Let’s Know MoreAbout Packet Switching
What is packet switching?
Packet switching is a networking communication method used in telecommunications systems, whereby data is grouped into blocks called packets and routed through a network using a destination address contained within each packet.
By breaking the communication information down into packets, it allows the same path to be shared among many users in a network. It also means that each packet can take a different route to its destination. This form of connection (between sender and receiver) is known as connectionless (as opposed to dedicated). Regular voice telephone networks are often circuit-switched rather than packet switched; whereby for the duration of the call connection, all the resources on that circuit are unavailable to other users.
Packets
An individual packet is a unit of data which is routed between an origin and a destination via the internet or another packet-switched network.
If a file such as an email, GIF or HTML file is sent via packet-based transmission, the TCP (Transmission Control Protocol) layer of the TCP/IP will divide the file into chunks that are optimised sizes for routing. Each chunk is known as a packet and is separately numbered and carried along with a destination address. The packets may then travel on different routes to the destination, but when they all arrive, they are reassembled into the original format (by the TCP layer at the receiving end).
Every packet contains some information in its headers such as source address, destination address and sequence number Packets will 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, then the message will be sent to resend the message.If the correct order of the packets is reached, then the acknowledgement message will be sent.
Analysis Of Packet Switching
Delay
As there is no dedicated path and there is presence of multiple nodes on the path ,some amount of time is required to process the datagram at each node .If the traffic is more the the time required is more and till then the datagram is in the queue. Packet can travel along different paths so time required to reach the destination for each packet is different .If the distance between source and destination to large and also the propagation delay is to large then there is some delay in the network called propagation delay.If the transforming rate of the router present in the rout is greater than the receiving rate of the next router then that router have the make the packet to wait until the current packet is processed and transferred. This type of delay is called queuing delay. Sometimes the router takes time to process the data over network and this type of delay is called processing delay. In simple words, it is just the time taken to process packets. As the movement of packets is not synchronous in this switching, it may not be suitable in communication applications like voice calls; while circuit switching is highly suitable for voice calls
Reliability
Packet switching is reliable because it helps to eliminate packet loss . With packet switching, data packets can be resent if they don’t reach their destination. This isn’t the case for circuit switching which doesn’t have the means to send lost packets. As a result, packet switching is the more reliable method of the two because it ensures that packets reach their destination.
Data transmission
In this switching technique, the data transmission begins as soon as the data is transmitted from the sender and placed over the network. Here no particular path is assigned for the packets to follow. They can go through any path that is available between to reach to the destination. Now to assemble all the packets in a sequence at receiving end the sender’s OS give the sequence number to each packet in order and at receiver end all these packets are arranged in the same sequence.
Network Performance
Packet Switching uses lesser bandwidth as packets are quickly routed towards the destination; circuit switching should have dedicated bandwidth. The channel in this switching is available for other transmissions as soon as packets are routed; circuit switching occupies the channel till the voice communication is completed.In packet switching, network performance totally depends on the transmitting and receiving speed of the router present between the source and destination. If the bandwidth of network is sufficient then the whole process works smoothly
Error Handling
Packets contain checksum, parity bits or cyclic redundancy checks. These each detect errors that may occur during transmission.A preliminary calculation is performed before the packet is sent, at the transmitter. Once the packet is received, the checksum is recalculated and compared with the first calculation that is contained in the packet. If any discrepancies are noticed the packet can be corrected or discarded. Any discarded information is known as packet loss and will be dealt with by the network protocol.
Implementation
Packet switching is one such technology used nowadays on data networks like the Internet LAN, WAN. The development of Voice over Internet Protocol (VoIP), enabled packet switching to easily transmit data and voice traffic. This allowed businesses to experience huge benefits in terms of cost, efficiency, and scalability .It is well suited to data transmission, as it allows networks to adapt to changing conditions quickly. For example, if one of the network’s router fails, packet can be automatically re-routed to avoid that device.
What is Packet Loss?
Occasionally, packets might bounce from router to router many times before reaching their destination IP address. Enough of these kinds of “lost” data packets in the network can congest it, leading to poor performance. Data packets that bounce around in the network too many times may get lost.The hop count addresses this problem, setting a maximum number of bounce times per packet. “Bouncing” simply refers to the inability to locate the final destination IP address, and the resulting transfer from one router to another instead. If a certain packet reaches its maximum hop count, or maximum number of hops it is permitted before reaching its destination, the router it is bouncing from deletes it. This causes packet loss
Advantages of Packet Switching over Circuit Switching
Efficiency. Improved efficiency means less network bandwidth wastage. No need to reserve the circuit even when it’s not in use means the system is more efficient. A constantly reserved circuit results in wasted network bandwidth, so network efficiency tends to increase with the use of packet switching.
Speed. Optimal transmission speed, minimal latency.
Improved fault tolerance. During partial outages or other network problem times, packets can be rerouted and follow different paths. Using a circuit switching network, a single outage can down the designated pathway for the communications.
Budget. Comparatively cost-effective and simple to implement. Packet switching typically also bills based only on duration of connectivity, whereas circuit switching bills on both duration of connection and distance.
Digital. Packet switching works well for data communication, transmitting digital data directly to its destination. Data transmissions are generally high quality in a packet switched network because such a network employs error detection and checks data distribution with the goal of error free transmissions.
Disadvantages of Packet Switching over Circuit Switching:
Complexity. Packet switching protocols are complex, so switching nodes demand more processing power and a large amount of RAM.
File size. Packet switching is more useful for small messages, while circuit switching is best for larger transmissions. This is due to multiple rerouting delays, the risk of multiple lost packets, and other issues.
Delay: Packet Switching technique cannot be implemented in those applications that require low delay and high-quality services.
Loss of data: If the network is overloaded or corrupted, then it requires retransmission of lost packets. It can also lead to the loss of critical information if errors are nor recovered. However, circuit switched networks deliver packets in order along the same route and are therefore less likely to experience missing packets in the first place.