Changes in cnp3-ebook/principles/transport

None Resource update cnp3-ebook / principles/transport — English	File `locale/pot/principles/transport.pot` was added. a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English The first solution to release a transport connection is to define a new control segment (e.g. the `DR` segment for Disconnection Request) and consider the connection to be released once this segment has been sent or received. This is illustrated in the figure below. English 266 characters edited Current translation Read only The first solution to release a transport connection is to define a new control segment (e.g. the `DR` segment for Disconnection Request) and consider the connection to be released once this segment has been sent or received. This is illustrated in the figure below. a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English Compared to reliable protocols in the datalink layer, reliable transport protocols encode their sequence numbers using more bits. 32 bits and 64 bits sequence numbers are frequent in the transport layer while some datalink layer protocols encode their sequence numbers in an 8 bits field. This large sequence number space is motivated by two reasons. First, since the sequence number is incremented for each transmitted byte, a single segment may consume one or several thousands of sequence numbers. Second, a reliable transport protocol must be able to detect delayed segments. This can only be done if the number of bytes transmitted during the MSL period is smaller than the sequence number space. Otherwise, there is a risk of accepting duplicate segments. English 761 characters edited Current translation Read only Compared to reliable protocols in the datalink layer, reliable transport protocols encode their sequence numbers using more bits. 32 bits and 64 bits sequence numbers are frequent in the transport layer while some datalink layer protocols encode their sequence numbers in an 8 bits field. This large sequence number space is motivated by two reasons. First, since the sequence number is incremented for each transmitted byte, a single segment may consume one or several thousands of sequence numbers. Second, a reliable transport protocol must be able to detect delayed segments. This can only be done if the number of bytes transmitted during the MSL period is smaller than the sequence number space. Otherwise, there is a risk of accepting duplicate segments. a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English Reliable transport protocols also use sequence numbers and acknowledgment numbers. While reliable protocols in the datalink layer use one sequence number per frame, reliable transport protocols consider all the data transmitted as a stream of bytes. In these protocols, the sequence number placed in the segment header corresponds to the position of the first byte of the payload in the bytestream. This sequence number allows detecting losses but also enables the receiver to reorder the out-of-sequence segments. This is illustrated in the figure below. English 555 characters edited Current translation Read only Reliable transport protocols also use sequence numbers and acknowledgment numbers. While reliable protocols in the datalink layer use one sequence number per frame, reliable transport protocols consider all the data transmitted as a stream of bytes. In these protocols, the sequence number placed in the segment header corresponds to the position of the first byte of the payload in the bytestream. This sequence number allows detecting losses but also enables the receiver to reorder the out-of-sequence segments. This is illustrated in the figure below. a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English The first point which is common between the two layers is that both use CRCs or checksums to detect transmission errors. Each segment contains a CRC/checksum which is computed over the entire segment (header and payload) by the sender and inserted in the header. The receiver recomputes the CRC/checksum for each received segment and discards all segments with an invalid CRC. English 376 characters edited Current translation Read only The first point which is common between the two layers is that both use CRCs or checksums to detect transmission errors. Each segment contains a CRC/checksum which is computed over the entire segment (header and payload) by the sender and inserted in the header. The receiver recomputes the CRC/checksum for each received segment and discards all segments with an invalid CRC. a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English The last scenario is less likely, but it is important to consider it as well. The remote entity receives an old `CR` segment. It notes the connection attempt and acknowledges it by sending a `CA` segment. The initiating entity does not have a matching connection attempt and replies by sending a `REJECT`. Unfortunately, this segment never reaches the remote entity. Instead, the remote entity receives a retransmission of an older `CA` segment that contains the same sequence number as the first `CR` segment. This `CA` segment cannot be accepted by the remote entity as a confirmation of the transport connection as its acknowledgment number cannot have the same value as the sequence number of the first `CA` segment. English 720 characters edited Current translation Read only The last scenario is less likely, but it is important to consider it as well. The remote entity receives an old `CR` segment. It notes the connection attempt and acknowledges it by sending a `CA` segment. The initiating entity does not have a matching connection attempt and replies by sending a `REJECT`. Unfortunately, this segment never reaches the remote entity. Instead, the remote entity receives a retransmission of an older `CA` segment that contains the same sequence number as the first `CR` segment. This `CA` segment cannot be accepted by the remote entity as a confirmation of the transport connection as its acknowledgment number cannot have the same value as the sequence number of the first `CA` segment. a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English Unfortunately, this scheme is not sufficient given the unreliable network layer. Since the network layer is imperfect, the `CR` or `CA` segments can be lost, delayed, or suffer from transmission errors. To deal with these problems, the control segments must be protected by a CRC or a checksum to detect transmission errors. Furthermore, since the `CA` segment acknowledges the reception of the `CR` segment, the `CR` segment can be protected using a retransmission timer. English 472 characters edited Current translation Read only Unfortunately, this scheme is not sufficient given the unreliable network layer. Since the network layer is imperfect, the `CR` or `CA` segments can be lost, delayed, or suffer from transmission errors. To deal with these problems, the control segments must be protected by a CRC or a checksum to detect transmission errors. Furthermore, since the `CA` segment acknowledges the reception of the `CR` segment, the `CR` segment can be protected using a retransmission timer. a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English The simplest approach to establish a transport connection would be to define two special control segments : `CR` (Connection Request) and `CA` (Connection Acknowledgment). The `CR` segment is sent by the transport entity that wishes to initiate a connection. If the remote entity wishes to accept the connection, it replies by sending a `CA` segment. The `CR` and `CA` segments contain `port numbers` that allow identifying the communicating applications. The transport connection is considered to be established once the `CA` segment has been received. At that point, data segments can be sent in both directions. English 614 characters edited Current translation Read only The simplest approach to establish a transport connection would be to define two special control segments : `CR` (Connection Request) and `CA` (Connection Acknowledgment). The `CR` segment is sent by the transport entity that wishes to initiate a connection. If the remote entity wishes to accept the connection, it replies by sending a `CA` segment. The `CR` and `CA` segments contain `port numbers` that allow identifying the communicating applications. The transport connection is considered to be established once the `CA` segment has been received. At that point, data segments can be sent in both directions. a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English Like the connectionless service, the connection-oriented service allows several applications running on a given host to exchange data with other hosts. The port numbers described above for the connectionless service are also used by the connection-oriented service to multiplex several applications. Similarly, connection-oriented protocols use checksums/CRCs to detect transmission errors and discard segments containing an invalid checksum/CRC. English 446 characters edited Current translation Read only Like the connectionless service, the connection-oriented service allows several applications running on a given host to exchange data with other hosts. The port numbers described above for the connectionless service are also used by the connection-oriented service to multiplex several applications. Similarly, connection-oriented protocols use checksums/CRCs to detect transmission errors and discard segments containing an invalid checksum/CRC. a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English Compared to the connectionless network layer service, the transport layer service allows several applications running on a host to exchange SDUs with several other applications running on remote hosts. Let us consider two hosts, e.g. a client and a server. The network layer service allows the client to send information to the server, but if an application running on the client wants to contact a particular application running on the server, then an additional addressing mechanism is required. The network layer address identifies a host, but it is not sufficient to differentiate the applications running on a host. `Port numbers` provides this additional addressing. When a server application is launched on a host, it registers a `port number`. This `port number` will be used by the clients to contact the server process. English 829 characters edited Current translation Read only Compared to the connectionless network layer service, the transport layer service allows several applications running on a host to exchange SDUs with several other applications running on remote hosts. Let us consider two hosts, e.g. a client and a server. The network layer service allows the client to send information to the server, but if an application running on the client wants to contact a particular application running on the server, then an additional addressing mechanism is required. The network layer address identifies a host, but it is not sufficient to differentiate the applications running on a host. `Port numbers` provides this additional addressing. When a server application is launched on a host, it registers a `port number`. This `port number` will be used by the clients to contact the server process. a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English an `error detection` mechanism that allows detecting corrupted data English 67 characters edited Current translation Read only an `error detection` mechanism that allows detecting corrupted data a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English the network layer may duplicate data. English 37 characters edited Current translation Read only the network layer may duplicate data. a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English the network layer has an upper bound on maximum length of the data; English 67 characters edited Current translation Read only the network layer has an upper bound on maximum length of the data; a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English the network layer may not deliver data in-order; English 48 characters edited Current translation Read only the network layer may not deliver data in-order; a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English the network layer may loose data; English 33 characters edited Current translation Read only the network layer may loose data; a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English the network layer may corrupt data; English 35 characters edited Current translation Read only the network layer may corrupt data; a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English 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: English 292 characters edited Current translation Read only 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: a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English 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. English 409 characters edited Current translation Read only 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. a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English The third phase of a connection is its release. As a connection involves three parties (two users and one service provider), any of them can request the termination of the connection. Usually, connections are terminated upon request of one user once the data transfer is finished. However, sometimes the service provider may be forced to terminate a connection. This can be due to lack of resources inside the service provider or because one of the users is not reachable anymore through the network. In this case, the service provider will issue `Disconnect.indication` primitives to both users. These primitives will contain, as parameter, some information about the reason for the termination of the connection. Unfortunately, as illustrated in the figure below, when a service provider is forced to terminate a connection it cannot guarantee that all SDUs sent by each user have been delivered to the other user. This connection release is said to be abrupt as it can cause losses of data. English 993 characters edited Current translation Read only The third phase of a connection is its release. As a connection involves three parties (two users and one service provider), any of them can request the termination of the connection. Usually, connections are terminated upon request of one user once the data transfer is finished. However, sometimes the service provider may be forced to terminate a connection. This can be due to lack of resources inside the service provider or because one of the users is not reachable anymore through the network. In this case, the service provider will issue `Disconnect.indication` primitives to both users. These primitives will contain, as parameter, some information about the reason for the termination of the connection. Unfortunately, as illustrated in the figure below, when a service provider is forced to terminate a connection it cannot guarantee that all SDUs sent by each user have been delivered to the other user. This connection release is said to be abrupt as it can cause losses of data. a year ago
None String updated in the repository cnp3-ebook / principles/transport — English	English An invocation of the `connection-oriented service` is divided into three phases. The first phase is the establishment of a `connection`. A `connection` is a temporary association between two users through a service provider. Several connections may exist at the same time between any pair of users. Once established, the connection is used to transfer SDUs. `Connections` usually provide one bidirectional stream supporting the exchange of SDUs between the two users that are associated through the `connection`. This stream is used to transfer data during the second phase of the connection called the `data transfer` phase. The third phase is the termination of the connection. Once the users have finished exchanging SDUs, they request the service provider to terminate the connection. As we will see later, there are also some cases where the service provider may need to terminate a connection itself. English 906 characters edited Current translation Read only An invocation of the `connection-oriented service` is divided into three phases. The first phase is the establishment of a `connection`. A `connection` is a temporary association between two users through a service provider. Several connections may exist at the same time between any pair of users. Once established, the connection is used to transfer SDUs. `Connections` usually provide one bidirectional stream supporting the exchange of SDUs between the two users that are associated through the `connection`. This stream is used to transfer data during the second phase of the connection called the `data transfer` phase. The third phase is the termination of the connection. Once the users have finished exchanging SDUs, they request the service provider to terminate the connection. As we will see later, there are also some cases where the service provider may need to terminate a connection itself. a year ago

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