Ethernet extender
First Claim
1. An apparatus for interfacing between an Ethernet local area network and a metropolitan area data communication network comprising:
- a circuit means forming a local area network node for connecting to an Ethernet local area network via an Ethernet medium;
a bridge subsystem coupled to said connection means which is operative to accept Ethernet packets and to control access to the metropolitan area data communication network, said bridge subsystem including;
a modem subsystem coupled to a wide area network medium of the metropolitan area data communication network for communicating Ethernet-type packets over a frequency channel of the metropolitan area data communication network, said frequency channel employing timed frames during which each one of said Ethernet-type packets is conveyed, link control means for allocating time in each one of said time frames into at least a first (reservation) segment and a second (payload) segment, said second segment being of sufficient capacity to contain an unmodified one of said Ethernet-type packets, and said first segment being for arbitrating among bridge subsystems requesting access to said frequency channel;
means for buffering said Ethernet-type packets; and
control means for arbitrating access to said wide area network medium, wherein said control means is operative to subdivide said first segment into a plurality of subsegments, each said subsegment being employed to arbitrate for access to the second segment of a future timed frame.
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Accused Products
Abstract
A telecommunication bridge system uses synchronized arbitration in a portion of a frame of a Radio Frequency (RF) subsystem and is transparent to Ethernet layer protocols and Ethernet-type packets in order to increase bandwidth utilization and effectively extend Ethernet networks to metropolitan-area-wide application. The telecommunication bridge system comprises an enhanced Ethernet network interface subsystem coupled to a conventional Ethernet medium and a control subsystem including an RF modem, in turn coupled to a frame synchronized RF medium in a metropolitan-sized network. On one side the control subsystem emulates all Ethernet layer protocols and on the other side conducts a prioritized arbitration scheme during only a portion of a time division multiplexed frame, the remainder of the frame for carrying a payload of unmodified packets to other bridges. Included in the controller subsystem is a two-way Manchester/NRZ Code converter, its own intelligence and packet buffering using a microprocessor and random access memory.
60 Citations
2 Claims
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1. An apparatus for interfacing between an Ethernet local area network and a metropolitan area data communication network comprising:
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a circuit means forming a local area network node for connecting to an Ethernet local area network via an Ethernet medium; a bridge subsystem coupled to said connection means which is operative to accept Ethernet packets and to control access to the metropolitan area data communication network, said bridge subsystem including; a modem subsystem coupled to a wide area network medium of the metropolitan area data communication network for communicating Ethernet-type packets over a frequency channel of the metropolitan area data communication network, said frequency channel employing timed frames during which each one of said Ethernet-type packets is conveyed, link control means for allocating time in each one of said time frames into at least a first (reservation) segment and a second (payload) segment, said second segment being of sufficient capacity to contain an unmodified one of said Ethernet-type packets, and said first segment being for arbitrating among bridge subsystems requesting access to said frequency channel; means for buffering said Ethernet-type packets; and control means for arbitrating access to said wide area network medium, wherein said control means is operative to subdivide said first segment into a plurality of subsegments, each said subsegment being employed to arbitrate for access to the second segment of a future timed frame.
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2. A method for arbitrating among bridges requesting access to time frames in a metropolitan area digital data communication system comprising the steps of:
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establishing a first (reservation) time segment and a second (payload) time segment of a frame for communication of digital packets; establishing within said first time segment a plurality of reservation subsegments; at each said bridge first transmitting a reservation packet the reservation subsegment corresponding with a position in a queue and observing for a collision; thereafter and during each successive frame if no collision has occurred, at each such bridge, transmitting the reservation packet, with identification of the reservation subsegment, in the reservation subsegment corresponding with said position in a queue; and upon clearing of each said reservation packet from said position in the queue and during each successive frame, at each bridge, transmitting said reservation packet in the reservation subsegment corresponding with said position in the queue.
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Specification