sources via the same link Signup and view all the answers

What is the primary limitation of packet switching in terms of applications?

Unsuitability for applications that cannot afford delays in communication Signup and view all the answers

What is the characteristic of datagram packet switching that makes it 'connectionless'?

Each packet is considered as an independent entity Signup and view all the answers

What is the potential drawback of packet switching in terms of packet delivery?

Errors, delay, or loss of packets due to network problems Signup and view all the answers

What is the advantage of message switching in terms of data size?

It supports data of unlimited size. Signup and view all the answers

What is the purpose of packet sequencing in packet switching?

To reassemble the packets in the correct order at the receiving end. Signup and view all the answers

What happens when a packet is missing or corrupted in packet switching?

The message is resent. Signup and view all the answers

How do packets travel across the network in packet switching?

They take the shortest path possible. Signup and view all the answers

What information is included in the headers of packets in packet switching?

Source address, destination address, and sequence number. Signup and view all the answers

Why is message switching not suitable for real-time applications?

Because it is slow due to the store-and-forward technique and waits until resources are available. Signup and view all the answers

Study Notes

Fragmentation

Fragmentation is a process of breaking packets into the smallest individual data units that travel through different networks.

Network Layer Services

Forwarding: a router forwards a packet by examining a packet's header field and then using the header field value to index into the forwarding table.
Routing: the process of moving data from one device to another device, finding the best possible route.
Packet forwarding: the action applied by each router when a packet arrives at one of its interfaces.

Network Layer Design Issues

Store and Forward packet switching: a mechanism where the host sends the packet to the nearest router, which stores it until it has fully arrived, verifies the checksum, and then forwards it to the next router until it reaches the destination.
Packet switching involves packet forwarding from an entry interface out to an exit interface.

Packet Switching Techniques

There are two approaches to Packet Switching: Datagram Packet switching and Virtual Circuit Switching.

Advantages of Packet Switching

Delay in delivery of packets is less, since packets are sent as soon as they are available.
Switching devices don’t require massive storage, since they don’t have to store the entire messages before forwarding them to the next node.
Data delivery can continue even if some parts of the network faces link failure.
Packets can be routed via other paths.
It allows simultaneous usage of the same channel by multiple users.
It ensures better bandwidth usage as a number of packets from multiple sources can be transferred via the same link.

Disadvantages of Packet Switching

Unsuitable for applications that cannot afford delays in communication like high-quality voice calls.
High installation costs.
Requires complex protocols for delivery.
Network problems may introduce errors in packets, delay in delivery of packets, or loss of packets.

Datagram Packet Switching

A packet switching technology in which packet is known as a datagram, is considered as an independent entity.
Also known as connectionless switching.
Traffic congestion can be reduced because the message is temporarily stored in the nodes.
Message priority can be used to manage the network.
The size of the message which is sent over the network can be varied.
Supports the data of unlimited size.

Disadvantages of Datagram Packet Switching

Every switch in transit path needs enough storage to accommodate entire message.
Message switching is very slow due to the store-and-forward technique and waits until resources are available.
Not a solution for streaming media and real-time applications.

Packet Switching Techniques

In packet switching, the message is sent in one go, but it is divided into smaller pieces, known as packets, and they are sent individually.
Packets are given a unique number to identify their order at the receiving end.
Every packet contains some information in its headers such as source address, destination address, and sequence number.
Packets travel across the network, taking the shortest path as possible.
All the packets are reassembled at the receiving end in correct order.
If any packet is missing or corrupted, the message will be sent to resend the message.

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Description

This quiz covers the basics of packet switching, including datagram and virtual circuit switching, as well as the advantages of packet switching such as reduced delay and minimal storage requirements.