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... transport entity and the
network service provider through the exchange of network
service primitives.
...
... entity and the
network service provider through the exchange of network
service primitives.
These procedures are defined in the main text of the standard
...
... DP 8348 Information processing systems - Open systems
interconnection - Connection-oriented network service
definition.
...
... transport service.
3.2.3 network service provider:
An abstract machine that models the totality of the entities
...
...
An abstract machine that models the totality of the entities
providing the network service, as viewed by a transport entity.
...
... entities.
3.2.28 owner (of a network connection):
The transport ...
... entity that issued the N-CONNECT request leading to
the creation of that network connection.
3.2.29 retained TPDU:
...
...
The protocol specified in this International Standard assumes the
use of the network service defined in DP 8348.
...
... | | | Reason. | Z |
+---------------------------------------------------------------+
Table 2. Network service primitives
...
... X - The Transport Protocol assumes that this facility is
provided in all networks.
Y - The Transport Protocol ...
... Y - The Transport Protocol assumes that this facility is
provided in some networks and a mechanism is provided to
optionally use the facility.
...
...
1 - The parameters listed in this table are those in the
current network service (first DP 8348).
...
... bridge the gap between the services available from the Network
Layer and those to be offered to the TS ...
... d) blocking;
e) temporary release of network connections;
f) alternative checksum algorithm ...
... multiplexing and demultiplexing (see 6.15), a function
used to share a single network connection between two or
more transport connections;
...
... b) decide whether to multiplex multiple transport connections
onto a single network connection (see 6.5);
c) establish the optimum TPDU size (see 6.5);
...
...
c) splitting and recombining (see 6.23), a function allowing
the simultaneous use of two or more network connections to
support the same transport connection;
...
... Transport connections of classes 2, 3 and 4 may be
multiplexed together onto the same network connection.
5.4.2 Negotiation ...
... primitives;
b) the quality of the available network services;
c) the user required service ...
... network connection
The following list classifies network services in terms of
quality with respect to error behavior in relation to user
requirements ...
...
a) Type A. Network connection with acceptable residual error
rate (for example not signalled by disconnect or reset)
and acceptable rate of signalled errors.
...
... and acceptable rate of signalled errors.
b) Type B. Network connections with acceptable residual
error rate (for example not signalled by disconnect or
reset) but unacceptable rate of signalled errors.
...
... reset) but unacceptable rate of signalled errors.
c) Type C. Network connections with unacceptable residual
error rate.
...
... transport entity is aware of the quality
of service provided by particular network connections.
5.4.4 Characteristics of Class ...
...
Class 0 has been designed to be used with type A network
connections.
5.4.5 Characteristics of Class ...
... Class 2 provides a way to multiplex several transport connections
onto a single network connection. This class has been designed
to be used with type A network connections ...
... network connection. This class has been designed
to be used with type A network connections.
5.4.6.2 Use of explicit flow ...
... transport-connection-end-points and on the network connection.
Typical use is when traffic is heavy and continuous, or when
...
... terminals, and when no multiplexing onto
network connections is required. Expedited data is never
available.
...
... Class 3 provides the characteristics of Class 2 plus the ability
to recover from network disconnect or reset. Selection of this
class is usually based upon reliability ...
... class also provides for increased throughput capability and
additional resilience against network failure. Class 4 has been
designed to be used with type C network connections ...
... network failure. Class 4 has been
designed to be used with type C network connections.
5.5 Model of the transport layer ...
... protocol exchanges are effected using the
services of the Network Layer as defined by the Network Service
...
... services of the Network Layer as defined by the Network Service
Definition DP 8348 through one or more NSAPs ...
... in this clause.
NOTE - Where network service primitives and TPDUs and parameters
used are not significant for a particular element of procedure,
...
... they have not been included in the specification.
6.1 Assignment to network connection
6.1.1 Purpose
...
... The procedure is used in all classes to assign transport
connections to network connections.
6.1.2 Network service ...
... network connections.
6.1.2 Network service primitives
The procedure makes use of the following network service ...
... Network service primitives
The procedure makes use of the following network service
primitives:
...
...
Each transport connection shall be assigned to a network
connection. The initiator may assign the transport connection to
...
... initiator may assign the transport connection to
an existing network connection of which it is the owner or to a
new network connection (see Note 1) which it creates ...
... an existing network connection of which it is the owner or to a
new network connection (see Note 1) which it creates for this
purpose.
...
... The initiator shall not assign or reassign the transport
connection to an existing network connection if the protocol
class(es) proposed or the class in use for the transport
connection ...
... protocol
class(es) proposed or the class in use for the transport
connection are incompatible with the current usage of the network
connection with respect to multiplexing (see Note 2).
...
... entity may reassign a
transport connection to another network connection joining the
same NSAPs, provided that it is the owner of the network
connection ...
... network connection joining the
same NSAPs, provided that it is the owner of the network
connection and that the transport connection is assigned to only
one network connection ...
... network
connection and that the transport connection is assigned to only
one network connection at any given time.
During the splitting procedure (see 6.23), a transport ...
... entity may
assign a transport connection to any additional network
connection joining the same NSAPs, provided that it is the owner
of the network connection ...
... network
connection joining the same NSAPs, provided that it is the owner
of the network connection and that multiplexing is possible on
the network connection ...
... network connection and that multiplexing is possible on
the network connection.
The responder ...
... NOTES
1. When a new network connection is created, the quality of
service requested is a local matter, although it will
...
... transport
connection(s) expected to be assigned to it.
2. An existing network connection may also not be suitable
if, for example, the quality of service requested for the
...
... transport connection cannot be attained by using or
enhancing the network connection.
3. A network connection ...
... network connection.
3. A network connection with no transport connection(s)
assigned to it, may be available after initial
...
... transport connections
previously assigned to it have been released. It is
recommended that only the owner of such a network
connection should release it. Furthermore, it is
recommended that it not be released immediately after the
transmission of the final TPDU of a transport connection ...
... transport connection concerned.
4. After the failure of a network connection, transport
connections which were previously multiplexed together may
be assigned to different network connections ...
... network connection, transport
connections which were previously multiplexed together may
be assigned to different network connections, and vice
versa.
...
...
6.2.2 Network Service Primitives
The procedure uses the following network service ...
... Network Service Primitives
The procedure uses the following network service primitives:
a) N-DATA ...
... protocol are listed in 4.2.
When the network expedited variant has been selected for class 1,
the transport ...
...
6.5.2 Network service primitives
The procedure uses the following network service ...
... Network service primitives
The procedure uses the following network service primitive:
N-DATA ...
... - checksum;
- additional option selection (i.e. use of network
expedited in class 1, use of receipt confirmation in
...
... transport
connection being created to one (or more if the splitting
procedure is being use) network connection(s). It is this set of
network connections over which the TPDUs are sent. During this
...
... procedure is being use) network connection(s). It is this set of
network connections over which the TPDUs are sent. During this
exchange, all information and parameters needed for the transport
...
...
reset or disconnect the network connection and, in classes 1
and 3 freeze the reference (see 6.18). For all other
...
... and 3 freeze the reference (see 6.18). For all other
transport connection(s) multiplexed on the same network
connection the procedures for reset or disconnect as
appropriate should be followed.
...
... (see 6.13).
When the network expedited variant of the expedited data transfer
(see 6.11) has been agreed (possible in class ...
... This mechanism is symmetrical and provides identification
of the transport connection independent of the network
connection. The range of references used for transport
connections, in a given transport ...
... transport service access points. When either network
address unambiguously defines the transport address ...
...
q) the use of network receipt confirmation and network
expedited when class 1 is to be used.
...
... Class 1 only) | No | No |
|-----------------------|------------------|------------------|
|Use of the network | Yes | Yes or No |
|expedited variant | No | No |
|(Class ...
... transport connection is directly correlated
with the lifetime of the network connection.
2. The use of the explicit variant of the release procedure
...
... enables the transport connection to be released independently
of the underlying network connection.
6.7.2 Network service ...
... network connection.
6.7.2 Network service primitives
The procedure makes use of the following network service ...
... Network service primitives
The procedure makes use of the following network service
primitives:
...
... entity disconnects a
transport connection by disconnecting the network connection to
which it is assigned. When a transport entity ...
...
3) After the release of a transport connection the network
connection can be released or retained to enable its re-
use for the assignment of other transport connections (see
...
... DR TPDU
within time TS2, it should either reset or disconnect the
network connection, and freeze the reference when
appropriate (see 6.18). For all other transport
connection(s) multiplexed on this network connection ...
... network connection, and freeze the reference when
appropriate (see 6.18). For all other transport
connection(s) multiplexed on this network connection the
procedures for reset or disconnect as appropriate should
be followed.
...
... CC TPDU before
sending a DR TPDU and the network connection is reset or
released, it should consider the transport connection
...
... indication.
6.8.2 Network service primitives
The procedure makes use of the following service ...
... 6.8.3 Procedure
When, on the network connection to which a transport connection
is assigned, an N-DISCONNECT ...
...
6.9.2 Network service primitives
This procedure makes use of the following network service ...
... Network service primitives
This procedure makes use of the following network service
primitives:
...
... 2) if the NSDU cannot be decoded issue an N-RESET or N-
DISCONNECT request for the network connection and for
all the transport connections assigned to this network
connection ...
... network connection and for
all the transport connections assigned to this network
connection (if any), apply the procedures defined for
handling of network signalled reset or disconnect.
...
... transport connections assigned to this network
connection (if any), apply the procedures defined for
handling of network signalled reset or disconnect.
If the NSDU can be decoded and is not corrupted, the
...
... entity shall:
c) if the network connection on which the NSDU was received
has a class 0 transport connection ...
... CR TPDU then, if it is a duplicate, as
recognized by using the NSAPs of the network connection, and the
SRC-REF parameter, then it is associated with the transport
connection created ...
... transport connection.
If the received TPDU is a DT TPDU and the network connection has
a class 0 or 1 transport connection ...
... the transport entity shall respond on the same network
connection with a DR TPDU if the TPDU is a CC TPDU, with a
...
... DST-REF is allocated to a connection, but the TPDU
is received on a network connection to which the
connection has not been assigned then there are three
...
... transport connection is of class 4 and if the
TPDU is received on a network connection with the same
pair of NSAPs as that of the CR ...
... 2) if the transport connection is not assigned to any
network connection (waiting for reassignment after
failure) and if the TPDU is received on a network
connection with the same pair of NSAPs ...
... network connection (waiting for reassignment after
failure) and if the TPDU is received on a network
connection with the same pair of NSAPs as that of the
CR ...
... Expedited data transfer procedures are selected during connection
establishment. The network normal data variant may be used in
classes 1, 2, 3 and 4. The network ...
... network normal data variant may be used in
classes 1, 2, 3 and 4. The network expedited variant is only
used in class 1.
...
... class 1.
6.11.2 Network service primitives
The procedure makes use of the following network service ...
... Network service primitives
The procedure makes use of the following network service
primitives:
...
... NOTES
1. The network normal data variant is used, except when the
network expedited variant (available in Class ...
... 1. The network normal data variant is used, except when the
network expedited variant (available in Class 1 only), has
been agreed, in which case ED and EA TPDUs are conveyed in
...
... 6.2.3).
2. No TPDUs can be transmitted using network expedited until
the CC TPDU becomes acknowledged, to prevent the network ...
... network expedited until
the CC TPDU becomes acknowledged, to prevent the network
expedited from overtaking the CC TPDU.
...
... provider signalled disconnect.
6.12.2 Network service primitives
The procedure uses the following network service ...
... Network service primitives
The procedure uses the following network service primitive:
N-DISCONNECT ...
...
When an N-DISCONNECT indication is received from the network
connection to which a transport connection is assigned, the
initiator ...
...
1) assign the transport connection to a different network
connection (see 6.1) and start its TTR timer if not
...
... initiator. Its value shall not
exceed two minutes minus the sum of the maximum disconnect
propagation delay and the transit delay of the network
connections (see note 1). The value for the TTR timer may be
indicated in the CR ...
... greater than the sum of the TTR timer plus the maximum disconnect
propagation delay plus the transit delay of the network
connections.
If the reassignment time parameter is not present in the CR ...
...
NOTE - Use of confirmation of receipt variant depends on the
availability of the network layer receipt confirmation service
...
... and the expected cost reduction.
6.13.2 Network service primitives
The procedure uses the following network service ...
... Network service primitives
The procedure uses the following network service primitives:
a) N-DATA ...
...
2. Use of the confirmation request parameter may affect the
quality of network service.
...
... during reassignment after failure according to 6.12.
6.14.2 Network service primitives
The procedure makes use of the following network service ...
... Network service primitives
The procedure makes use of the following network service
primitive:
...
... 1. A repeated CR TPDU can be identified by being on a
network connection with the appropriate network
addresses ...
... CR TPDU can be identified by being on a
network connection with the appropriate network
addresses and having a correct source reference.
...
... 2. The transport entity should not use network expedited
until the CC TPDU is acknowledged (see 6.5). This
...
... until the CC TPDU is acknowledged (see 6.5). This
rule prevents the network expedited from overtaking
the CC TPDU.
...
... Classes 2, 3 and 4 to allow several transport connections to
share a network connection at the same time.
6.15.2 TPDUs and parameters used
...
... The transport entities shall be able to send and receive on the
same network connection TPDUs belonging to different transport
connections.
...
... NOTE - Although a checksum algorithm has to be adapted to the
type of errors expected on the network connection, at present
only one algorithm is defined.
...
... transport connection the TPDU is
related; further action may be taken for all the transport
connections assigned to the network connection (see 6.9).
3. The checksum ...
... The resequencing procedure is used in Class 4 to cope with
misordering of TPDUs by the network service provider.
6.20.2 TPDUs and parameters used
...
... The inactivity control procedure is used in Class 4 to cope with
unsignalled termination of a network connection.
...
... actions so as not to jeopardize any other transport connections
not assigned to that network connection:
a) ignoring the TPDU;
...
...
c) resetting or closing the network connection; or
d) invoking the release procedures appropriate to the class ...
... This procedure is used only in class 4 to allow a transport
connection to make use of multiple network connections to provide
additional resilience against network ...
... multiple network connections to provide
additional resilience against network failure, to increase
throughput, or for other reasons.
...
... When this procedure is being used, a transport connection may be
assigned (see 6.1) to multiple network connections (see note 1).
TPDUs for the connection ...
... connections (see note 1).
TPDUs for the connection may be sent over any such network
connection.
If the use of Class ...
... entity following the negotiation rules, then no network
connection except that over which the CR TPDU was sent may have
this transport connection ...
... entity may assign the connection to
further network connections of which it is the owner at
any time during the life of the transport connection.
...
...
3. In order to enable the detection of unsignalled network
connection failures, a transport entity performing
...
... entity performing
splitting should ensure that TPDUs are sent at intervals
on each supporting network connection, for example, by
sending successive TPDUs on successive network
connections, where the set of network connections ...
... on each supporting network connection, for example, by
sending successive TPDUs on successive network
connections, where the set of network connections is used
cyclically. By monitoring each network connection ...
... network connection, for example, by
sending successive TPDUs on successive network
connections, where the set of network connections is used
cyclically. By monitoring each network connection, a
...
... network
connections, where the set of network connections is used
cyclically. By monitoring each network connection, a
transport entity ...
... transport entity may detect unsignalled network connection
failures, following the inactivity procedures defined in
12.2.3.3. Thus, for each network connection ...
... network connection
failures, following the inactivity procedures defined in
12.2.3.3. Thus, for each network connection no period I
(see 12.2.3.1) may elapse without the receipt of some TPDU
for some transport connection ...
... | ao|Negotiable procedure whose implementation in equipment is|
| |optional and where use depends on availability within the|
| |network service |
|---|---------------------------------------------------------|
|(1)|Not applicable in class ...
... | |rence | | | | | | |
|-----------------------------|------|------------|--|--|--|--|--|
| Assignment to network Conn. | 6.1 | | *| *| *| *| *|
|-----------------------------|------|------------|--|--|--|--|--|
| TPDU Transfer | 6.2 | | *| *| *| *| *|
...
... |-----------------------------|------|------------|--|--|--|--|--|
| Expedited Data Transfer | 6.11 | network | | | *| | |
| | | normal | | m|(1) *| *|
| | | network ...
... network | | | *| | |
| | | normal | | m|(1) *| *|
| | | network | | | | | |
| | | expedited | |ao| | | |
|-----------------------------|------|------------|--|--|--|--|--|
...
... transport connections with flow control based on
the network service provided flow control, and disconnection
based on the network service ...
... network service provided flow control, and disconnection
based on the network service disconnection.
8.2 Procedures for class ...
... transport entities shall use the following procedures:
a) assignment to network connection (see 6.1); then
b) connection establishment ...
... transport connections with flow control based on
the network service provided flow control, error recovery,
...
... data transfer, disconnection, and also the ability to
support consecutive transport connections on a network
connection.
This class ...
... class provides the functionality of Class 0 plus the ability
to recover after a failure signalled by the Network Service,
without involving the TS-user.
...
... class and its use depends on the availability of the
network layer receipt confirmation service, and the
...
... transport entities shall use the following procedures:
a) assignment to network connection (see 6.1); then
b) connection establishment ...
...
The transport entities shall use either the network normal data
or the network expedited variants of the expedited data transfer ...
... transport entities shall use either the network normal data
or the network expedited variants of the expedited data transfer
procedure (see 6.11) if their use has been selected during
...
... been designed such that if the initiator proposes the use
of the network normal data variant (i.e. the mandatory
...
... this option and if the initiator proposes use of the
network expedited variant, the responder is entitled to
select use of the network ...
... network expedited variant, the responder is entitled to
select use of the network normal data variant.
2. This numbering enables the receiving ...
... error recovery is provided.
If the network connection resets or disconnects, the transport
connection is terminated without the transport release procedure
...
... transport entities shall use the following procedures:
a) assignment to network connection (see 6.1); then
b) connection establishment ...
...
The transport entities shall follow the network normal variant of
the expedited data transfer procedure in 6.11 if its use has been
...
... explicit flow control) plus the ability to recover after a
failure signalled by the Network Layer without involving the user
of the transport service ...
... transport entities shall use the following procedures;
a) assignment to network connections (see 6.1); then
b) connection establishment ...
...
The transport entities shall follow the network normal data
variant of expedited data transfer procedure in 6.11 if its use
...
... Further on this class provides additional resilience against
network failure and increased throughput capability by allowing a
transport connection ...
... throughput capability by allowing a
transport connection to make use of multiple network connections.
...
... | | | a TPDU by the local transport en- |
| | | tity from the network layer and |
| | | the transmission of the corres- |
...
... | | | for protection against unsignalled |
| | | breaks in the network connection. |
| | | |
| W |Window time | A bound for the maximum time a |
...
... lifetime (MLR, MRL)
The network layer is assumed to provide, as an aspect of its
grade of service ...
... service, for a bound on the maximum lifetime of NSDUs in
the network. This value may be different in each direction of
transfer through a network between two transport ...
... the network. This value may be different in each direction of
transfer through a network between two transport entities. The
values, for both directions of transfer, are assumed to be Known
...
... transport entity to the
network and receipt of any copy of the NSDU from the network at
the remote transport ...
... entity to the
network and receipt of any copy of the NSDU from the network at
the remote transport entity ...
... transport entity to the
network and receipt of any copy of the NSDU from the network at
the local transport ...
... entity to the
network and receipt of any copy of the NSDU from the network at
the local transport entity ...
... 12.2.1.1.2 Expected maximum transit delay (ELR, ERL)
The network layer is assumed to provide, as an aspect of its
grade of service ...
... grade of service, an expected maximum transit delay for NSDUs in
the network. This value may be different in each direction of
transfer through a network between two transport ...
... the network. This value may be different in each direction of
transfer through a network between two transport entities. The
values, for both directions of transfer, are assumed to be Known
...
... transport entities. The expected maximum transit delay
local-to-remote (ELR) is the maximum delay suffered by all but a
small proportion of NSDUs transferred through the network from
the local transport entity ...
... expected maximum transit delay remote-to-local (ERL) is the
maximum delay suffered by all but a small proportion of NSDUs
transfer through the network from the remove transport entity ...
... entity is assumed to provide a bound for the
maximum time which can elapse between its receipt of a TPDU from
the Network Layer and its transmission of the corresponding
response. This value is referred to as AL. The corresponding
...
... transport entities shall use the following procedures:
a) assignment to network connection (see 6.1);
b) connection establishment ...
... a) Inactivity Time (I)
To protect against unsignalled breaks in the network
connection or failure of the peer transport entity (half-open
...
... the expiration of the inactivity timer will fail, as such
expiration indicates probable failure of the supporting network
connection or of the remote transport entity.
...
...
The transport entities shall follow the network normal data
variant of the expedited data transfer procedures (see 6.11), if
...
... BIT| OPTION |
|---|--------------------------------------------------|
| 4 | 1= Use of network expedited in Class 1 |
| | 0= Non use of network ...
... 8) 128 + 7 - Reference overflow
9) 128 + 8 - Connection request refused on this network
connection
10) 128 + 9 - Not used
11) 128 + 10- Header ...
... flow control" option is selected, and for Class 1 when
the network receipt confirmation option is selected.
13.9.1 Structure
...
... TPDUs or both;
b) responding to any other TPDU and operating network service
in accordance with the procedures for the class;
...
... | | | |
|--------------------------|----------------|----------------|
|Use of network expedited | | |
|in Class 1 | NA ...
... | | | | |
|--------------------------|----------|----------|-----------|
|Use of network expedited | | | |
|in Class 1 |NA ...