Design Issues in Network Layer

The Network layer is majorly focused on getting packets from the source to the destination, routing error handling, and congestion control. Before learning about design issues in the network layer, let’s learn about its various functions.

• Addressing: Maintains the address at the frame header of both source and destination and performs addressing to detect various devices in the network.
• Packeting: This is performed by Internet Protocol. The network layer converts the packets from its upper layer.
• Routing: It is the most important functionality. The network layer chooses the most relevant and best path for the data transmission from source to destination.
• Inter-networking: It works to deliver a logical connection across multiple devices.

The network layer comes with some design issues that are described as follows:

1. Store and Forward packet switching

The host sends the packet to the nearest router. This packet is stored there until it has fully arrived once the link is fully processed by verifying the checksum then it is forwarded to the next router till it reaches the destination. This mechanism is called “Store and Forward packet switching.”

2. Services provided to the Transport Layer

Through the network/transport layer interface, the network layer transfers its patterns services to the transport layer. These services are described below. But before providing these services to the transfer layer, the following goals must be kept in mind:-

• Offering services must not depend on router technology.
• The transport layer needs to be protected from the type, number, and topology of the available router.
• The network addresses for the transport layer should use uniform numbering patterns, also at LAN and WAN connections.

Based on the connections there are 2 types of services provided :

• Connectionless – The routing and insertion of packets into the subnet are done individually. No added setup is required.
• Connection-Oriented – Subnet must offer reliable service and all the packets must be transmitted over a single route.

3. Implementation of Connectionless Service

Packets are termed as “datagrams” and corresponding subnets as “datagram subnets”. When the message size that has to be transmitted is 4 times the size of the packet, then the network layer divides into 4 packets and transmits each packet to the router via. a few protocols. Each data packet has a destination address and is routed independently irrespective of the packets.

4. Implementation of Connection-Oriented service:

To use a connection-oriented service, first, we establish a connection, use it, and then release it. In connection-oriented services, the data packets are delivered to the receiver in the same order in which they have been sent by the sender. It can be done in either two ways :

• Circuit Switched Connection – A dedicated physical path or a circuit is established between the communicating nodes and then the data stream is transferred.
• Virtual Circuit Switched Connection – The data stream is transferred over a packet switched network, in such a way that it seems to the user that there is a dedicated path from the sender to the receiver. A virtual path is established here. While, other connections may also be using the same path.

Both Connection-less and Connection-Oriented are used for the connection establishment between two or more devices. These types of services are provided by the Network Layer.

Connection-oriented service: In connection-Oriented service we have to establish a connection between sender and receiver before communication. Handshske method is used to establish a connection between sender and receiver. Connection-Oriented service include both connection establishment as well as connection termination phase. Real life example of this service is telephone service, for conversation we have to first establish a connection.

Connection-less service: In Connection-Less service no need of connection establishment and connection termination. This Service does not give a guarantee of reliability. In this service, Packets may follow the different path to reach their destination. Real life examples of this service is postal system, Online gaming, real-time video and audio streaming etc.

What is a design issue?

A design issue typically represents a significant problem that arises from the operational requirements and capabilities of a robotic system. It is a critical element of the design process, often leading to specific design solutions.

What are the design issues in the transport layer?

Design issues of a transport layer are :

• Receive data from the Session layer, divide it into segments, and forward it to the Network layer.
• Guarantee the efficient and accurate delivery of data.
• Shield upper layers from technological changes.
• Manage error control and flow control.

What are the four key design issues of a computer network layer?

Four key design issues of a computer network layer :

• Addressing.
• Packeting.
• Routing.
• Inter-Networking.

How many types of network design are there?

Computer networks are often categorized by their purpose and size. To better understand network classification, explore various types of networks, such as LAN, WAN, WLAN, MAN, and SAN. Additionally, learn about the specific purposes of PAN, EPN, and VPN networks.