What are the functions of the Transport layer?

Question

I have a homework question which asks what the four functions of the Transport layer are. It doesn't mean what the functions of TCP or UDP are, but the layer itself.

Answer 1

• Connection-oriented communication
• Byte orientation
• Reliability
• Flow control
• Congestion avoidance

source : http://en.wikipedia.org/wiki/Transport_layer

Answer 2

Some of the functions offered by the transport layer include:

• Application identification
• Client-side entity identification
• Confirmation that the entire message arrived intact
• Segmentation of data for network transport
• Control of data flow to prevent memory overruns
• Establishment and maintenance of both ends of virtual circuits
• Transmission-error detection
• Realignment of segmented data in the correct order on the receiving side
• Multiplexing or sharing of multiple sessions over a single physical link

Answer 3

Transport layer is the 4th layer in TCP/IP Model that deals with logical communication between process.

The several functions of the Transport layer are given below :

1. Network layer provides the segmentation of data.
2. It ensure the process to process delivery.
3. It provides the flow control and error control
4. It can work with not only connection less but also connection oriented transmission.

Answer 4

Transport layer is primarily responsible for reliable process-process communication between host and client. See more here: http://en.wikipedia.org/wiki/Transport_layer

Answer 5

1. segmentation
2. Connection management
3. flow control
4. aknowledgement processing
5. error detection and correction

Answer 6

The primary responsibilities of transport layer protocols are:

• Tracking the individual communication between applications on the source and destination hosts. Each particular set of data flowing between a source application and a destination application is known as a conversation. A host may have multiple applications that are communicating across the network simultaneously. Each of these applications communicates with one or more applications on one or more remote hosts. It is the responsibility of the transport layer to maintain and track these multiple conversations.
• Segmenting data for manageability and reassembling segmented data into streams of application data at the destination. Data must be prepared to be sent across the media in manageable pieces. Most networks have a limitation on the amount of data that can be included in a single packet. Transport layer protocols have services that segment the application data into blocks of data that are an appropriate size. This service includes the encapsulation required on each piece of data. A header, used for reassembly, is added to each block of data. This header is used to track the data stream. At the destination, the transport layer must be able to reconstruct the pieces of data into a complete data stream that is useful to the application layer.
• Identifying the proper application (ports) for each communication stream. There may be many applications or services running on each host in the network. To pass data streams to the proper applications, the transport layer must identify the target application. To accomplish this, the transport layer assigns each application an identifier. This identifier is called a port number. Each software process that needs to access the network is assigned a port number unique in that host. The transport layer uses ports to identify the application or service.

Any additional properties of the transport layer comes from the protcol being used, most commonly TCP or UDP.