Memory organization in a switching device
First Claim
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1. A router for switching a data packet from a source to a destination in a network, the router comprising:
- an input port for receiving the data packet, the data packet formatted in accordance with a first protocol;
a divider for dividing the data packet into uniform length cells for temporary storage in the router, the divider dividing the data packet without changing the formatting of the data packet;
a distributed memory comprising a plurality of physically separated memory banks, each memory bank including a global data area for storing a portion of the data packet;
an input switch for streaming across the memory banks uniform portions of the data packet such that consecutive cells associated with the data packet are stored in consecutive banks of the distributed memory;
a controller for determining packet routing through the router;
an output switch for extracting in order the portions of the data packet stored in the global data area of each memory bank including reassembling the cells in proper order to reconstruct the data packet formatted in accordance with the first protocol and forwarding the data packet to an appropriate output port; and
an output port for transferring the data packet to the destination.
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Abstract
A router for switching data packets from a source to a destination in a network in which the router includes a distributed memory. The distributed memory includes two or more memory banks. Each memory bank is used for storing uniform portions of a data packet received from a source and linking information for each data packet to allow for the extraction of the uniform portions of a data packet from distributed locations in memory in proper order after a routing determination has been made by the router.
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Citations
18 Claims
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1. A router for switching a data packet from a source to a destination in a network, the router comprising:
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an input port for receiving the data packet, the data packet formatted in accordance with a first protocol;
a divider for dividing the data packet into uniform length cells for temporary storage in the router, the divider dividing the data packet without changing the formatting of the data packet;
a distributed memory comprising a plurality of physically separated memory banks, each memory bank including a global data area for storing a portion of the data packet;
an input switch for streaming across the memory banks uniform portions of the data packet such that consecutive cells associated with the data packet are stored in consecutive banks of the distributed memory;
a controller for determining packet routing through the router;
an output switch for extracting in order the portions of the data packet stored in the global data area of each memory bank including reassembling the cells in proper order to reconstruct the data packet formatted in accordance with the first protocol and forwarding the data packet to an appropriate output port; and
an output port for transferring the data packet to the destination.
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2. An apparatus for use in a router, the router for switching data packets from a source to a destination in a network, the router including one or more input ports for receiving data packets, a divider for dividing the data packets into uniform portions without changing the format of the data packet and one or more output ports operable to forward the data packets to other devices on the network based on routing decisions made by the router, the apparatus comprising:
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a distributed memory comprising a plurality of physically separated memory banks;
a switch coupled to the divider operable to stream the uniform portions to the memory banks where consecutive cells associated with a data packet are stored in consecutive memory banks;
each memory bank operable to store uniform portions of a data packet received from the source and linking information to allow for the extraction of the uniform portions of the data packet from the plurality of memory banks in proper order after a routing determination has been made by the rout4er such that the data packet as originally formatted can be routed to another device in the network. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of routing a data packet through a router in a system transmitting data packets between a source and a destination over a network including the router, the method comprising:
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receiving the data packet;
dividing the data packet into cells of a fixed size;
storing the cells in a distributed memory, the distributed memory including two or more memory banks where consecutive cells from the data packet are stored in consecutive banks of the distributed memory; and
storing linking information in one bank of the memory for linking cells of the data packet that are stored throughout the distributed memory, the linking information used for extracting the cells in order for transmission from the router to the destination.
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15. A method of storing a data packet in a router while a look-up engine determines a proper path through the router for the data packet in a system transmitting data packets between a source and a destination over a network including the router, the method comprising:
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dividing the data packet into fixed length cells without changing the formatting of the data packet;
storing the cells and linking information for reconstructing the data packet across a global data buffer, the global data buffer including two or more memory banks where the data packet is divided among the memory banks including storing consecutive cells associated with a data packet in consecutive memory banks of the global data buffer; and
a switch for gathering cells associated with the data packet from the global data buffer and reconstructing the data packet prior to forwarding the packet to the destination.
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16. A method for determining which data packets stored in a router are to be passed through the router in a system transmitting data packets between a source and a destination over a network including the router, the method comprising:
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determining a route through the router for a data packet, the route including a notification indicating a starting address in memory where the data packet is stored;
processing the notification including queuing the notification with other notifications to be output on the same output port of the router in a stream queue;
determining the fullness of the stream queue;
determining a drop criterion based in part on fullness of the stream queue;
generating a random number;
comparing the random number and the drop criterion and dropping the notification based upon results of the comparison. - View Dependent Claims (17, 18)
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Specification