Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1999-01-27
2001-10-30
Olms, Douglas (Department: 2732)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S428000
Reexamination Certificate
active
06310882
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to a switching device for very high data rates, and more specifically to a fiber optic media module in a computer network concentrator.
BACKGROUND OF THE INVENTION
A network concentrator contains a plurality of modules connecting together a plurality of stations. These modules can be roughly divided into management modules and communication or media modules. The media modules connect to links which in turn connect to individual stations or to other concentrators. The management modules control the operation of the media modules and the interaction between the communication modules.
A media modules perform the actual transferring of data in a computer network. Data received on one link of a concentrator can be sent out on another link of a concentrator in order to transfer data between two stations in a computer network. A network concentrator can have a plurality of media modules, and each media module can have one or more ports for connecting to one or more links. Data can enter into a media module on one port, and then be sent out on another port of the same media module, or the media module can send that data to the backplane of a concentrator where the data is sent to another media module, and then the data is sent out on a port of the another media module. The media modules have a switch engine which analyzes incoming data and determines if the data should be sent out on one of the other ports of a media module, or be placed onto the backplane of the concentrator. The switch engine of a media module also listens to the backplane, and determines if any of the data on the backplane should be received and forwarded to one of the ports of the respective media module.
As the number of stations connected together in a computer network grows, as computer applications grow to transfer larger and larger amounts of data, such as audio and video, and as computer networks spread physically further apart, there is a great need for a single link to transfer data at very high rates.
The present invention anticipates that hundreds, maybe thousands of users at one location will want to exchange data, especially audio and video data with hundreds or possibly thousands of users at another location spaced relatively far from the first location. The high data rates needed to timely transfer the information from one location to another will require fast processing of the data at each location to deliver the data to its proper station. The high data rate possible over links between two locations is often much higher than economically possible data processing rates at each end of the link.
SUMMARY AND OBJECTS OF THE INVENTION
It is the primary object of the present invention to provide data processing at the end of a link which is comparable to the high data rates available in a fiber optic link and the backplane of a concentrator, while still being economical relative to the backplane and the fiber optic link.
The present invention accomplishes this object by a switching architecture which is placed between a port connecting to a fiber optic gigabit ethernet link and a 2 Gbit/sec backplane of a concentrator. A port means connects to the link for both receiving and transmitting data packets from and to the link. The port means has a concentrator side input for receiving data packets to be transmitted onto the link. The port means also has a concentrator side output for delivering data packets received from the link. A first forwarding and translating engine (FTE) has an input and an output. The input of the first FTE is connected to the concentrator side output of the port means. The first FTE receives a data packet from the port means, and analyzes the data packet to determine if the data packet should be forwarded to the backplane of the concentrator. The first FTE ignores the data packet if the data packet is not to be forwarded. If the data packet is to be forwarded, the first FTE sends the data packet out onto the output of the first FTE, and performs any modifications or translation of the data packet according to the protocol of the backplane. The first FTE includes an address forwarding database for indicating what type of data packets are to be forwarded, and how they are to be translated or modified. In particular, the first FTE reads the destination address of a packet and consults the address forwarding database means to determine if that destination address can be reached through the backplane. If the address database means determines that the destination address can be reached through the backplane, the FTE forwards the data packet through the backplane. The first FTE, also analyzes the source address of a packet received from the port, to determine which addresses can be reached through the port. The output of the first FTE is sent to a backplane connection means for connecting to the backplane of the network concentrator, and for both receiving and transmitting data packets from and to the backplane. The backplane connection means has a port side input connected to the output of the first FTE, and for receiving data packets to be transmitted onto the backplane. The backplane connection means also has a port side output means for delivering data packets received from the backplane.
A second FTE has an input and an output. The input of a second FTE is connected to the port side output of the backplane connection means. The second FTE receives a data packet from the backplane connection means, and analyzes the data packet in a manner similar to the first FTE to determine if a packet should be forwarded to the port. The process of the second FTE with regard to the data packets is substantially similar to the process of the first FTE, except that it is determined whether or not the data packets from the backplane should be forwarded to the port.
This switch architecture therefore uses separate transmit and receive channels with independent forwarding tables. The first and second FTE's can be substantially identical, and are preferably switch engine ASIC's (Application Specific Integrated Circuit). Each switch engine ASIC has an associated memory for packet memory and look-up memory. The memories associated with each ASIC are each independent and are able to store forwarding information for addresses independently, or they can be programmed with the same address forwarding database. This architecture produces the bandwidth between the switching ASIC's, and the two associated memories by half of the total system requirement. This architecture is optimized for a single port gigabit ethernet switch in a multifunction hub. The switching ASIC devices are preferably identical and are devices where each device would be used alone in a switch architecture for a lower speed, such as 10Mbit ethernet applications. This provides a switch architecture for gigabit applications, where a switch engine does not need to be especially designed for the new high data rate, but two lower speed switch engines are combined to handle the new high data rate.
The port means preferably includes means for transmitting and receiving data packets to and from the link at substantially 1,000 Mb/s and the first and second FTE operate at substantially 25 MHZ. The backplane connection means transmits and receives data packets to and from the backplane of the concentrator at 2 Gbit/sec, and the port input and output of the backplane connection means provides 32 bit full duplex 25 MHz interfaces and transfers the data packets at 800 Mbit/sec to the first and second FTE means.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.
REFERENCES:
patent: 5311593 (1994-05-01), Carmi
patent: 5319644
Kapoor Harsh
Lorenz Gary D.
Myrick Brian J.
Thompson Bruce W.
Weaver Charles R.
3Com Corporation
McGlew and Tuttle , P.C.
Olms Douglas
Vanderpuye Ken
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