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3. principles/transport
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81 ../../principles/transport.rst:515
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — An important point to note about the connection-oriented service is its reliability. A `connection-oriented` service can only guarantee the correct delivery of all SDUs provided that the connection has been released gracefully. This implies that while the connection is active, there is no guarantee for the actual delivery of the SDUs exchanged as the connection may need to be abruptly released at any time. 409/10000 · 409
82 ../../principles/transport.rst:520
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The request-response service 28/10000 · 28
83 ../../principles/transport.rst:524
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The `request-response service` is a compromise between the `connectionless service` and the `connection-oriented service`. Many applications need to send a small amount of data and receive a small amount of information back. This is similar to procedure calls in programming languages. A call to a procedure takes a few arguments and returns a simple answer. In a network, it is sometimes useful to execute a procedure on a different host and receive the result of the computation. Executing a procedure on another host is often called Remote Procedure Call. It is possible to use the `connectionless service` for this application. However, since this service is usually unreliable, this would force the application to deal with any type of error that could occur. Using the `connection oriented service` is another alternative. This service ensures the reliable delivery of the data, but a connection must be created before the beginning of the data transfer. This overhead can be important for applications that only exchange a small amount of data. 1051/10000 · 1051
84 ../../principles/transport.rst:526
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The `request-response service` allows to efficiently exchange small amounts of information in a request and associate it with the corresponding response. This service can be depicted by using the time-sequence diagram below. 224/10000 · 224
85 ../../principles/transport.rst:545
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Services and layers 19/10000 · 19
86 ../../principles/transport.rst:547
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — In the previous sections, we have described services that are provided by the transport layer. However, it is important to note that the notion of service is more general than in the transport layer. As explained earlier, the network layer also provides a service, which in most networks is an unreliable connectionless service. There are network layers that provide a connection-oriented service. Similarly, the datalink layer also provides services. Some datalink layers will provide a connectionless service. This will be the case in Local Area Networks for examples. Other datalink layers, e.g. in public networks, provide a connection oriented service. 657/10000 · 657
87 ../../principles/transport.rst:554
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The transport layer entity interacts with both a user in the application layer and the network layer. It improves the network layer service to make it usable by applications. From the application's viewpoint, the main limitations of the network layer service come from its unreliable service: 292/10000 · 292
88 ../../principles/transport.rst:556
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the network layer may corrupt data; 35/10000 · 35
89 ../../principles/transport.rst:557
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the network layer may loose data; 33/10000 · 33
90 ../../principles/transport.rst:558
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the network layer may not deliver data in-order; 48/10000 · 48
91 ../../principles/transport.rst:559
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the network layer has an upper bound on maximum length of the data; 67/10000 · 67
92 ../../principles/transport.rst:560
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the network layer may duplicate data. 37/10000 · 37
93 ../../principles/transport.rst:562
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — To deal with these issues, the transport layer includes several mechanisms that depend on the service that it provides. It interacts with both the applications and the underlying network layer. 193/10000 · 193
94 ../../principles/transport.rst:568
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Interactions between the transport layer, its user, and its network layer provider 82/10000 · 82
95 ../../principles/transport.rst:570
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — We have already described in the datalink layers mechanisms to deal with data losses and transmission errors. These techniques are also used in the transport layer. 164/10000 · 164
96 ../../principles/transport.rst:574
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Connectionless transport 24/10000 · 24
97 ../../principles/transport.rst:576
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The simplest service that can be provided in the transport layer is the connectionless transport service. Compared to the connectionless network layer service, this transport service includes two additional features : 217/10000 · 217
98 ../../principles/transport.rst:578
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — an `error detection` mechanism that allows detecting corrupted data 67/10000 · 67
99 ../../principles/transport.rst:579
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — a `multiplexing technique` that enables several applications running on one host to exchange information with another host 122/10000 · 122
100 ../../principles/transport.rst:583
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — To exchange data, the transport protocol encapsulates the SDU produced by its user inside a `segment`. The `segment` is the unit of transfer of information in the transport layer. Transport layer entities always exchange segments. When a transport layer entity creates a segment, this segment is encapsulated by the network layer into a packet which contains the segment as its payload and a network header. The packet is then encapsulated in a frame to be transmitted in the datalink layer. 491/10000 · 491