Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-01-05
2003-07-15
Marcelo, Melvin (Department: 2663)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S412000
Reexamination Certificate
active
06594263
ABSTRACT:
TECHNICAL FIELD
The present invention relates to methods and devices for handling transmission of data cells from a node, where the cells belong to different channels and are transmitted from a station in predetermined rates specific for each channel.
BACKGROUND
In the transmission of calls or messages in an asynchronous network each call or message is divided in short cells or segments which are forwarded in the network, each cell then belonging to a specific call or message or generally to a particular logical connection. These connections are established when the call is made or the request is made for transmitting a message, e.g. a digital file, through the network. Depending on the user or requester of the transmission, each logical connection is assigned a predetermined transmission rate which is a fraction of the total transmission rate of cells for the nodes in the network, the magnitude of the fraction implying different costs for the user or requester. There is then a problem of issuing the data cells in these rates from a station into the network so that these predetermined rates are not exceeded. The same problem can also exist in nodes inside the network, where the transmission rates of the different logical connections can have been unbalanced by the fact that the cells can pass through different paths, that buffers may be full and some cells are then discarded, etc.
In the published patent European application EP-A1 0 609 114 a method is disclosed for transmission of cells in an ATM-network. The method comprises a number of steps including that in one of the steps the cells are separated by a least time interval representing a known time resolution. In another step the cells are separated by a least time interval representing the maximum allowed transmission rates for the respective user. The time separation is performed by means of different timers. For each separation of the first kind the cells are collected in a number of files of cells or lists of cells, which are transmitted successively. In the other separation, the cells having different allowed maximum transmission rates are distributed over the files or lists, for each transmission rate evenly or with an equal spacing over files or lists.
In the published International patent application WO-A1 94/14266 a system is disclosed for controlling the flow of cells through nodes in an ATM-network. The switches of the system which are equipped with both input and output buffers can, by means of throttling, control the flow of cells from the input buffers if an addressed output buffer is overloaded. In an embodiment each output buffer has a device detecting its fill level, the detected value being reported continuously for controlling the throttling. The purpose of the throttling is here primarily only for preventing overload or overflow of the output buffers.
Other systems using throttling in networks are disclosed in U.S. Pat. No. 5,280,470 and the published European patent application EP-A2 0 573 739.
SUMMARY
It is an object of the invention to provide methods and devices for handling transmission, from a considered point such as a station or node, of cells which belong to different logical connections, where all cells are transmitted at predetermined rates, the handling method and device requiring only simple hardware with an efficient use of memory areas.
In particular, it is an object of the invention to provide methods and devices for handling transmission of cells from a station or node, where predetermined rates, established for cells belonging to different logical connections, are not exceeded and cells are transmitted simultaneously from the station at the highest possible total rate.
In particular, it is a further object of the invention to provide methods and devices for handling transmission of cells from a station or node, where in the transmission of cells, in the case where the sum of predetermined rates, established for cells belonging to different logical connections, exceeds the total transmission rate of the station or node, or worded equivalently, exceeds the total transmission band width, all predetermined rates are decreased in a fair manner so that no connection will be more favoured than others, e.g. that no connection is blocked when the others are not, and in particular that all connections having the same predetermined rate are handled equally, none of them being given more transmission time than the others.
In particular, it is a still further object of the invention to provide methods and devices for handling transmission of cells from a point or station, where cells belonging to different logical connections or from different sources arrive to the station at different rates and at some time periods even no cells will arrive belonging to some connections, the transmission capacity is assigned to the connections based on their instantaneous needs, so that during those time periods, when there are cells ready to be transmitted a connection is given its share of the total transmission bandwidth, based on the predetermined rate of the connection, and in other cases when there are no cells, this bandwidth is used for transmitting cells from other connections, where the transmission from the connection is started rapidly thereafter when it has cells which are ready to be transmitted.
It is another object of the invention to provide methods and devices for transmission of cells from a station or node, where the transmission rates for cells belonging to different logical connections can be set with a high resolution and for every connection independent of all other connections.
It is a further object of the invention to provide methods and devices for transmission of cells from a station or node, where the transmission rate for cells belonging to a logical connection can be changed during the transmission of the cells.
It is a still further object of the invention to provide methods and devices for transmission of cells from a station or node, where the total handling time for handling the transmission of cells belonging to different logical connections will principally not increase, when the number of established logical connections increases, and where the amount of additional hardware required for the method and in the device is only moderate in the case, where the method and device are extended to handling more logical connections than before.
It is another object of the invention to provide methods and devices for handling transmission, from a station or node, of cells which belong to different logical connections, for which method and device all cells belonging to each connection are transmitted at a rate predetermined for each connection, the handling method and device giving a smooth cell flow out from the station or node.
Thus in a station or terminal for a network data cells are transmitted from the terminal and the cells are arranged to belong to different logical connections, which are derived from various logical or physical sources. Each source and thus connection is supposed to require a particular transmission rate, which is not to be exceeded and which can be changed. Then for each one of a number of successive time slots a queue is arranged, the first or current queue being the one which is pointed to by a pointer. The time slot queues comprise in a consecutive order, identifiers of those connections for which a data cell is to be transmitted, or they may in some special cases even contain the cells themselves. The first position in such a queue indicates the connection, for which a data cell is to be sent with the highest degree of priority. The following positions indicate connections which have lower degrees of priority in a decreasing order. The first or next data cell of the logical connection the identifier of which is the first one in the time slot queue as pointed to by the pointer is then transmitted from the station and an identifier of the same connection is added to that other queue which has a distance from the considered queue in the sequential order of que
Kwoh Jasper
Marcelo Melvin
Telefonaktiebolaget LM Ericsson (publ)
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