Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1999-03-11
2003-05-06
Chin, Wellington (Department: 2664)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S466000
Reexamination Certificate
active
06560233
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a data processing unit used as a constitutional element of a network relaying apparatus, such as router and bridge, and a network relaying apparatus applying the data processing unit.
2. Description of Related Art
A data processing unit used as a constitutional element of a network relaying apparatus such as a router and a bridge generally includes a memory for storing received packets or packets to be transmitted, a memory controller for controlling reading from and writing into the memory and for controlling transfer of packets to and from another data processing unit connected to another network, a network controller for transferring packets received from a network to the memory via the memory controller and for sending packets, that were retrieved from the memory via the memory controller, to the network, and a processor for retrieving a header portion of a packet, analyzing it and, depending on the result of the analysis, issuing a request to the memory controller or the network controller to retrieve the packet from the memory and transfer it to another data processing unit or network.
In such a data processing unit, various processing, including the processing to transfer a packet between the network controller and the memory, the processing for the processor to read a packet header portion from the memory, and the processing to read a packet from the memory for transfer to another data processing unit, occur independently of each other. This gives rise to a problem of conflict among memory accesses made by these processing, which constitutes the most serious factor that hampers an increased speed. To alleviate the access contention, it is common practice to use a high-speed memory device or a special memory device (dual port memory) that allows independent parallel accesses by the processor and the network controller.
SUMMARY OF THE INVENTION
With data transmission speeds of networks increasing in recent years, a data processing unit used in a network relaying apparatus such as a router and a bridge is required to increase the speed of processing, including the processing of a network controller for reading the sending packets from memory and writing the received packets into memory. It is also necessary to avoid performance degradation caused by memory access conflicts between a network controller and a processor. To this end, the data processing unit in a conventional network relaying apparatus is required to limit the number of network controllers that can be mounted in the apparatus. Alternatively, it is necessary to use a high-speed memory device or a dual port memory device that allows independent accesses from the processor and the network controller. There are problems with these countermeasures, however. The former limits the number of networks that can be connected to the network relaying apparatus while the latter raises cost as it requires an expensive memory.
An object of the present invention is to provide a data processing unit that improves the packet processing capability by minimizing a conflict of accesses to memory where packets are stored, without limiting the number of network controllers that can be mounted in the apparatus, and also to provide a network relaying apparatus that uses such a data processing unit as its constitutional element.
Another object of the present invention is to provide a data processing unit that improves the packet processing capability by minimizing a conflict of accesses to memory where packets are stored, without using an unnecessarily high-speed memory device or a dual port memory device, and also to provide a network relaying apparatus that uses such a data processing unit as its constitutional element.
To achieve the above objectives, this invention provides, in addition to a memory (first memory) in which to store packets received from a network or packets transferred from another data processing unit, a memory (second memory) that can be accessed independently of the first memory and in which a header portion of a packet is stored (or copied) at the same time that the packet is stored in the first memory. The processor stores the header portion of a packet into the second memory and references the header portion stored in the second memory to analyze the packet header portion. The network controller writes and reads packets into and from the first memory independently of the processor that performs the header analyzing processing.
As a result, the header analyzing processing on a packet and the transfer processing on another packet can be performed parallelly. This prevents a system performance degradation that would otherwise be caused by a conflict of accesses to a packet storing memory. This in turn alleviates the limitations imposed by the performance degradation on the number of network controllers that can be used in the system. It is therefore possible to use a memory device with a somewhat slow cycle time or a single port.
REFERENCES:
patent: 5465331 (1995-11-01), Yang et al.
patent: 5640599 (1997-06-01), Roskowski et al.
patent: 5938736 (1999-08-01), Muller et al.
patent: 5978951 (1999-11-01), Lawler et al.
patent: 6032190 (2000-02-01), Bremer et al.
patent: 6160809 (2000-12-01), Adiletta et al.
patent: 6172990 (2001-01-01), Deb et al.
Hatanaka Satoshi
Matsuyama Nobuhito
Sugai Kazuo
Yamakawa Yukisada
Chin Wellington
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
Schultz William
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