1 - 2 - 3 - 4 - 6 - 8 - A - B - C - D - E - F - G - H - I - L - M - N - O - P - Q - R - S - T - U - V
transport connection
Click on the red underlined text to get to the source
... entity with whom an initiator wishes to establish a
transport connection.
NOTE - Initiator and responder ...
... NOTE - Initiator and responder are defined with respect to a
single transport connection. A transport entity can be both an
...
... initiator indicates in a CR TPDU as
its first choice for use over the transport connection.
3.2.10 alternative class ...
... initiator indicates in a CR TPDU as an
alternative choice for use over the transport connection.
3.2.11 proposed class ...
... responder indicates in a CC TPDU that
it has chosen for use over the transport connection.
3.2.13 proposed parameter:
...
... initiator indicates in a CR
TPDU that it wishes to use over the transport connection.
3.2.14 selected parameter:
...
... responder indicates in a CC
TPDU that it has chosen for use over the transport connection.
3.2.15 error indication ...
... has been authorized by its peer entity to send at a given time on
a given transport connection.
3.2.20 lower window edge ...
...
A reference that is neither currently in use for identifying a
transport connection or which is in a frozen state.
...
...
These functions are grouped below into those used at all times
during a transport connection and those concerned with connection
establishment, data transfer and release.
...
... The following functions, depending upon the selected class and
options, are used at all times during a transport connection:
a) transmission of TPDUs (see 6.2 and 6.9);
...
... used to share a single network connection between two or
more transport connections;
c) error detection (see 6.10, 6.13 and 6.17), a function used
...
... The purpose of connection establishment is to establish a
transport connection between two TS-users. The following
functions of the transport layer ...
... services (see 6.5);
b) decide whether to multiplex multiple transport connections
onto a single network connection (see 6.5);
...
...
f) provide a means to distinguish between two different
transport connections (see 6.5);
g) transport ...
... data transfer is to permit duplex transmission of
TSDUs between the two TS-users connected by the transport
connection. This purpose is achieved by means of two-way
simultaneous communication and by the following functions, some
of which are used or not used in accordance with the result of
...
... the simultaneous use of two or more network connections to
support the same transport connection;
d) flow ...
... flow of TPDUs between two transport entities on one
transport connection;
e) transport connection ...
... transport connection;
e) transport connection identification, a means to uniquely
identify a transport connection between the pair of
...
... e) transport connection identification, a means to uniquely
identify a transport connection between the pair of
transport entities supporting the connection ...
... connection during the
lifetime of the transport connection;
f) expedited data (see 6.11), a function used to bypass ...
...
The purpose of release (see 6.7 and 6.8) is to provide
disconnection of the transport connection, regardless of the
current activity.
...
... Class.
NOTE - Transport connections of classes 2, 3 and 4 may be
multiplexed together onto the same network connection ...
...
Class 0 provides the simplest type of transport connection and is
fully compatible with the CCITT recommendation S.70 for teletex
terminals ...
...
Class 2 provides a way to multiplex several transport connections
onto a single network connection. This class ...
... flow control
The objective is to provide a basic transport connection with
minimal overheads suitable when explicit disconnection of the
...
... minimal overheads suitable when explicit disconnection of the
transport connection is desirable. The option would typically be
used for unsophisticated terminals, and when no multiplexing ...
... data unit exchanges
between the peer transport entities supporting a transport
connection. These protocol exchanges are effected using the
services ...
... NSAPs.
Transport connection endpoints are identified in end systems by
an internal, implementation dependent, mechanism so that the TS ...
...
The procedure is used in all classes to assign transport
connections to network connections.
...
... 6.1.3 Procedure
Each transport connection shall be assigned to a network
connection. The initiator may assign the transport connection ...
... transport connection shall be assigned to a network
connection. The initiator may assign the transport connection to
an existing network connection of which it is the owner or to a
...
...
The initiator shall not assign or reassign the transport
connection to an existing network connection if the protocol
class(es) proposed or the class ...
... network connection if the 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).
...
... transport entity may reassign a
transport connection to another network connection joining the
same NSAPs ...
... same NSAPs, provided that it is the owner of the network
connection and that the transport connection is assigned to only
one network connection at any given time.
...
... transport entity may
assign a transport connection to any additional network
connection joining the same NSAPs, provided that it is the owner
...
... quality of
service requested is a local matter, although it will
normally be related to the requirements of transport
connection(s) expected to be assigned to it.
2. An existing network connection ...
... 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 with no transport connection(s)
assigned to it, may be available after initial
establishment, or because all of the transport connections ...
... transport connection(s)
assigned to it, may be available after initial
establishment, or because all of the transport connections
previously assigned to it have been released. It is
recommended that only the owner of such a network
connection ...
... 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 -
either a DR TPDU in response to CR ...
... entity
allowing the freeing of any resources associated with the
transport connection concerned.
4. After the failure of a network connection ...
...
4. After the failure of a network connection, transport
connections which were previously multiplexed together may
be assigned to different network connections, and vice
...
... entity shall map a TSDU on to an ordered sequence of
one or more DT TPDUs. This sequence shall not be interrupted by
other DT TPDUs on the same transport connection.
All DT TPDUs except the last DT TPDU in a sequence greater than
...
... transport entity may concatenate TPDUs from the same or
different transport connections.
The set of concatenated TPDUs may contain:
...
... ER, DC TPDUs, provided that these TPDUs come from
different transport connections;
b) no more than one TPDU from the following list: CR ...
...
3. The number of concatenated TPDUs referred to in 6.4.2.a is
bounded by the maximum number of transport connections
which are multiplexed together except during assignment or
reassignment.
...
... Before sending the CR TPDU, the initiator assigns the transport
connection being created to one (or more if the splitting
procedure is being use) network connection ...
... classes 1
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.
...
...
This mechanism is symmetrical and provides identification
of the transport connection independent of the network
connection. The range of references used for transport
connections ...
... transport connection independent of the network
connection. The range of references used for transport
connections, in a given transport entity, is a local
...
... 14, the responder has to accept use of this option over the
transport connection except for the use of the transport
expedited data transfer ...
... option, the responder is entitled to select use of the mandatory
implementation option for use over the transport connection.
6.6 Connection ...
... 6.6.3 Procedure
If a transport connection cannot be accepted, the responder shall
respond to the CR ...
... transport entity in order to
terminate a transport connection. The implicit variant is used
only in class 0. The explicit variant is used in classes ...
... class 0), the
lifetime of the 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.
...
... transport entity disconnects a
transport connection by disconnecting the network connection to
which it is assigned. When a transport ...
... entity receives an N-
DISCONNECT this should be considered as the release of the
transport connection.
6.7.5 Procedure for explicit variant
...
... 6.7.5 Procedure for explicit variant
When the release of a transport connection is to be initiated a
transport entity ...
... DR or DC TPDU it shall consider the
transport connection released;
b) in other cases it shall:
...
...
c) if it has previously sent a DR TPDU for the same transport
connection, consider the transport connection released;
...
... c) if it has previously sent a DR TPDU for the same transport
connection, consider the transport connection released;
d) if it has previously sent a CR ...
...
e) in other cases, send a DC TPDU and consider the transport
connection released.
NOTES
...
... transport entity is
aware of the remote reference for the transport
connection.
2) When the transport connection ...
... transport
connection.
2) When the transport connection is considered as released
the local reference is either available for re-use or is
frozen (see 6.18).
...
... frozen (see 6.18).
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 ...
... transport connection the network
connection can be released or retained to enable its re-
use for the assignment of other transport connections (see
6.1.).
...
... 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
...
... DR TPDU and the network connection is reset or
released, it should consider the transport connection
released and, in classes other than classes ...
... This procedure is used only in classes 0 and 2 to release a
transport connection on the receipt of an N-DISCONNECT or N-RESET
...
...
When, on the network connection to which a transport connection
is assigned, an N-DISCONNECT or N-RESET ...
... N-RESET indication is received,
both transport entities shall consider that the transport
connection is released and so inform the TS-users.
...
...
6.9 Association of TPDUs with transport connections
6.9.1 Purpose
...
... classes to interpret a received
NSDU as TPDU(s) and, if possible, to associate each such TPDU
with a transport connection.
...
... has a class 0 or class 1 transport connection assigned to
it, then treat as a protocol error (see 6.22) for that
...
... it, then treat as a protocol error (see 6.22) for that
transport connection;
b) otherwise
...
... DISCONNECT request for the network connection and for
all the transport connections assigned to this network
connection (if any), apply the procedures defined for
handling of network ...
... network connection on which the NSDU was received
has a class 0 transport connection assigned to it, then
consider the NSDU as forming TPDU and associate the TPDU
with the transport connection ...
... transport connection assigned to it, then
consider the NSDU as forming TPDU and associate the TPDU
with the transport connection (see 6.9.4.2).
d) otherwise, invoke the separation procedures and for each
...
... NSAPs of the network connection, and the
SRC-REF parameter, then it is associated with the transport
connection created by the original value of the CR TPDU;
...
... CR TPDU;
otherwise it is processed as requesting the creation of a new
transport connection.
If the received TPDU is a DT TPDU and the network connection ...
...
where a class 1 transport connection is assigned, then the TPDU
is associated with the transport connection.
...
... class 1 transport connection is assigned, then the TPDU
is associated with the transport connection.
Otherwise, the DST ...
... Otherwise, the DST-REF parameter of the TPDU is used to identify
the transport connection. The following cases are distinguished:
a) if the DST ...
... cases:
1) if the transport connection is of class 4 and if the
TPDU is received on a network connection ...
... considered as performing assignment,
2) if the transport connection is not assigned to any
network connection (waiting for reassignment after
...
... CR TPDU then the association with that transport
connection is made.
3) Otherwise, the TPDU is considered as having a DST ...
... 3) Otherwise, the TPDU is considered as having a DST-REF
not allocated to a transport connection (case a).
c) If the TPDU is a DC ...
... c) If the TPDU is a DC TPDU then it is associated with the
transport connection to which the DST-REF is allocated,
unless the SRC-REF is not the expected one, in which case
...
... CR TPDU is unacknowledged then the DR TPDU is
associated with the transport connection, regardless
of the value of its SRC-REF parameter;
...
... 3) otherwise, the DR TPDU is associated with the
transport connection identified by the DST-REF
parameter.
...
...
f) if none of the above cases apply then the TPDU is
associated with the transport connection identified by the
DST-REF parameter.
...
... sequence number zero to the
TPDU-NR of the first DT TPDU which it transmits for a transport
connection. For subsequent DT TPDUs sent on the same transport
connection, the transport entity ...
... TPDU-NR of the first DT TPDU which it transmits for a transport
connection. For subsequent DT TPDUs sent on the same transport
connection, the transport entity shall allocate a sequence number ...
...
No more than one ED TPDU shall remain unacknowledged at any time
for each direction of a transport connection.
An ED TPDU with a zero length data field ...
... When an N-DISCONNECT indication is received from the network
connection to which a transport connection is assigned, the
initiator shall apply one of the following alternatives:
...
...
1) assign the transport connection to a different network
connection (see 6.1) and start its TTR timer ...
...
b) if the TTR timer has run out, consider the transport
connection as released and freeze the reference (see
6.18).
...
... start its TWR timer if not already started.
The arrival of the first TPDU related to the transport connection
(because of resynchronization by the initiator) completes the
...
...
transport connection is considered released and the reference is
frozen (see 6.18).
...
... After each TPDU is acknowledged, as shown in table 5, the copy
need not be retained. Copies may also be discarded when the
transport connection is released.
...
... The resynchronization procedures are used in Classes 1 and 3 to
restore the transport connection to normal after a reset or
during reassignment after failure according to 6.12.
...
... timer has been previously started and has run
out (i.e. no valid TPDU has been received), the transport
connection is considered as released and the reference is
frozen (see 6.18).
...
... CR or DR or
RJ TPDU) the transport connection is considered as released and
the reference is released (see 6.18).
...
... demultiplexing procedures are used in
Classes 2, 3 and 4 to allow several transport connections to
share a network connection at the same time.
...
... transport entities shall be able to send and receive on the
same network connection TPDUs belonging to different transport
connections.
NOTES
...
...
1. When performing demultiplexing the transport connection to
which the TPDUs apply is determined by the procedures
defined in 6.9.
...
... Multiplexing allows the concatenation of TPDUs belonging
to different transport connections to be transferred in
the same N-DATA primitive (see 6.4).
...
... A transport entity which receives a TPDU for a transport
connection for which the use of checksum has been agreed and
which does not satisfy the above formulas shall discard the TPDU
...
... 2. If the checksum is incorrect, it is not possible to know
with certainty to which transport connection the TPDU is
related; further action may be taken for all the transport
connections assigned to the network connection ...
... with certainty to which transport connection the TPDU is
related; further action may be taken for all the transport
connections assigned to the network connection (see 6.9).
...
... transport entity that receives a TPDU that can be associated to
a transport connection and is invalid or constitutes a protocol
error (see 3.2.16 and 3.2.17) shall take one of the following
actions so as not to jeopardize any other transport connections ...
... transport connection and is invalid or constitutes a protocol
error (see 3.2.16 and 3.2.17) shall take one of the following
actions so as not to jeopardize any other transport connections
not assigned to that network connection:
...
... was detected (see notes 3, 4 and 5).
If the TPDU cannot be associated to a particular transport
connection then see 6.9.
NOTES
...
...
This procedure is used only in class 4 to allow a transport
connection to make use of multiple network connections to provide
...
... 6.23.2 Procedure
When this procedure is being used, a transport connection may be
assigned (see 6.1) to multiple network connections ...
... network
connection except that over which the CR TPDU was sent may have
this transport connection assigned to it.
NOTES
...
... further network connections of which it is the owner at
any time during the life of the transport connection.
...
... network connection no period I
(see 12.2.3.1) may elapse without the receipt of some TPDU
for some transport connection.
...
... | Association of TPDUs with | | | | | | | |
| Transport Connection | 6.9 | | *| *| *| *| *|
|-----------------------------|------|------------|--|--|--|--|--|
| DT TPDU Numbering | 6.10 | normal | | *|m(1)m| m|
...
...
b) association of TPDUs with transport connections (see 6.9);
c) treatment of protocol errors ...
...
NOTE - the lifetime of the transport connection is directly
correlated with the lifetime of the network connection ...
... expedited data transfer, disconnection, and also the ability to
support consecutive transport connections on a network
connection.
...
...
b) association of TPDU with transport connections (see 6.9);
c) treatment of protocol errors ...
... negotiation of the variant of retention until
acknowledgement of TPDUs procedure to be used over the
transport connection has been designed such that if the
initiator proposes the use of the AK variant (i.e. the
...
... negotiation of the variant of expedited data transfer
procedure to be used over the transport connection has
been designed such that if the initiator proposes the use
...
...
Class 2 provides transport connections with or without individual
flow control; no error detection or error recovery ...
...
If the network connection resets or disconnects, the transport
connection is terminated without the transport release procedure
and the TS ...
...
a) association of TPDUs with transport connection (see 6.9);
b) TPDU transfer (see 6.2);
...
... entity constrains the
throughput attainable on the transport connection.
10.2.4.3 Expedited data
...
...
a) association of TPDUs with transport connections (see 6.9);
b) TPDU transfer (see 6.2) and retention until
...
... network failure and increased throughput capability by allowing a
transport connection to make use of multiple network connections.
...
... | | | does not receive a TPDU, initiate |
| | | the release procedure to terminate |
| | | the transport connection. |
| | | |
| | | NOTE - This parameter is required |
...
...
b) association of TPDUs with transport connections (see 6.9);
...
... TPDUs; or
b) one interval is associated with each transport
connection:
1) if the transport ...
... retransmission timer T1 is
maintained on a per TPDU or on a per transport connection
basis, throughput considerations have to be taken into
...
...
transport connection. For subsequent ED TPDU sent on the same
transport connection, the transport ...
... transport connection. For subsequent ED TPDU sent on the same
transport connection, the transport entity shall allocate a
...
... transport protocol class to be operated over
the requested transport connection. This
field shall take one of the following values:
...
... Bits 4-1 of octet 7 define options to be used on the requested
transport connection as follows:
...
... octets including the header) to be used over the requested
transport connection. The coding of this parameter is:
Parameter code: 1100 0000
...
...
c) DST-REF: Reference identifying the requested transport
connection at the remote transport entity;
...
... entity;
d) SRC-REF: Reference identifying the requested transport
connection at the remote transport entity.
...
... class and option to be operated over the accepted
transport connection according to the negotiation rules
specified in 6.5;
...
...
d) REASON: Defines the reason for disconnecting the
transport connection. This field shall take one of the
following values:
...
...
NOTE - The length of this field is limited to the negotiated TPDU
size for this transport connection minus 3 octets in Classes 0
and 1, and minus 5 octets (normal header format ...
... tables. The state tables show the state of a transport
connection, the events that occur in the protocol, the actions
taken and the resultant state.
...