Transport protocol is a critical component of computer networks that provides reliable and efficient data transfer between two endpoints. The transport layer is responsible for handling end-to-end communication between applications running on different hosts or devices.
“Computer networks”has two commonly used transport protocols:
TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
- TCP is a connection-oriented protocol that provides reliable, ordered, and error-checked delivery of data between applications. TCP establishes a connection between two endpoints before transmitting data and uses various mechanisms like flow control and congestion control to ensure that data is delivered without loss or corruption.
- UDP, on the other hand, is a connectionless protocol that provides fast, unreliable, and unordered delivery of data. Unlike TCP, UDP does not establish a connection before transmitting data and does not provide any mechanisms for error checking or recovery.
In summary, the transport protocol is an essential component of computer networks that enables reliable and efficient communication between applications running on different hosts or devices.
Working of Transport Protocol
Transport protocols provide end-to-end communication services to applications running on different hosts or devices. Two commonly used transport protocols are Transmission Control Protocol (TCP) and User Datagram Protocol (UDP).
Transmission Control Protocol (TCP)
- Connection Establishment: The sender (client) initiates a connection request to the receiver (server) by sending a SYN (synchronize) packet. The receiver responds with a SYN-ACK (synchronize-acknowledge) packet, acknowledging the request.
- Congestion Control: TCP manages congestion by monitoring the network traffic and adjusting the rate at which data is sent to avoid congestion.
- Error Detection and Correction: TCP uses a checksum mechanism to detect errors in the data transmission. If an error is detected, TCP requests the sender to retransmit the affected segment.
User Datagram Protocol (UDP)
- Data Transmission: Unlike TCP, UDP does not establish a connection before transmitting data. The sender simply sends the data in the form of datagrams to the receiver.
- Error Detection: UDP uses a checksum mechanism to detect errors in the data transmission. However, it does not request retransmission of the affected datagram in case of errors.
- No Flow Control or Congestion Control: UDP does not manage flow control or congestion control. Therefore, it can result in packets being lost or delivered out of order.
- No Connection Termination: since UDP does not establish a connection, there is any need to terminate the connection explicitly.
Responsibilities of a Transport Layer
The transport layer is responsible for ensuring reliable and efficient communication between two hosts (applications) over a network. Some of the key responsibilities of the transport layer are:
- End-to-end communication: The transport layer provides end-to-end communication between two applications by establishing a logical connection between them.
- Error control: The transport layer detects errors in the data transmitted over the network and provides mechanisms to recover lost or corrupted data.
- Flow control: The transport layer regulates the flow of data between two applications to ensure that the receiver is not overwhelmed with data.
- Congestion control: The transport layer manages network congestion by monitoring network traffic and adjusting the transmission rate to avoid network congestion.
- Multiplexing and Demultiplexing: The transport layer enables multiple applications to use the same network connection by multiplexing the data from multiple applications at the sender and demultiplexing it at the receiver.
Advantages and disadvantages of Transport Protocol
- Reliable data transfer: TCP provides reliable data transfer, which means that packets are acknowledged by the receiver and retransmitted if necessary. This helps ensure that data is delivered without errors or losses.
- Flow control: TCP also provides flow control, which means that it regulates the rate at which data is sent to prevent the sender from overwhelming the receiver.
- Congestion control: TCP includes congestion control, which adjusts the rate at which data is sent to avoid network congestion.
- Packet ordering: TCP guarantees that packets are delivered in the order they were sent, which is important for many types of applications.
- Overhead: TCP adds a significant amount of overhead to each packet, which can slow down the transfer of data.
- Latency: TCP's reliability mechanisms can introduce latency, which is the time delay between when a packet is sent and when it is received.
- Limited scalability: TCP's congestion control mechanisms are designed to work well in small networks but can become less effective in larger ones.
UDP doesn't have reliability or flow control features, which can lead to lost or out-of-order packets.
In summary, transport protocols have both advantages and disadvantages. TCP provides reliable data transfer, flow control, congestion control, and packet ordering, but at the cost of overhead and latency. UDP is faster and has lower overhead, but does not provide reliability or flow control. The choice of which protocol to use depends on the requirements of the specific application.