Process and devices for establishing point-to-multipoint...

Details Process and devices for establishing point-to-multipoint... Process and devices for establishing point-to-multipoint...

1998-09-15

2002-07-09

Olms, Douglas (Department: 2732)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

C370S388000

Reexamination Certificate

active

06418142

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a process for establishing point-to-multipoint connections and multipoint-to-point connections in a coupling field, comprised of a number of stages, each with a number of switching modules, each of which has a number of inputs and outputs that can be freely connected to one another. It is also directed to a related a coupling field, control device, and switching center.
BACKGROUND OF THE INVENTION
The splitting of an incoming connecting line in a coupling field into a number of continuing connecting lines and the coupling together of a number of incoming connecting lines in another coupling field into a common, continuing connecting line are known in the field of SDH technology (synchronous digital hierarchy) from the ITU-T Recommendation G.841 (DRAFT) “Types and Characteristics of SDH Network Protection Architectures”, April 1995 version, FIGS. 5-7 (p. 51). In the coupling fields represented there, each coupling field input is connected to a number of coupling field outputs by means of a point-to-multipoint connection and a number of coupling field inputs are connected to one coupling field output by means of a multipoint-to-point connection. The represented use of at least two different and independent, i.e. redundant, connecting paths increases the transmission reliability in telecommunication networks or parts of them. A first pair that is comprised of a data source and a data sink indicated by arrows are connected by way of a first coupling field (“matrix connection”), two redundant transmission path pairs, and a second coupling field (“matrix connection”) to a second pair comprised of a data source and a data sink. The coupling fields mentioned are parts of SDH network nodes, so-called “cross-connects”. The disposition of the transmission paths in pairs here is necessary for a transmission in full-duplex mode. For a transmission in half-duplex mode or for a unidirectional transmission, only one channel of each of the transmission path pairs would be required. The transmission path pair that is active for data transmission is called the SNCw connection (subnetwork connection working), the redundant transmission path pair is called SNCP connection (subnetwork connection protection). The transmission in one direction on each channel of the doubled transmission path pair will be represented below. In the opposite direction, the transmission is accordingly executed in reverse.
A data stream to be transmitted from the first data source to the second data sink is duplicated by the first coupling field and the data stream and its duplicate are transmitted to the data sink in parallel fashion, each on a channel of the redundant transmission paths SNCp and SNCw. Immediately upstream of the data sink, the data stream and its duplicate are received by the second coupling field on the redundant transmission paths and are coupled together. In so doing, the data stream and its duplicate are tested as to their quality so that as a result, if possible, a perfectly received data stream can be selected and conveyed to the data sink. If both of the redundant transmission paths do not fail or suffer interference simultaneously, then the data stream can be transmitted from the data source to the data sink in the above-described manner with a high degree of transmission quality and transmission reliability.
In conjunction with
FIG. 1
, first a situation is described that can result without the use of the process according to the invention.
FIG. 1
shows a coupling field in three stages, each comprised of five switching modules, with currently used connections between the switching modules of the three stages. The coupling field is comprised of an input stage (I) with five switching modules
11
,
12
,
13
,
14
, and
15
, an intermediary stage (II) with five switching modules
21
,
22
,
23
,
24
, and
25
, and an output stage (III) with five switching modules
31
,
32
,
33
,
34
, and
35
. Each of the respective five switching modules of the input stage (I) and the output stage (III) is connected to each of the five switching modules of the intermediary stage (II) via intermediary lines not shown in the FIG. However, connections that extend by way of these intermediary lines are in fact represented, so that a few intermediary lines can therefore be discerned indirectly. The intermediary lines are thus disposed between the input stage (I) and the intermediary stage (II) and between the intermediary stage (II) and the output stage (III). There is always an intermediary line between each output of a switching module of one stage and each input of a switching module of a neighboring stage. An intermediary line of this kind is used in
FIG. 1
, e.g. between the switching modules
11
and
21
.
In the example represented, the switching modules each have five inputs and five outputs. One input of a switching module can be selectively connected inside the switching module to at least one output of the same switching module. An output of a switching module can likewise be selectively connected to at least one input of the same switching module. A switching module can simultaneously connect up to five independent connections between each of its inputs and each of its outputs. The switching modules
11
and
31
have this kind of a switching state. In these switching modules, like in most of the others of the coupling field, a direct switching through of the inputs and outputs is represented by horizontal lines between the inputs and the outputs. This is only intended to serve as a simple depiction.
If a connection through the coupling field of only one input of only one switching module of the input stage (I) leads to only one output of only one switching module of the output stage (III), then this reversible, definite connection is also called a “unicast connection”. The “unicast connections” connected in
FIG. 1
are represented by thin solid lines.
However, the connections described at the beginning are also possible, in which the data that are received by the coupling field on one of its inputs are duplicated and sent in parallel fashion on a number of its outputs. Here, constellations of this kind are called point-to-multipoint connections or “multicast connections”. “Multicast connections” are depicted in the FIGs. with thick, dashed lines. A “multicast connection” of this kind is connected, for example, in the switching module
24
and on the input end, leads to the switching module
11
and on the output end, leads to the switching modules
31
and
32
. Another “multicast connection” leads from the input A
14
of the switching module
14
, by way of the switching module
24
to the output A
33
of the switching module
33
and to the output A
34
of the switching module
34
.
In a similar manner, a number of inputs of a coupling field can also be coupled together with a single one of its outputs into a connection that is called a multipoint-to-point connection here or is also called a “merge connection”. “Merge connections” are represented in the FIGs. with thick, solid lines. The switching module
25
couples one such “merge connection” together between its inputs toward the switching modules
11
and
12
and its output toward the switching module
31
. Another “merge connection” is produced between the inputs B
14
and B
15
of the switching modules
14
and
15
by way of the switching module
25
to the output B
35
of the switching module
35
. In a “merge connection”, the data stream and its duplicate, which have been received in parallel on the input end by the coupling field, are tested as to their quality by the coupling switching module. If the data stream or its duplicate have been identified as error-free, then a single error-free data stream is selected and conveyed further to a single output. If neither the data stream nor the duplicate are error-free, then an error-encumbered data stream, possibly additionally marked especially because it contains errors, could also be supplied to the output.
Duplicated data streams are

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